[66d68c] | 1 | ///////////////////////////////////////////////////////////////////////////// |
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[341696] | 2 | version="$Id$"; |
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[4c4e0d] | 3 | category="Algebraic Geometry"; |
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[2e6eac2] | 4 | info=" |
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[471d0cf] | 5 | LIBRARY: reszeta.lib topological Zeta-function and |
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| 6 | some other applications of desingularization |
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[2e6eac2] | 7 | |
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| 8 | AUTHORS: A. Fruehbis-Krueger, anne@mathematik.uni-kl.de, |
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| 9 | @* G. Pfister, pfister@mathematik.uni-kl.de |
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| 10 | |
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[4c4e0d] | 11 | REFERENCES: |
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[66d68c] | 12 | [1] Fruehbis-Krueger,A., Pfister,G.: Some Applications of Resolution of |
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| 13 | @* Singularities from a Practical Point of View, in Computational |
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[4c4e0d] | 14 | @* Commutative and Non-commutative Algebraic Geometry, |
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| 15 | @* NATO Science Series III, Computer and Systems Sciences 196, 104-117 (2005) |
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[66d68c] | 16 | [2] Fruehbis-Krueger: An Application of Resolution of Singularities: |
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| 17 | @* Computing the topological Zeta-function of isolated surface singularities |
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[4c4e0d] | 18 | @* in (C^3,0), in D.Cheniot, N.Dutertre et al.(Editors): Singularity Theory, @* World Scientific Publishing (2007) |
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| 19 | |
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[f27ab81] | 20 | PROCEDURES: |
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[2e6eac2] | 21 | intersectionDiv(L) computes intersection form and genera of exceptional |
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| 22 | divisors (isolated singularities of surfaces) |
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| 23 | spectralNeg(L) computes negative spectral numbers |
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| 24 | (isolated hypersurface singularity) |
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[f4c2ba] | 25 | discrepancy(L) computes discrepancy of given resolution |
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| 26 | zetaDL(L,d) computes Denef-Loeser zeta function |
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[2e6eac2] | 27 | (hypersurface singularity of dimension 2) |
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| 28 | collectDiv(L[,iv]) identify exceptional divisors in different charts |
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| 29 | (embedded and non-embedded case) |
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| 30 | prepEmbDiv(L[,b]) prepare list of divisors (including components |
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| 31 | of strict transform, embedded case) |
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| 32 | abstractR(L) pass from embedded to non-embedded resolution |
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[1e1ec4] | 33 | computeV(re,DL) multiplicities of divisors in pullback of volume form |
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| 34 | computeN(re,DL) multiplicities of divisors in total transform of resolution |
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[2e6eac2] | 35 | "; |
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[4cfbb0] | 36 | LIB "resolve.lib"; |
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[2e6eac2] | 37 | LIB "solve.lib"; |
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| 38 | LIB "normal.lib"; |
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| 39 | /////////////////////////////////////////////////////////////////////////////// |
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[f27ab81] | 40 | static proc spectral1(poly h,list re, list DL,intvec v, intvec n) |
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[2e6eac2] | 41 | "Internal procedure - no help and no example available |
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| 42 | " |
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| 43 | { |
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| 44 | //--- compute one spectral number |
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| 45 | //--- DL is output of prepEmbDiv |
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| 46 | int i; |
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| 47 | intvec w=computeH(h,re,DL); |
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| 48 | number gw=number(w[1]+v[1])/number(n[1]); |
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| 49 | for(i=2;i<=size(v);i++) |
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| 50 | { |
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| 51 | if(gw>number(w[i]+v[i])/number(n[i])) |
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| 52 | { |
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| 53 | gw=number(w[i]+v[i])/number(n[i]); |
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| 54 | } |
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| 55 | } |
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| 56 | return(gw-1); |
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| 57 | } |
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| 58 | |
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| 59 | /////////////////////////////////////////////////////////////////////////////// |
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| 60 | |
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| 61 | proc spectralNeg(list re,list #) |
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| 62 | "USAGE: spectralNeg(L); |
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| 63 | @* L = list of rings |
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| 64 | ASSUME: L is output of resolution of singularities |
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| 65 | RETURN: list of numbers, each a spectral number in (-1,0] |
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| 66 | EXAMPLE: example spectralNeg; shows an example |
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| 67 | " |
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| 68 | { |
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| 69 | //----------------------------------------------------------------------------- |
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| 70 | // Initialization and Sanity Checks |
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| 71 | //----------------------------------------------------------------------------- |
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| 72 | int i,j,l; |
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| 73 | number bound; |
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| 74 | list resu; |
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| 75 | if(size(#)>0) |
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| 76 | { |
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| 77 | //--- undocumented feature: |
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| 78 | //--- if # is not empty it computes numbers up to this bound, |
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| 79 | //--- not necessarily spectral numbers |
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| 80 | bound=number(#[1]); |
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| 81 | } |
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| 82 | //--- get list of embedded divisors |
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| 83 | list DL=prepEmbDiv(re,1); |
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| 84 | int k=1; |
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| 85 | ideal I,delI; |
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| 86 | number g; |
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| 87 | int m=nvars(basering); |
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| 88 | //--- prepare the multiplicities of exceptional divisors N and nu |
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| 89 | intvec v=computeV(re,DL); // nu |
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| 90 | intvec n=computeN(re,DL); // N |
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| 91 | //--------------------------------------------------------------------------- |
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| 92 | // start computation, first case separately, then loop |
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| 93 | //--------------------------------------------------------------------------- |
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| 94 | resu[1]=spectral1(1,re,DL,v,n); // first number, corresponding to |
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| 95 | // volume form itself |
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| 96 | if(resu[1]>=bound) |
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| 97 | { |
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| 98 | //--- exceeds bound ==> not a spectral number |
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| 99 | resu=delete(resu,1); |
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| 100 | return(resu); |
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| 101 | } |
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| 102 | delI=std(ideal(0)); |
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| 103 | while(k) |
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| 104 | { |
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| 105 | //--- now run through all monomial x volume form, degree by degree |
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| 106 | j++; |
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| 107 | k=0; |
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| 108 | I=maxideal(j); |
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| 109 | I=reduce(I,delI); |
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| 110 | for(i=1;i<=size(I);i++) |
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| 111 | { |
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| 112 | //--- all monomials in degree j |
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| 113 | g=spectral1(I[i],re,DL,v,n); |
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| 114 | if(g<bound) |
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| 115 | { |
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| 116 | //--- otherwise g exceeds bound ==> not a spectral number |
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| 117 | k=1; |
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| 118 | l=1; |
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| 119 | while(resu[l]<g) |
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| 120 | { |
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| 121 | l++; |
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| 122 | if(l==size(resu)+1){break;} |
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| 123 | } |
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| 124 | if(l==size(resu)+1){resu[size(resu)+1]=g;} |
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| 125 | if(resu[l]!=g){resu=insert(resu,g,l-1);} |
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| 126 | } |
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| 127 | else |
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| 128 | { |
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| 129 | delI[size(delI)+1]=I[i]; |
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| 130 | } |
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| 131 | } |
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| 132 | attrib(delI,"isSB",1); |
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| 133 | } |
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| 134 | return(resu); |
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| 135 | } |
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| 136 | example |
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| 137 | {"EXAMPLE:"; |
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| 138 | echo = 2; |
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| 139 | ring R=0,(x,y,z),dp; |
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| 140 | ideal I=x3+y4+z5; |
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| 141 | list L=resolve(I,"K"); |
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| 142 | spectralNeg(L); |
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[bdc6cb] | 143 | LIB"gmssing.lib"; |
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[2e6eac2] | 144 | ring r=0,(x,y,z),ds; |
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| 145 | poly f=x3+y4+z5; |
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| 146 | spectrum(f); |
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| 147 | } |
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| 148 | |
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| 149 | /////////////////////////////////////////////////////////////////////////////// |
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[f27ab81] | 150 | static proc ordE(ideal J,ideal E,ideal W) |
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[2e6eac2] | 151 | "Internal procedure - no help and no example available |
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| 152 | " |
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| 153 | { |
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| 154 | //--- compute multiplicity of E in J -- embedded in W |
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| 155 | int s; |
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| 156 | if(size(J)==0){~;ERROR("ordE: J=0");} |
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| 157 | ideal Estd=std(E+W); |
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| 158 | ideal Epow=1; |
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| 159 | ideal Jquot=1; |
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| 160 | while(size(reduce(Jquot,Estd))!=0) |
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| 161 | { |
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| 162 | s++; |
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| 163 | Epow=Epow*E; |
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| 164 | Jquot=quotient(Epow+W,J); |
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| 165 | } |
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| 166 | return(s-1); |
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| 167 | } |
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| 168 | |
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| 169 | /////////////////////////////////////////////////////////////////////////////// |
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[1e1ec4] | 170 | proc computeV(list re, list DL) |
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| 171 | "USAGE: computeV(L,DL); |
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| 172 | L = list of rings |
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| 173 | DL = divisor list |
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| 174 | ASSUME: L has structure of output of resolve |
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| 175 | DL has structure of output of prepEmbDiv |
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| 176 | RETURN: intvec, |
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| 177 | i-th entry is multiplicity of i-th divisor in |
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| 178 | pullback of volume form |
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| 179 | EXAMPLE: example computeV; shows an example |
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[2e6eac2] | 180 | " |
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| 181 | { |
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| 182 | //--- computes for every divisor E_i its multiplicity + 1 in pi^*(w) |
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| 183 | //--- w a non-vanishing 1-form |
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| 184 | //--- note: DL is output of prepEmbDiv |
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| 185 | |
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| 186 | //----------------------------------------------------------------------------- |
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| 187 | // Initialization |
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| 188 | //----------------------------------------------------------------------------- |
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| 189 | def R=basering; |
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| 190 | int i,j,k,n; |
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| 191 | intvec v,w; |
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| 192 | list iden=DL; |
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| 193 | v[size(iden)]=0; |
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| 194 | |
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| 195 | //---------------------------------------------------------------------------- |
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| 196 | // Run through all exceptional divisors |
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| 197 | //---------------------------------------------------------------------------- |
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| 198 | for(k=1;k<=size(iden);k++) |
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| 199 | { |
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| 200 | for(i=1;i<=size(iden[k]);i++) |
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| 201 | { |
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| 202 | if(defined(S)){kill S;} |
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| 203 | def S=re[2][iden[k][i][1]]; |
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| 204 | setring S; |
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| 205 | if((!v[k])&&(defined(EList))) |
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| 206 | { |
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| 207 | if(defined(II)){kill II;} |
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| 208 | //--- we might be embedded in a non-trivial BO[1] |
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| 209 | //--- take this into account when forming the jacobi-determinant |
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| 210 | ideal II=jacobDet(BO[5],BO[1]); |
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| 211 | if(size(II)!=0) |
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| 212 | { |
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| 213 | v[k]=ordE(II,EList[iden[k][i][2]],BO[1])+1; |
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| 214 | } |
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| 215 | } |
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| 216 | setring R; |
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| 217 | } |
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| 218 | } |
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| 219 | return(v); |
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| 220 | } |
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| 221 | example |
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[1e1ec4] | 222 | {"EXAMPLE:"; echo = 2; |
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| 223 | ring R=0,(x,y,z),dp; |
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| 224 | ideal I=(x-y)*(x-z)*(y-z)-z4; |
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| 225 | list re=resolve(I,1); |
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| 226 | list iden=prepEmbDiv(re); |
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| 227 | intvec v=computeV(re, iden); |
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| 228 | v; |
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[2e6eac2] | 229 | } |
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| 230 | |
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| 231 | /////////////////////////////////////////////////////////////////////////////// |
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[f27ab81] | 232 | static proc jacobDet(ideal I, ideal J) |
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[2e6eac2] | 233 | "Internal procedure - no help and no example available |
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| 234 | " |
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| 235 | { |
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| 236 | //--- Returns the Jacobian determinant of the morphism |
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| 237 | //--- K[x_1,...,x_m]--->K[y_1,...,y_n]/J defined by x_i ---> I_i. |
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| 238 | //--- Let basering=K[y_1,...,y_n], l=n-dim(basering/J), |
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| 239 | //--- I=<I_1,...,I_m>, J=<J_1,...,J_r> |
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| 240 | //--- For each subset v in {1,...,n} of l elements and |
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| 241 | //--- w in {1,...,r} of l elements |
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| 242 | //--- let K_v,w be the ideal generated by the n-l-minors of the matrix |
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| 243 | //--- (diff(I_i,y_j)+ |
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| 244 | //--- \sum_k diff(I_i,y_v[k])*diff(J_w[k],y_j))_{j not in v multiplied with |
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| 245 | //--- the determinant of (diff(J_w[i],y_v[j])) |
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| 246 | //--- the sum of all such ideals K_v,w plus J is returned. |
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| 247 | |
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| 248 | //---------------------------------------------------------------------------- |
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| 249 | // Initialization |
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| 250 | //---------------------------------------------------------------------------- |
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| 251 | int n=nvars(basering); |
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| 252 | int i,j,k; |
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| 253 | intvec u,v,w,x; |
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| 254 | matrix MI[ncols(I)][n]=jacob(I); |
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| 255 | matrix N=unitmat(n); |
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| 256 | matrix L; |
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| 257 | ideal K=J; |
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| 258 | if(size(J)==0) |
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| 259 | { |
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| 260 | K=minor(MI,n); |
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| 261 | } |
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| 262 | |
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| 263 | //--------------------------------------------------------------------------- |
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| 264 | // Do calculation as described above. |
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| 265 | // separately for case size(J)=1 |
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| 266 | //--------------------------------------------------------------------------- |
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| 267 | if(size(J)==1) |
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| 268 | { |
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| 269 | matrix MJ[ncols(J)][n]=jacob(J); |
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| 270 | N=concat(N,transpose(MJ)); |
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| 271 | v=1..n; |
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| 272 | for(i=1;i<=n;i++) |
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| 273 | { |
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| 274 | L=transpose(permcol(N,i,n+1)); |
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| 275 | if(i==1){w=2..n;} |
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| 276 | if(i==n){w=1..n-1;} |
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| 277 | if((i!=1)&&(i!=n)){w=1..i-1,i+1..n;} |
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| 278 | L=submat(L,v,w); |
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| 279 | L=MI*L; |
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| 280 | K=K+minor(L,n-1)*MJ[1,i]; |
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| 281 | } |
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| 282 | } |
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| 283 | if(size(J)>1) |
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| 284 | { |
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| 285 | matrix MJ[ncols(J)][n]=jacob(J); |
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| 286 | matrix SMJ; |
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| 287 | N=concat(N,transpose(MJ)); |
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| 288 | ideal Jstd=std(J); |
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| 289 | int l=n-dim(Jstd); |
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| 290 | int r=ncols(J); |
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| 291 | list L1=indexSet(n,l); |
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| 292 | list L2=indexSet(r,l); |
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| 293 | for(i=1;i<=size(L1);i++) |
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| 294 | { |
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| 295 | for(j=1;j<=size(L2);j++) |
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| 296 | { |
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| 297 | for(k=1;k<=size(L1[i]);k++) |
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| 298 | { |
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| 299 | if(L1[i][k]){v[size(v)+1]=k;} |
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| 300 | } |
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| 301 | v=v[2..size(v)]; |
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| 302 | for(k=1;k<=size(L2[j]);k++) |
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| 303 | { |
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| 304 | if(L2[j][k]){w[size(w)+1]=k;} |
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| 305 | } |
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| 306 | w=w[2..size(w)]; |
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| 307 | SMJ=submat(MJ,w,v); |
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| 308 | L=N; |
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| 309 | for(k=1;k<=l;k++) |
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| 310 | { |
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| 311 | L=permcol(L,v[k],n+w[k]); |
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| 312 | } |
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| 313 | u=1..n; |
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| 314 | x=1..n; |
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| 315 | v=sort(v)[1]; |
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| 316 | for(k=l;k>=1;k--) |
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| 317 | { |
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| 318 | if(v[k]) |
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| 319 | { |
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| 320 | u=deleteInt(u,v[k],1); |
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| 321 | } |
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| 322 | } |
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| 323 | L=transpose(submat(L,u,x)); |
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| 324 | L=MI*L; |
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| 325 | K=K+minor(L,n-l)*det(SMJ); |
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| 326 | } |
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| 327 | } |
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| 328 | } |
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| 329 | return(K); |
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| 330 | } |
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| 331 | |
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| 332 | /////////////////////////////////////////////////////////////////////////////// |
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[f27ab81] | 333 | static proc computeH(ideal h,list re,list DL) |
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[2e6eac2] | 334 | "Internal procedure - no help and no example available |
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| 335 | " |
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| 336 | { |
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| 337 | //--- additional procedure to computeV, allows |
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| 338 | //--- computation for polynomial x volume form |
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| 339 | //--- by computing the contribution of the polynomial h |
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| 340 | //--- Note: DL is output of prepEmbDiv |
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| 341 | |
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| 342 | //---------------------------------------------------------------------------- |
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| 343 | // Initialization |
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| 344 | //---------------------------------------------------------------------------- |
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| 345 | def R=basering; |
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| 346 | ideal II=h; |
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| 347 | list iden=DL; |
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| 348 | def T=re[2][1]; |
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| 349 | setring T; |
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| 350 | int i,k; |
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| 351 | intvec v; |
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| 352 | v[size(iden)]=0; |
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| 353 | if(deg(II[1])==0){return(v);} |
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| 354 | //---------------------------------------------------------------------------- |
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| 355 | // Run through all exceptional divisors |
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| 356 | //---------------------------------------------------------------------------- |
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| 357 | for(k=1;k<=size(iden);k++) |
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| 358 | { |
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| 359 | for(i=1;i<=size(iden[k]);i++) |
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| 360 | { |
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| 361 | if(defined(S)){kill S;} |
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| 362 | def S=re[2][iden[k][i][1]]; |
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| 363 | setring S; |
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| 364 | if((!v[k])&&(defined(EList))) |
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| 365 | { |
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| 366 | if(defined(JJ)){kill JJ;} |
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| 367 | if(defined(phi)){kill phi;} |
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| 368 | map phi=T,BO[5]; |
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| 369 | ideal JJ=phi(II); |
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| 370 | if(size(JJ)!=0) |
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| 371 | { |
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| 372 | v[k]=ordE(JJ,EList[iden[k][i][2]],BO[1]); |
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| 373 | } |
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| 374 | } |
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| 375 | setring R; |
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| 376 | } |
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| 377 | } |
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| 378 | return(v); |
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| 379 | } |
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| 380 | |
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| 381 | ////////////////////////////////////////////////////////////////////////////// |
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[1e1ec4] | 382 | proc computeN(list re,list DL) |
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| 383 | "USAGE: computeN(L,DL); |
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| 384 | L = list of rings |
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| 385 | DL = divisor list |
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| 386 | ASSUME: L has structure of output of resolve |
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| 387 | DL has structure of output of prepEmbDiv |
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| 388 | RETURN: intvec, i-th entry is multiplicity of i-th divisor |
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| 389 | in total transform under resolution |
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| 390 | EXAMPLE: example computeN; |
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[2e6eac2] | 391 | " |
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| 392 | { |
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| 393 | //--- computes for every (Q-irred.) divisor E_i its multiplicity in f \circ pi |
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| 394 | //--- DL is output of prepEmbDiv |
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| 395 | |
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| 396 | //---------------------------------------------------------------------------- |
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| 397 | // Initialization |
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| 398 | //---------------------------------------------------------------------------- |
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| 399 | def R=basering; |
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| 400 | list iden=DL; |
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| 401 | def T=re[2][1]; |
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| 402 | setring T; |
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| 403 | ideal J=BO[2]; |
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| 404 | int i,k; |
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| 405 | intvec v; |
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| 406 | v[size(iden)]=0; |
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| 407 | //---------------------------------------------------------------------------- |
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| 408 | // Run through all exceptional divisors |
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| 409 | //---------------------------------------------------------------------------- |
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| 410 | for(k=1;k<=size(iden);k++) |
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| 411 | { |
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| 412 | for(i=1;i<=size(iden[k]);i++) |
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| 413 | { |
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| 414 | if(defined(S)){kill S;} |
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| 415 | def S=re[2][iden[k][i][1]]; |
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| 416 | setring S; |
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| 417 | if((!v[k])&&(defined(EList))) |
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| 418 | { |
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| 419 | if(defined(II)){kill II;} |
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| 420 | if(defined(phi)){kill phi;} |
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| 421 | map phi=T,BO[5]; |
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| 422 | ideal II=phi(J); |
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| 423 | if(size(II)!=0) |
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| 424 | { |
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| 425 | v[k]=ordE(II,EList[iden[k][i][2]],BO[1]); |
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| 426 | } |
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| 427 | } |
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| 428 | setring R; |
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| 429 | } |
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| 430 | } |
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| 431 | return(v); |
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| 432 | } |
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| 433 | example |
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| 434 | {"EXAMPLE:"; |
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| 435 | echo = 2; |
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| 436 | ring R=0,(x,y,z),dp; |
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| 437 | ideal I=(x-y)*(x-z)*(y-z)-z4; |
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| 438 | list re=resolve(I,1); |
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[1e1ec4] | 439 | list iden=prepEmbDiv(re); |
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| 440 | intvec v=computeN(re,iden); |
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[2e6eac2] | 441 | v; |
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| 442 | } |
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| 443 | ////////////////////////////////////////////////////////////////////////////// |
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[f27ab81] | 444 | static proc countEijk(list re,list iden,intvec iv,list #) |
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[2e6eac2] | 445 | "Internal procedure - no help and no example available |
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| 446 | " |
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| 447 | { |
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| 448 | //--- count the number of points in the intersection of 3 exceptional |
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| 449 | //--- hyperplanes (of dimension 2) - one of them is allowed to be a component |
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| 450 | //--- of the strict transform |
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| 451 | |
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| 452 | //---------------------------------------------------------------------------- |
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| 453 | // Initialization |
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| 454 | //---------------------------------------------------------------------------- |
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| 455 | int i,j,k,comPa,numPts,localCase; |
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| 456 | intvec ituple,jtuple,ktuple; |
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| 457 | list chList,tmpList; |
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| 458 | def R=basering; |
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| 459 | if(size(#)>0) |
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| 460 | { |
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| 461 | if(string(#[1])=="local") |
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| 462 | { |
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| 463 | localCase=1; |
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| 464 | } |
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| 465 | } |
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| 466 | //---------------------------------------------------------------------------- |
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| 467 | // Find common charts |
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| 468 | //---------------------------------------------------------------------------- |
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| 469 | for(i=1;i<=size(iden[iv[1]]);i++) |
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| 470 | { |
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| 471 | //--- find common charts - only for final charts |
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| 472 | if(defined(S)) {kill S;} |
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| 473 | def S=re[2][iden[iv[1]][i][1]]; |
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| 474 | setring S; |
---|
| 475 | if(!defined(EList)) |
---|
| 476 | { |
---|
| 477 | i++; |
---|
| 478 | setring R; |
---|
| 479 | continue; |
---|
| 480 | } |
---|
| 481 | setring R; |
---|
| 482 | kill ituple,jtuple,ktuple; |
---|
| 483 | intvec ituple=iden[iv[1]][i]; |
---|
| 484 | intvec jtuple=findInIVList(1,ituple[1],iden[iv[2]]); |
---|
| 485 | intvec ktuple=findInIVList(1,ituple[1],iden[iv[3]]); |
---|
| 486 | if((size(jtuple)!=1)&&(size(ktuple)!=1)) |
---|
| 487 | { |
---|
| 488 | //--- chList contains all information about the common charts, |
---|
| 489 | //--- each entry represents a chart and contains three intvecs from iden |
---|
| 490 | //--- one for each E_l |
---|
| 491 | kill tmpList; |
---|
| 492 | list tmpList=ituple,jtuple,ktuple; |
---|
| 493 | chList[size(chList)+1]=tmpList; |
---|
| 494 | i++; |
---|
| 495 | if(i<=size(iden[iv[1]])) |
---|
| 496 | { |
---|
| 497 | continue; |
---|
| 498 | } |
---|
| 499 | else |
---|
| 500 | { |
---|
| 501 | break; |
---|
| 502 | } |
---|
| 503 | } |
---|
| 504 | } |
---|
| 505 | if(size(chList)==0) |
---|
| 506 | { |
---|
| 507 | //--- no common chart !!! |
---|
| 508 | return(int(0)); |
---|
| 509 | } |
---|
| 510 | //---------------------------------------------------------------------------- |
---|
| 511 | // Count points in common charts |
---|
| 512 | //---------------------------------------------------------------------------- |
---|
| 513 | for(i=1;i<=size(chList);i++) |
---|
| 514 | { |
---|
| 515 | //--- run through all common charts |
---|
| 516 | if(defined(S)) { kill S;} |
---|
| 517 | def S=re[2][chList[i][1][1]]; |
---|
| 518 | setring S; |
---|
| 519 | //--- intersection in this chart |
---|
| 520 | if(defined(interId)){kill interId;} |
---|
| 521 | if(localCase==1) |
---|
| 522 | { |
---|
| 523 | //--- in this case we need to intersect with \pi^-1(0) |
---|
| 524 | ideal interId=EList[chList[i][1][2]]+EList[chList[i][2][2]] |
---|
| 525 | +EList[chList[i][3][2]]+BO[5]; |
---|
| 526 | } |
---|
| 527 | else |
---|
| 528 | { |
---|
| 529 | ideal interId=EList[chList[i][1][2]]+EList[chList[i][2][2]] |
---|
| 530 | +EList[chList[i][3][2]]; |
---|
| 531 | } |
---|
| 532 | interId=std(interId); |
---|
| 533 | if(defined(otherId)) {kill otherId;} |
---|
| 534 | ideal otherId=1; |
---|
| 535 | for(j=1;j<i;j++) |
---|
| 536 | { |
---|
| 537 | //--- run through the previously computed ones |
---|
| 538 | if(defined(opath)){kill opath;} |
---|
| 539 | def opath=imap(re[2][chList[j][1][1]],path); |
---|
| 540 | comPa=1; |
---|
| 541 | while(opath[1,comPa]==path[1,comPa]) |
---|
| 542 | { |
---|
| 543 | comPa++; |
---|
| 544 | if((comPa>ncols(path))||(comPa>ncols(opath))) break; |
---|
| 545 | } |
---|
| 546 | comPa=int(leadcoef(path[1,comPa-1])); |
---|
| 547 | otherId=otherId+interId; |
---|
| 548 | otherId=intersect(otherId, |
---|
| 549 | fetchInTree(re,chList[j][1][1], |
---|
| 550 | comPa,chList[i][1][1],"interId",iden)); |
---|
| 551 | } |
---|
| 552 | otherId=std(otherId); |
---|
| 553 | //--- do not count each point more than once |
---|
| 554 | interId=sat(interId,otherId)[1]; |
---|
| 555 | export(interId); |
---|
| 556 | if(dim(interId)>0) |
---|
| 557 | { |
---|
| 558 | ERROR("CountEijk: intersection not zerodimensional"); |
---|
| 559 | } |
---|
| 560 | //--- add the remaining number of points to the total point count numPts |
---|
| 561 | numPts=numPts+vdim(interId); |
---|
| 562 | } |
---|
| 563 | return(numPts); |
---|
| 564 | } |
---|
| 565 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 566 | static proc chiEij(list re, list iden, intvec iv) |
---|
[2e6eac2] | 567 | "Internal procedure - no help and no example available |
---|
| 568 | " |
---|
| 569 | { |
---|
| 570 | //!!! Copy of chiEij_local adjusted for non-local case |
---|
| 571 | //!!! changes must be made in both copies |
---|
| 572 | |
---|
| 573 | //--- compute the Euler characteristic of the intersection |
---|
| 574 | //--- curve of two exceptional hypersurfaces (of dimension 2) |
---|
| 575 | //--- one of which is allowed to be a component of the strict transform |
---|
| 576 | //--- using the formula chi(Eij)=2-2g(Eij) |
---|
| 577 | |
---|
| 578 | //---------------------------------------------------------------------------- |
---|
| 579 | // Initialization |
---|
| 580 | //---------------------------------------------------------------------------- |
---|
| 581 | int i,j,k,chi,g; |
---|
| 582 | intvec ituple,jtuple,inters; |
---|
| 583 | def R=basering; |
---|
| 584 | //---------------------------------------------------------------------------- |
---|
| 585 | // Find a common chart in which they intersect |
---|
| 586 | //---------------------------------------------------------------------------- |
---|
| 587 | for(i=1;i<=size(iden[iv[1]]);i++) |
---|
| 588 | { |
---|
| 589 | //--- find a common chart in which they intersect: only for final charts |
---|
| 590 | if(defined(S)) {kill S;} |
---|
| 591 | def S=re[2][iden[iv[1]][i][1]]; |
---|
| 592 | setring S; |
---|
| 593 | if(!defined(EList)) |
---|
| 594 | { |
---|
| 595 | i++; |
---|
| 596 | setring R; |
---|
| 597 | continue; |
---|
| 598 | } |
---|
| 599 | setring R; |
---|
| 600 | kill ituple,jtuple; |
---|
| 601 | intvec ituple=iden[iv[1]][i]; |
---|
| 602 | intvec jtuple=findInIVList(1,ituple[1],iden[iv[2]]); |
---|
| 603 | if(size(jtuple)==1) |
---|
| 604 | { |
---|
| 605 | if(i<size(iden[iv[1]])) |
---|
| 606 | { |
---|
| 607 | //--- not in this chart |
---|
| 608 | i++; |
---|
| 609 | continue; |
---|
| 610 | } |
---|
| 611 | else |
---|
| 612 | { |
---|
| 613 | if(size(inters)==1) |
---|
| 614 | { |
---|
| 615 | //--- E_i and E_j do not meet at all |
---|
| 616 | return("leer"); |
---|
| 617 | } |
---|
| 618 | else |
---|
| 619 | { |
---|
| 620 | return(chi); |
---|
| 621 | } |
---|
| 622 | } |
---|
| 623 | } |
---|
| 624 | //---------------------------------------------------------------------------- |
---|
| 625 | // Run through common charts and compute the Euler characteristic of |
---|
| 626 | // each component of Eij. |
---|
| 627 | // As soon as a component has been treated in a chart, it will not be used in |
---|
| 628 | // any subsequent charts. |
---|
| 629 | //---------------------------------------------------------------------------- |
---|
| 630 | if(defined(S)) {kill S;} |
---|
| 631 | def S=re[2][ituple[1]]; |
---|
| 632 | setring S; |
---|
| 633 | //--- interId: now all components in this chart, |
---|
| 634 | //--- but we want only new components |
---|
| 635 | if(defined(interId)){kill interId;} |
---|
| 636 | ideal interId=EList[ituple[2]]+EList[jtuple[2]]; |
---|
| 637 | interId=std(interId); |
---|
| 638 | //--- doneId: already considered components |
---|
| 639 | if(defined(doneId)){kill doneId;} |
---|
| 640 | ideal doneId=1; |
---|
| 641 | for(j=2;j<=size(inters);j++) |
---|
| 642 | { |
---|
| 643 | //--- fetch the components which have already been dealt with via fetchInTree |
---|
| 644 | if(defined(opath)) {kill opath;} |
---|
| 645 | def opath=imap(re[2][inters[j]],path); |
---|
| 646 | k=1; |
---|
| 647 | while((k<ncols(opath))&&(k<ncols(path))) |
---|
| 648 | { |
---|
| 649 | if(path[1,k+1]!=opath[1,k+1]) break; |
---|
| 650 | k++; |
---|
| 651 | } |
---|
| 652 | if(defined(comPa)) {kill comPa;} |
---|
| 653 | int comPa=int(leadcoef(path[1,k])); |
---|
| 654 | if(defined(tempId)){kill tempId;} |
---|
| 655 | ideal tempId=fetchInTree(re,inters[j],comPa, |
---|
| 656 | iden[iv[1]][i][1],"interId",iden); |
---|
| 657 | doneId=intersect(doneId,tempId); |
---|
| 658 | kill tempId; |
---|
| 659 | } |
---|
| 660 | //--- only consider new components in interId |
---|
| 661 | interId=sat(interId,doneId)[1]; |
---|
| 662 | if(dim(interId)>1) |
---|
| 663 | { |
---|
| 664 | ERROR("genus_Eij: higher dimensional intersection"); |
---|
| 665 | } |
---|
| 666 | if(dim(interId)>=0) |
---|
| 667 | { |
---|
| 668 | //--- save the index of the current chart for future use |
---|
| 669 | export(interId); |
---|
| 670 | inters[size(inters)+1]=iden[iv[1]][i][1]; |
---|
| 671 | } |
---|
| 672 | BO[1]=std(BO[1]); |
---|
| 673 | if(((dim(interId)<=0)&&(dim(BO[1])>2))|| |
---|
| 674 | ((dim(interId)<0)&&(dim(BO[1])==2))) |
---|
| 675 | { |
---|
| 676 | if(i<size(iden[iv[1]])) |
---|
| 677 | { |
---|
| 678 | //--- not in this chart |
---|
| 679 | setring R; |
---|
| 680 | i++; |
---|
| 681 | continue; |
---|
| 682 | } |
---|
| 683 | else |
---|
| 684 | { |
---|
| 685 | if(size(inters)==1) |
---|
| 686 | { |
---|
| 687 | //--- E_i and E_j do not meet at all |
---|
| 688 | return("leer"); |
---|
| 689 | } |
---|
| 690 | else |
---|
| 691 | { |
---|
| 692 | return(chi); |
---|
| 693 | } |
---|
| 694 | } |
---|
| 695 | } |
---|
| 696 | g=genus(interId); |
---|
| 697 | |
---|
| 698 | //--- chi is the Euler characteristic of the (disjoint !!!) union of the |
---|
| 699 | //--- considered components |
---|
| 700 | //--- remark: components are disjoint, because the E_i are normal crossing!!! |
---|
| 701 | |
---|
| 702 | chi=chi+(2-2*g); |
---|
| 703 | } |
---|
| 704 | return(chi); |
---|
| 705 | } |
---|
| 706 | ////////////////////////////////////////////////////////////////////////////// |
---|
| 707 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 708 | static proc chiEij_local(list re, list iden, intvec iv) |
---|
[2e6eac2] | 709 | "Internal procedure - no help and no example available |
---|
| 710 | " |
---|
| 711 | { |
---|
| 712 | //!!! Copy of chiEij adjusted for local case |
---|
| 713 | //!!! changes must be made in both copies |
---|
| 714 | |
---|
| 715 | //--- we have to consider two different cases: |
---|
| 716 | //--- case1: E_i \cap E_j \cap \pi^-1(0) is a curve |
---|
| 717 | //--- compute the Euler characteristic of the intersection |
---|
| 718 | //--- curve of two exceptional hypersurfaces (of dimension 2) |
---|
| 719 | //--- one of which is allowed to be a component of the strict transform |
---|
| 720 | //--- using the formula chi(Eij)=2-2g(Eij) |
---|
| 721 | //--- case2: E_i \cap E_j \cap \pi^-1(0) is a set of points |
---|
| 722 | //--- count the points |
---|
| 723 | |
---|
| 724 | //---------------------------------------------------------------------------- |
---|
| 725 | // Initialization |
---|
| 726 | //---------------------------------------------------------------------------- |
---|
| 727 | int i,j,k,chi,g,points; |
---|
| 728 | intvec ituple,jtuple,inters; |
---|
| 729 | def R=basering; |
---|
| 730 | //---------------------------------------------------------------------------- |
---|
| 731 | // Find a common chart in which they intersect |
---|
| 732 | //---------------------------------------------------------------------------- |
---|
| 733 | for(i=1;i<=size(iden[iv[1]]);i++) |
---|
| 734 | { |
---|
| 735 | //--- find a common chart in which they intersect: only for final charts |
---|
| 736 | if(defined(S)) {kill S;} |
---|
| 737 | def S=re[2][iden[iv[1]][i][1]]; |
---|
| 738 | setring S; |
---|
| 739 | if(!defined(EList)) |
---|
| 740 | { |
---|
| 741 | i++; |
---|
| 742 | setring R; |
---|
| 743 | continue; |
---|
| 744 | } |
---|
| 745 | setring R; |
---|
| 746 | kill ituple,jtuple; |
---|
| 747 | intvec ituple=iden[iv[1]][i]; |
---|
| 748 | intvec jtuple=findInIVList(1,ituple[1],iden[iv[2]]); |
---|
| 749 | if(size(jtuple)==1) |
---|
| 750 | { |
---|
| 751 | if(i<size(iden[iv[1]])) |
---|
| 752 | { |
---|
| 753 | //--- not in this chart |
---|
| 754 | i++; |
---|
| 755 | continue; |
---|
| 756 | } |
---|
| 757 | else |
---|
| 758 | { |
---|
| 759 | if(size(inters)==1) |
---|
| 760 | { |
---|
| 761 | //--- E_i and E_j do not meet at all |
---|
| 762 | return("leer"); |
---|
| 763 | } |
---|
| 764 | else |
---|
| 765 | { |
---|
| 766 | return(chi); |
---|
| 767 | } |
---|
| 768 | } |
---|
| 769 | } |
---|
| 770 | //---------------------------------------------------------------------------- |
---|
| 771 | // Run through common charts and compute the Euler characteristic of |
---|
| 772 | // each component of Eij. |
---|
| 773 | // As soon as a component has been treated in a chart, it will not be used in |
---|
| 774 | // any subsequent charts. |
---|
| 775 | //---------------------------------------------------------------------------- |
---|
| 776 | if(defined(S)) {kill S;} |
---|
| 777 | def S=re[2][ituple[1]]; |
---|
| 778 | setring S; |
---|
| 779 | //--- interId: now all components in this chart, |
---|
| 780 | //--- but we want only new components |
---|
| 781 | if(defined(interId)){kill interId;} |
---|
| 782 | ideal interId=EList[ituple[2]]+EList[jtuple[2]]+BO[5]; |
---|
| 783 | interId=std(interId); |
---|
| 784 | //--- doneId: already considered components |
---|
| 785 | if(defined(doneId)){kill doneId;} |
---|
| 786 | ideal doneId=1; |
---|
| 787 | for(j=2;j<=size(inters);j++) |
---|
| 788 | { |
---|
| 789 | //--- fetch the components which have already been dealt with via fetchInTree |
---|
| 790 | if(defined(opath)) {kill opath;} |
---|
| 791 | def opath=imap(re[2][inters[j]],path); |
---|
| 792 | k=1; |
---|
| 793 | while((k<ncols(opath))&&(k<ncols(path))) |
---|
| 794 | { |
---|
| 795 | if(path[1,k+1]!=opath[1,k+1]) break; |
---|
| 796 | k++; |
---|
| 797 | } |
---|
| 798 | if(defined(comPa)) {kill comPa;} |
---|
| 799 | int comPa=int(leadcoef(path[1,k])); |
---|
| 800 | if(defined(tempId)){kill tempId;} |
---|
| 801 | ideal tempId=fetchInTree(re,inters[j],comPa, |
---|
| 802 | iden[iv[1]][i][1],"interId",iden); |
---|
| 803 | doneId=intersect(doneId,tempId); |
---|
| 804 | kill tempId; |
---|
| 805 | } |
---|
| 806 | //--- only consider new components in interId |
---|
| 807 | interId=sat(interId,doneId)[1]; |
---|
| 808 | if(dim(interId)>1) |
---|
| 809 | { |
---|
| 810 | ERROR("genus_Eij: higher dimensional intersection"); |
---|
| 811 | } |
---|
| 812 | if(dim(interId)>=0) |
---|
| 813 | { |
---|
| 814 | //--- save the index of the current chart for future use |
---|
| 815 | export(interId); |
---|
| 816 | inters[size(inters)+1]=iden[iv[1]][i][1]; |
---|
| 817 | } |
---|
| 818 | BO[1]=std(BO[1]); |
---|
| 819 | if(dim(interId)<0) |
---|
| 820 | { |
---|
| 821 | if(i<size(iden[iv[1]])) |
---|
| 822 | { |
---|
| 823 | //--- not in this chart |
---|
| 824 | setring R; |
---|
| 825 | i++; |
---|
| 826 | continue; |
---|
| 827 | } |
---|
| 828 | else |
---|
| 829 | { |
---|
| 830 | if(size(inters)==1) |
---|
| 831 | { |
---|
| 832 | //--- E_i and E_j do not meet at all |
---|
| 833 | return("leer"); |
---|
| 834 | } |
---|
| 835 | else |
---|
| 836 | { |
---|
| 837 | return(chi); |
---|
| 838 | } |
---|
| 839 | } |
---|
| 840 | } |
---|
| 841 | if((dim(interId)==0)&&(dim(std(BO[1]))>2)) |
---|
| 842 | { |
---|
| 843 | //--- for sets of points the Euler characteristic is just |
---|
| 844 | //--- the number of points |
---|
| 845 | //--- fat points are impossible, since everything is smooth and n.c. |
---|
| 846 | chi=chi+vdim(interId); |
---|
| 847 | points=1; |
---|
| 848 | } |
---|
| 849 | else |
---|
| 850 | { |
---|
| 851 | if(points==1) |
---|
| 852 | { |
---|
| 853 | ERROR("components of intersection do not have same dimension"); |
---|
| 854 | } |
---|
| 855 | g=genus(interId); |
---|
| 856 | //--- chi is the Euler characteristic of the (disjoint !!!) union of the |
---|
| 857 | //--- considered components |
---|
| 858 | //--- remark: components are disjoint, because the E_i are normal crossing!!! |
---|
| 859 | chi=chi+(2-2*g); |
---|
| 860 | } |
---|
| 861 | } |
---|
| 862 | return(chi); |
---|
| 863 | } |
---|
| 864 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 865 | static proc computeChiE(list re, list iden) |
---|
[2e6eac2] | 866 | "Internal procedure - no help and no example available |
---|
| 867 | " |
---|
| 868 | { |
---|
| 869 | //--- compute the Euler characteristic of the exceptional hypersurfaces |
---|
| 870 | //--- (of dimension 2), not considering the components of the strict |
---|
| 871 | //--- transform |
---|
| 872 | |
---|
| 873 | //---------------------------------------------------------------------------- |
---|
| 874 | // Initialization |
---|
| 875 | //---------------------------------------------------------------------------- |
---|
| 876 | int i,j,k,m,thisE,otherE; |
---|
| 877 | def R=basering; |
---|
| 878 | intvec nulliv,chi_temp,kvec; |
---|
| 879 | nulliv[size(iden)]=0; |
---|
| 880 | list chi_E; |
---|
| 881 | for(i=1;i<=size(iden);i++) |
---|
| 882 | { |
---|
| 883 | chi_E[i]=list(); |
---|
| 884 | } |
---|
| 885 | //--------------------------------------------------------------------------- |
---|
| 886 | // Run through the list of charts and compute the Euler characteristic of |
---|
| 887 | // the new exceptional hypersurface and change the values for the old ones |
---|
| 888 | // according to the blow-up which has just been performed |
---|
| 889 | // For initialization reasons, treat the case of the first blow-up separately |
---|
| 890 | //--------------------------------------------------------------------------- |
---|
| 891 | for(i=2;i<=size(re[2]);i++) |
---|
| 892 | { |
---|
| 893 | //--- run through all charts |
---|
| 894 | if(defined(S)){kill S;} |
---|
| 895 | def S=re[2][i]; |
---|
| 896 | setring S; |
---|
| 897 | m=int(leadcoef(path[1,ncols(path)])); |
---|
| 898 | if(defined(Spa)){kill Spa;} |
---|
| 899 | def Spa=re[2][m]; |
---|
| 900 | if(size(BO[4])==1) |
---|
| 901 | { |
---|
| 902 | //--- just one exceptional divisor |
---|
| 903 | thisE=1; |
---|
| 904 | setring Spa; |
---|
| 905 | if(i==2) |
---|
| 906 | { |
---|
| 907 | //--- have not set the initial value of chi(E_1) yet |
---|
| 908 | if(dim(std(cent))==0) |
---|
| 909 | { |
---|
| 910 | //--- center was point ==> new except. div. is a P^2 |
---|
| 911 | list templist=3*vdim(std(BO[1]+cent)),nulliv; |
---|
| 912 | } |
---|
| 913 | else |
---|
| 914 | { |
---|
| 915 | //--- center was curve ==> new except. div. is curve x P^1 |
---|
| 916 | list templist=4-4*genus(BO[1]+cent),nulliv; |
---|
| 917 | } |
---|
| 918 | chi_E[1]=templist; |
---|
| 919 | kill templist; |
---|
| 920 | } |
---|
| 921 | setring S; |
---|
| 922 | i++; |
---|
| 923 | if(i<size(re[2])) |
---|
| 924 | { |
---|
| 925 | continue; |
---|
| 926 | } |
---|
| 927 | else |
---|
| 928 | { |
---|
| 929 | break; |
---|
| 930 | } |
---|
| 931 | } |
---|
| 932 | for(j=1;j<=size(iden);j++) |
---|
| 933 | { |
---|
| 934 | //--- find out which exceptional divisor has just been born |
---|
| 935 | if(inIVList(intvec(i,size(BO[4])),iden[j])) |
---|
| 936 | { |
---|
| 937 | //--- found it |
---|
| 938 | thisE=j; |
---|
| 939 | break; |
---|
| 940 | } |
---|
| 941 | } |
---|
| 942 | //--- now setup new chi and change the previous ones appropriately |
---|
| 943 | setring Spa; |
---|
| 944 | if(size(chi_E[thisE])==0) |
---|
| 945 | { |
---|
| 946 | //--- have not set the initial value of chi(E_thisE) yet |
---|
| 947 | if(dim(std(cent))==0) |
---|
| 948 | { |
---|
| 949 | //--- center was point ==> new except. div. is a P^2 |
---|
| 950 | list templist=3*vdim(std(BO[1]+cent)),nulliv; |
---|
| 951 | } |
---|
| 952 | else |
---|
| 953 | { |
---|
| 954 | //--- center was curve ==> new except. div. is a C x P^1 |
---|
| 955 | list templist=4-4*genus(BO[1]+cent),nulliv; |
---|
| 956 | } |
---|
| 957 | chi_E[thisE]=templist; |
---|
| 958 | kill templist; |
---|
| 959 | } |
---|
| 960 | for(j=1;j<=size(BO[4]);j++) |
---|
| 961 | { |
---|
| 962 | //--- we are in the parent ring ==> thisE is not yet born |
---|
| 963 | //--- all the other E_i have already been initialized, but the chi |
---|
| 964 | //--- might change with the current blow-up at cent |
---|
| 965 | if(BO[6][j]==1) |
---|
| 966 | { |
---|
| 967 | //--- ignore empty sets |
---|
| 968 | j++; |
---|
| 969 | if(j<=size(BO[4])) |
---|
| 970 | { |
---|
| 971 | continue; |
---|
| 972 | } |
---|
| 973 | else |
---|
| 974 | { |
---|
| 975 | break; |
---|
| 976 | } |
---|
| 977 | } |
---|
| 978 | for(k=1;k<=size(iden);k++) |
---|
| 979 | { |
---|
| 980 | //--- find global index of BO[4][j] |
---|
| 981 | if(inIVList(intvec(m,j),iden[k])) |
---|
| 982 | { |
---|
| 983 | otherE=k; |
---|
| 984 | break; |
---|
| 985 | } |
---|
| 986 | } |
---|
| 987 | if(chi_E[otherE][2][thisE]==1) |
---|
| 988 | { |
---|
| 989 | //--- already considered this one |
---|
| 990 | j++; |
---|
| 991 | if(j<=size(BO[4])) |
---|
| 992 | { |
---|
| 993 | continue; |
---|
| 994 | } |
---|
| 995 | else |
---|
| 996 | { |
---|
| 997 | break; |
---|
| 998 | } |
---|
| 999 | } |
---|
| 1000 | //--------------------------------------------------------------------------- |
---|
| 1001 | // update chi according to the formula |
---|
| 1002 | // chi(E_k^transf)=chi(E_k) - chi(C \cap E_k) + chi(E_k \cap E_new) |
---|
| 1003 | // for convenience of implementation, we first compute |
---|
| 1004 | // chi(E_k) - chi(C \cap E_k) |
---|
| 1005 | // and afterwards add the last term chi(E_k \cap E_new) |
---|
| 1006 | //--------------------------------------------------------------------------- |
---|
| 1007 | ideal CinE=std(cent+BO[4][j]+BO[1]); // this is C \cap E_k |
---|
| 1008 | if(dim(CinE)==1) |
---|
| 1009 | { |
---|
| 1010 | //--- center meets E_k in a curve |
---|
| 1011 | chi_temp[otherE]=chi_E[otherE][1]-(2-2*genus(CinE)); |
---|
| 1012 | } |
---|
| 1013 | if(dim(CinE)==0) |
---|
| 1014 | { |
---|
| 1015 | //--- center meets E_k in points |
---|
| 1016 | chi_temp[otherE]=chi_E[otherE][1]-vdim(std(CinE)); |
---|
| 1017 | } |
---|
| 1018 | kill CinE; |
---|
| 1019 | setring S; |
---|
| 1020 | //--- now we are back in the i-th ring in the list |
---|
| 1021 | ideal CinE=std(BO[4][j]+BO[4][size(BO[4])]+BO[1]); |
---|
| 1022 | // this is E_k \cap E_new |
---|
| 1023 | if(dim(CinE)==1) |
---|
| 1024 | { |
---|
| 1025 | //--- if the two divisors meet, they meet in a curve |
---|
| 1026 | chi_E[otherE][1]=chi_temp[otherE]+(2-2*genus(CinE)); |
---|
| 1027 | chi_E[otherE][2][thisE]=1; // this blow-up of E_k is done |
---|
| 1028 | } |
---|
| 1029 | kill CinE; |
---|
| 1030 | setring Spa; |
---|
| 1031 | } |
---|
| 1032 | } |
---|
| 1033 | setring R; |
---|
| 1034 | return(chi_E); |
---|
| 1035 | } |
---|
| 1036 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 1037 | static proc computeChiE_local(list re, list iden) |
---|
[2e6eac2] | 1038 | "Internal procedure - no help and no example available |
---|
| 1039 | " |
---|
| 1040 | { |
---|
| 1041 | //--- compute the Euler characteristic of the intersection of the |
---|
| 1042 | //--- exceptional hypersurfaces with \pi^-1(0) which can be of |
---|
| 1043 | //--- dimension 1 or 2 - not considering the components of the strict |
---|
| 1044 | //--- transform |
---|
| 1045 | |
---|
| 1046 | //---------------------------------------------------------------------------- |
---|
| 1047 | // Initialization |
---|
| 1048 | //---------------------------------------------------------------------------- |
---|
| 1049 | int i,j,k,aa,m,n,thisE,otherE; |
---|
| 1050 | def R=basering; |
---|
| 1051 | intvec nulliv,chi_temp,kvec,dimEi,endiv; |
---|
| 1052 | nulliv[size(iden)]=0; |
---|
| 1053 | dimEi[size(iden)]=0; |
---|
| 1054 | endiv[size(re[2])]=0; |
---|
| 1055 | list chi_E; |
---|
| 1056 | for(i=1;i<=size(iden);i++) |
---|
| 1057 | { |
---|
| 1058 | chi_E[i]=list(); |
---|
| 1059 | } |
---|
| 1060 | //--------------------------------------------------------------------------- |
---|
| 1061 | // Run through the list of charts and compute the Euler characteristic of |
---|
| 1062 | // the new exceptional hypersurface and change the values for the old ones |
---|
| 1063 | // according to the blow-up which has just been performed |
---|
| 1064 | // For initialization reasons, treat the case of the first blow-up separately |
---|
| 1065 | //--------------------------------------------------------------------------- |
---|
| 1066 | for(i=2;i<=size(re[2]);i++) |
---|
| 1067 | { |
---|
| 1068 | //--- run through all charts |
---|
| 1069 | if(defined(S)){kill S;} |
---|
| 1070 | def S=re[2][i]; |
---|
| 1071 | setring S; |
---|
| 1072 | if(defined(EList)) |
---|
| 1073 | { |
---|
| 1074 | endiv[i]=1; |
---|
| 1075 | } |
---|
| 1076 | m=int(leadcoef(path[1,ncols(path)])); |
---|
| 1077 | if(defined(Spa)){kill Spa;} |
---|
| 1078 | def Spa=re[2][m]; |
---|
| 1079 | if(size(BO[4])==1) |
---|
| 1080 | { |
---|
| 1081 | //--- just one exceptional divisor |
---|
| 1082 | thisE=1; |
---|
| 1083 | setring Spa; |
---|
| 1084 | if(i==2) |
---|
| 1085 | { |
---|
| 1086 | //--- have not set the initial value of chi(E_1) yet |
---|
| 1087 | //--- in the local case, we need to know whether the center contains 0 |
---|
| 1088 | if(size(reduce(cent,std(maxideal(1))))!=0) |
---|
| 1089 | { |
---|
| 1090 | //--- first center does not meet 0 |
---|
| 1091 | list templist=0,nulliv; |
---|
| 1092 | dimEi[1]=-1; |
---|
| 1093 | } |
---|
| 1094 | else |
---|
| 1095 | { |
---|
| 1096 | if(dim(std(cent))==0) |
---|
| 1097 | { |
---|
| 1098 | //--- center was point ==> new except. div. is a P^2 |
---|
| 1099 | list templist=3*vdim(std(BO[1]+cent)),nulliv; |
---|
| 1100 | dimEi[1]=2; |
---|
| 1101 | } |
---|
| 1102 | else |
---|
| 1103 | { |
---|
| 1104 | //--- center was curve ==> intersection of new exceptional divisor |
---|
| 1105 | //--- with \pi^-1(0) is a curve, namely P^1 |
---|
| 1106 | setring S; |
---|
| 1107 | list templist=2,nulliv; |
---|
| 1108 | dimEi[1]=1; |
---|
| 1109 | } |
---|
| 1110 | } |
---|
| 1111 | chi_E[1]=templist; |
---|
| 1112 | kill templist; |
---|
| 1113 | } |
---|
| 1114 | setring S; |
---|
| 1115 | i++; |
---|
| 1116 | if(i<size(re[2])) |
---|
| 1117 | { |
---|
| 1118 | continue; |
---|
| 1119 | } |
---|
| 1120 | else |
---|
| 1121 | { |
---|
| 1122 | break; |
---|
| 1123 | } |
---|
| 1124 | } |
---|
| 1125 | for(j=1;j<=size(iden);j++) |
---|
| 1126 | { |
---|
| 1127 | //--- find out which exceptional divisor has just been born |
---|
| 1128 | if(inIVList(intvec(i,size(BO[4])),iden[j])) |
---|
| 1129 | { |
---|
| 1130 | //--- found it |
---|
| 1131 | thisE=j; |
---|
| 1132 | break; |
---|
| 1133 | } |
---|
| 1134 | } |
---|
| 1135 | //--- now setup new chi and change the previous ones appropriately |
---|
| 1136 | setring Spa; |
---|
| 1137 | if(size(chi_E[thisE])==0) |
---|
| 1138 | { |
---|
| 1139 | //--- have not set the initial value of chi(E_thisE) yet |
---|
| 1140 | if(deg(std(cent+BO[5])[1])==0) |
---|
| 1141 | { |
---|
| 1142 | if(dim(std(cent))==0) |
---|
| 1143 | { |
---|
| 1144 | //--- \pi^-1(0) does not meet the Q-point cent |
---|
| 1145 | list templist=0,nulliv; |
---|
| 1146 | dimEi[thisE]=-1; |
---|
| 1147 | } |
---|
| 1148 | //--- if cent is a curve, the intersection point might simply be outside |
---|
| 1149 | //--- of this chart!!! |
---|
| 1150 | } |
---|
| 1151 | else |
---|
| 1152 | { |
---|
| 1153 | if(dim(std(cent))==0) |
---|
| 1154 | { |
---|
| 1155 | //--- center was point ==> new except. div. is a P^2 |
---|
| 1156 | list templist=3*vdim(std(BO[1]+cent)),nulliv; |
---|
| 1157 | dimEi[thisE]=2; |
---|
| 1158 | } |
---|
| 1159 | else |
---|
| 1160 | { |
---|
| 1161 | //--- center was curve ==> new except. div. is a C x P^1 |
---|
| 1162 | if(dim(std(cent+BO[5]))==1) |
---|
| 1163 | { |
---|
| 1164 | //--- whole curve is in \pi^-1(0) |
---|
| 1165 | list templist=4-4*genus(BO[1]+cent),nulliv; |
---|
| 1166 | dimEi[thisE]=2; |
---|
| 1167 | } |
---|
| 1168 | else |
---|
| 1169 | { |
---|
| 1170 | //--- curve meets \pi^-1(0) in points |
---|
| 1171 | //--- in S, the intersection will be a curve!!! |
---|
| 1172 | setring S; |
---|
| 1173 | list templist=2-2*genus(BO[1]+BO[4][size(BO[4])]+BO[5]),nulliv; |
---|
| 1174 | dimEi[thisE]=1; |
---|
| 1175 | setring Spa; |
---|
| 1176 | } |
---|
| 1177 | } |
---|
| 1178 | } |
---|
| 1179 | if(defined(templist)) |
---|
| 1180 | { |
---|
| 1181 | chi_E[thisE]=templist; |
---|
[f4c2ba] | 1182 | kill templist; |
---|
[2e6eac2] | 1183 | } |
---|
| 1184 | } |
---|
| 1185 | for(j=1;j<=size(BO[4]);j++) |
---|
| 1186 | { |
---|
| 1187 | //--- we are in the parent ring ==> thisE is not yet born |
---|
| 1188 | //--- all the other E_i have already been initialized, but the chi |
---|
| 1189 | //--- might change with the current blow-up at cent |
---|
| 1190 | if(BO[6][j]==1) |
---|
| 1191 | { |
---|
| 1192 | //--- ignore empty sets |
---|
| 1193 | j++; |
---|
| 1194 | if(j<=size(BO[4])) |
---|
| 1195 | { |
---|
| 1196 | continue; |
---|
| 1197 | } |
---|
| 1198 | else |
---|
| 1199 | { |
---|
| 1200 | break; |
---|
| 1201 | } |
---|
| 1202 | } |
---|
| 1203 | for(k=1;k<=size(iden);k++) |
---|
| 1204 | { |
---|
| 1205 | //--- find global index of BO[4][j] |
---|
| 1206 | if(inIVList(intvec(m,j),iden[k])) |
---|
| 1207 | { |
---|
| 1208 | otherE=k; |
---|
| 1209 | break; |
---|
| 1210 | } |
---|
| 1211 | } |
---|
| 1212 | if(dimEi[otherE]<=1) |
---|
| 1213 | { |
---|
| 1214 | //--- dimEi[otherE]==-1: center leading to this E does not meet \pi^-1(0) |
---|
| 1215 | //--- dimEi[otherE]== 0: center leading to this E does not meet \pi^-1(0) |
---|
| 1216 | //--- in any previously visited charts |
---|
| 1217 | //--- maybe in some other branch later, but has nothing |
---|
| 1218 | //--- to do with this center |
---|
| 1219 | //--- dimEi[otherE]== 1: E \cap \pi^-1(0) is curve |
---|
| 1220 | //--- ==> chi is birational invariant |
---|
| 1221 | j++; |
---|
| 1222 | if(j<=size(BO[4])) |
---|
| 1223 | { |
---|
| 1224 | continue; |
---|
| 1225 | } |
---|
| 1226 | break; |
---|
| 1227 | } |
---|
| 1228 | if(chi_E[otherE][2][thisE]==1) |
---|
| 1229 | { |
---|
| 1230 | //--- already considered this one |
---|
| 1231 | j++; |
---|
| 1232 | if(j<=size(BO[4])) |
---|
| 1233 | { |
---|
| 1234 | continue; |
---|
| 1235 | } |
---|
| 1236 | else |
---|
| 1237 | { |
---|
| 1238 | break; |
---|
| 1239 | } |
---|
| 1240 | } |
---|
| 1241 | //--------------------------------------------------------------------------- |
---|
| 1242 | // update chi according to the formula |
---|
| 1243 | // chi(E_k^transf)=chi(E_k) - chi(C \cap E_k) + chi(E_k \cap E_new) |
---|
| 1244 | // for convenience of implementation, we first compute |
---|
| 1245 | // chi(E_k) - chi(C \cap E_k) |
---|
| 1246 | // and afterwards add the last term chi(E_k \cap E_new) |
---|
| 1247 | //--------------------------------------------------------------------------- |
---|
| 1248 | ideal CinE=std(cent+BO[4][j]+BO[1]); // this is C \cap E_k |
---|
| 1249 | if(dim(CinE)==1) |
---|
| 1250 | { |
---|
| 1251 | //--- center meets E_k in a curve |
---|
| 1252 | chi_temp[otherE]=chi_E[otherE][1]-(2-2*genus(CinE)); |
---|
| 1253 | } |
---|
| 1254 | if(dim(CinE)==0) |
---|
| 1255 | { |
---|
| 1256 | //--- center meets E_k in points |
---|
| 1257 | chi_temp[otherE]=chi_E[otherE][1]-vdim(std(CinE)); |
---|
| 1258 | } |
---|
| 1259 | kill CinE; |
---|
| 1260 | setring S; |
---|
| 1261 | //--- now we are back in the i-th ring in the list |
---|
| 1262 | ideal CinE=std(BO[4][j]+BO[4][size(BO[4])]+BO[1]); |
---|
| 1263 | // this is E_k \cap E_new |
---|
| 1264 | if(dim(CinE)==1) |
---|
| 1265 | { |
---|
| 1266 | //--- if the two divisors meet, they meet in a curve |
---|
[f4c2ba] | 1267 | chi_E[otherE][1]=chi_temp[otherE][1]+(2-2*genus(CinE)); |
---|
[2e6eac2] | 1268 | chi_E[otherE][2][thisE]=1; // this blow-up of E_k is done |
---|
| 1269 | } |
---|
| 1270 | kill CinE; |
---|
| 1271 | setring Spa; |
---|
| 1272 | } |
---|
| 1273 | } |
---|
| 1274 | //--- we still need to clean-up the 1-dimensional E_i \cap \pi^-1(0) |
---|
| 1275 | for(i=1;i<=size(dimEi);i++) |
---|
| 1276 | { |
---|
| 1277 | if(dimEi[i]!=1) |
---|
| 1278 | { |
---|
| 1279 | //--- not 1-dimensional ==> skip |
---|
| 1280 | i++; |
---|
| 1281 | if(i>size(dimEi)) break; |
---|
| 1282 | continue; |
---|
| 1283 | } |
---|
| 1284 | if(defined(myCharts)) {kill myCharts;} |
---|
| 1285 | intvec myCharts; |
---|
| 1286 | chi_E[i]=0; |
---|
| 1287 | for(j=1;j<=size(re[2]);j++) |
---|
| 1288 | { |
---|
| 1289 | if(endiv[j]==0) |
---|
| 1290 | { |
---|
| 1291 | //--- not an endChart ==> skip |
---|
| 1292 | j++; |
---|
| 1293 | if(j>size(re[2])) break; |
---|
| 1294 | continue; |
---|
| 1295 | } |
---|
| 1296 | if(defined(mtuple)) {kill mtuple;} |
---|
| 1297 | intvec mtuple=findInIVList(1,j,iden[i]); |
---|
| 1298 | if(size(mtuple)==1) |
---|
| 1299 | { |
---|
| 1300 | //-- nothing to do with this Ei ==> skip |
---|
| 1301 | j++; |
---|
| 1302 | if(j>size(re[2])) break; |
---|
| 1303 | continue; |
---|
| 1304 | } |
---|
| 1305 | myCharts[size(myCharts)+1]=j; |
---|
| 1306 | if(defined(S)){kill S;} |
---|
| 1307 | def S=re[2][j]; |
---|
| 1308 | setring S; |
---|
| 1309 | if(defined(interId)){kill interId;} |
---|
| 1310 | //--- all components |
---|
| 1311 | ideal interId=std(BO[4][mtuple[2]]+BO[5]); |
---|
| 1312 | if(defined(myPts)){kill myPts;} |
---|
| 1313 | ideal myPts=1; |
---|
| 1314 | export(myPts); |
---|
| 1315 | export(interId); |
---|
| 1316 | if(defined(doneId)){kill doneId;} |
---|
| 1317 | if(defined(donePts)){kill donePts;} |
---|
| 1318 | ideal donePts=1; |
---|
| 1319 | ideal doneId=1; |
---|
| 1320 | for(k=2;k<size(myCharts);k++) |
---|
| 1321 | { |
---|
| 1322 | //--- fetch the components which have already been dealt with via fetchInTree |
---|
| 1323 | if(defined(opath)) {kill opath;} |
---|
| 1324 | def opath=imap(re[2][myCharts[k][1]],path); |
---|
| 1325 | aa=1; |
---|
| 1326 | while((aa<ncols(opath))&&(aa<ncols(path))) |
---|
| 1327 | { |
---|
| 1328 | if(path[1,aa+1]!=opath[1,aa+1]) break; |
---|
| 1329 | aa++; |
---|
| 1330 | } |
---|
| 1331 | if(defined(comPa)) {kill comPa;} |
---|
| 1332 | int comPa=int(leadcoef(path[1,aa])); |
---|
| 1333 | if(defined(tempId)){kill tempId;} |
---|
| 1334 | ideal tempId=fetchInTree(re,myCharts[k][1],comPa,j,"interId",iden); |
---|
| 1335 | doneId=intersect(doneId,tempId); |
---|
| 1336 | kill tempId; |
---|
| 1337 | ideal tempId=fetchInTree(re,myCharts[k][1],comPa,j,"myPts",iden); |
---|
| 1338 | donePts=intersect(donePts,tempId); |
---|
| 1339 | kill tempId; |
---|
| 1340 | } |
---|
| 1341 | //--- drop components which have already been dealt with |
---|
| 1342 | interId=sat(interId,doneId)[1]; |
---|
| 1343 | list pr=minAssGTZ(interId); |
---|
| 1344 | myPts=std(interId+doneId); |
---|
| 1345 | for(k=1;k<=size(pr);k++) |
---|
| 1346 | { |
---|
| 1347 | for(n=k+1;n<=size(pr);n++) |
---|
| 1348 | { |
---|
| 1349 | myPts=intersect(myPts,std(pr[k]+pr[n])); |
---|
| 1350 | } |
---|
| 1351 | if(deg(std(pr[k])[1])>0) |
---|
| 1352 | { |
---|
[f4c2ba] | 1353 | chi_E[i][1]=chi_E[i][1]+(2-2*genus(pr[k])); |
---|
[2e6eac2] | 1354 | } |
---|
| 1355 | } |
---|
| 1356 | myPts=sat(myPts,donePts)[1]; |
---|
[f4c2ba] | 1357 | chi_E[i][1]=chi_E[i][1]-vdim(myPts); |
---|
[2e6eac2] | 1358 | } |
---|
| 1359 | } |
---|
| 1360 | setring R; |
---|
| 1361 | return(chi_E); |
---|
| 1362 | } |
---|
| 1363 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 1364 | static proc chi_ast(list re,list iden,list #) |
---|
[2e6eac2] | 1365 | "Internal procedure - no help and no example available |
---|
| 1366 | " |
---|
| 1367 | { |
---|
| 1368 | //--- compute the Euler characteristic of the Ei,Eij,Eijk and the |
---|
| 1369 | //--- corresponding Ei^*,Eij^*,Eijk^* by preparing the input to the |
---|
| 1370 | //--- specialized auxilliary procedures and then recombining the results |
---|
| 1371 | |
---|
| 1372 | //---------------------------------------------------------------------------- |
---|
| 1373 | // Initialization |
---|
| 1374 | //---------------------------------------------------------------------------- |
---|
| 1375 | int i,j,k,g; |
---|
| 1376 | intvec tiv; |
---|
| 1377 | list chi_ijk,chi_ij,chi_i,ast_ijk,ast_ij,ast_i,tmplist,g_ij,emptylist; |
---|
| 1378 | list leererSchnitt; |
---|
| 1379 | def R=basering; |
---|
| 1380 | ring Rhelp=0,@t,dp; |
---|
| 1381 | setring R; |
---|
| 1382 | //---------------------------------------------------------------------------- |
---|
| 1383 | // first compute the chi(Eij) and at the same time |
---|
| 1384 | // check whether E_i \cap E_j is empty |
---|
| 1385 | // the formula is |
---|
| 1386 | // chi_ij=2-2*genus(E_i \cap E_j) |
---|
| 1387 | //---------------------------------------------------------------------------- |
---|
| 1388 | if(size(#)>0) |
---|
| 1389 | { |
---|
| 1390 | "Entering chi_ast"; |
---|
| 1391 | } |
---|
| 1392 | for(i=1;i<=size(iden)-1;i++) |
---|
| 1393 | { |
---|
| 1394 | for(j=i+1;j<=size(iden);j++) |
---|
| 1395 | { |
---|
| 1396 | if(defined(blub)){kill blub;} |
---|
| 1397 | def blub=chiEij(re,iden,intvec(i,j)); |
---|
| 1398 | if(typeof(blub)=="int") |
---|
| 1399 | { |
---|
| 1400 | tmplist=intvec(i,j),blub; |
---|
| 1401 | } |
---|
| 1402 | else |
---|
| 1403 | { |
---|
| 1404 | leererSchnitt[size(leererSchnitt)+1]=intvec(i,j); |
---|
| 1405 | tmplist=intvec(i,j),0; |
---|
| 1406 | } |
---|
| 1407 | chi_ij[size(chi_ij)+1]=tmplist; |
---|
| 1408 | } |
---|
| 1409 | } |
---|
| 1410 | if(size(#)>0) |
---|
| 1411 | { |
---|
| 1412 | "chi_ij computed"; |
---|
| 1413 | } |
---|
| 1414 | //----------------------------------------------------------------------------- |
---|
| 1415 | // compute chi(Eijk)=chi^*(Eijk) by counting the points in the intersection |
---|
| 1416 | // chi_ijk=#(E_i \cap E_j \cap E_k) |
---|
| 1417 | // ast_ijk=chi_ijk |
---|
| 1418 | //----------------------------------------------------------------------------- |
---|
| 1419 | for(i=1;i<=size(iden)-2;i++) |
---|
| 1420 | { |
---|
| 1421 | for(j=i+1;j<=size(iden)-1;j++) |
---|
| 1422 | { |
---|
| 1423 | for(k=j+1;k<=size(iden);k++) |
---|
| 1424 | { |
---|
| 1425 | if(inIVList(intvec(i,j),leererSchnitt)) |
---|
| 1426 | { |
---|
| 1427 | tmplist=intvec(i,j,k),0; |
---|
| 1428 | } |
---|
| 1429 | else |
---|
| 1430 | { |
---|
| 1431 | tmplist=intvec(i,j,k),countEijk(re,iden,intvec(i,j,k)); |
---|
| 1432 | } |
---|
| 1433 | chi_ijk[size(chi_ijk)+1]=tmplist; |
---|
| 1434 | } |
---|
| 1435 | } |
---|
| 1436 | } |
---|
| 1437 | ast_ijk=chi_ijk; |
---|
| 1438 | if(size(#)>0) |
---|
| 1439 | { |
---|
| 1440 | "chi_ijk computed"; |
---|
| 1441 | } |
---|
| 1442 | //---------------------------------------------------------------------------- |
---|
| 1443 | // construct chi(Eij^*) by the formula |
---|
| 1444 | // ast_ij=chi_ij - sum_ijk chi_ijk, |
---|
| 1445 | // where k runs over all indices != i,j |
---|
| 1446 | //---------------------------------------------------------------------------- |
---|
| 1447 | for(i=1;i<=size(chi_ij);i++) |
---|
| 1448 | { |
---|
| 1449 | ast_ij[i]=chi_ij[i]; |
---|
| 1450 | for(k=1;k<=size(chi_ijk);k++) |
---|
| 1451 | { |
---|
| 1452 | if(((chi_ijk[k][1][1]==chi_ij[i][1][1])|| |
---|
| 1453 | (chi_ijk[k][1][2]==chi_ij[i][1][1]))&& |
---|
| 1454 | ((chi_ijk[k][1][2]==chi_ij[i][1][2])|| |
---|
| 1455 | (chi_ijk[k][1][3]==chi_ij[i][1][2]))) |
---|
| 1456 | { |
---|
| 1457 | ast_ij[i][2]=ast_ij[i][2]-chi_ijk[k][2]; |
---|
| 1458 | } |
---|
| 1459 | } |
---|
| 1460 | } |
---|
| 1461 | if(size(#)>0) |
---|
| 1462 | { |
---|
| 1463 | "ast_ij computed"; |
---|
| 1464 | } |
---|
| 1465 | //---------------------------------------------------------------------------- |
---|
| 1466 | // construct ast_i according to the following formulae |
---|
| 1467 | // ast_i=0 if E_i is (Q- resp. C-)component of the strict transform |
---|
| 1468 | // chi_i=3*n if E_i originates from blowing up a Q-point, |
---|
| 1469 | // which consists of n (different) C-points |
---|
| 1470 | // chi_i=2-2g(C) if E_i originates from blowing up a (Q-)curve C |
---|
| 1471 | // (chi_i=n*(2-2g(C_i))=2-2g(C), |
---|
| 1472 | // where C=\cup C_i, C_i \cap C_j = \emptyset) |
---|
| 1473 | // if E_i is not a component of the strict transform, then |
---|
| 1474 | // ast_i=chi_i - sum_{j!=i} ast_ij |
---|
| 1475 | //---------------------------------------------------------------------------- |
---|
| 1476 | for(i=1;i<=size(iden);i++) |
---|
| 1477 | { |
---|
| 1478 | if(defined(S)) {kill S;} |
---|
| 1479 | def S=re[2][iden[i][1][1]]; |
---|
| 1480 | setring S; |
---|
| 1481 | if(iden[i][1][2]>size(BO[4])) |
---|
| 1482 | { |
---|
| 1483 | i--; |
---|
| 1484 | break; |
---|
| 1485 | } |
---|
| 1486 | } |
---|
| 1487 | list idenE=iden; |
---|
| 1488 | while(size(idenE)>i) |
---|
| 1489 | { |
---|
| 1490 | idenE=delete(idenE,size(idenE)); |
---|
| 1491 | } |
---|
| 1492 | list cl=computeChiE(re,idenE); |
---|
| 1493 | for(i=1;i<=size(idenE);i++) |
---|
| 1494 | { |
---|
| 1495 | chi_i[i]=list(intvec(i),cl[i][1]); |
---|
| 1496 | } |
---|
| 1497 | if(size(#)>0) |
---|
| 1498 | { |
---|
| 1499 | "chi_i computed"; |
---|
| 1500 | } |
---|
| 1501 | for(i=1;i<=size(idenE);i++) |
---|
| 1502 | { |
---|
| 1503 | ast_i[i]=chi_i[i]; |
---|
| 1504 | for(j=1;j<=size(ast_ij);j++) |
---|
| 1505 | { |
---|
| 1506 | if((ast_ij[j][1][1]==i)||(ast_ij[j][1][2]==i)) |
---|
| 1507 | { |
---|
| 1508 | ast_i[i][2]=ast_i[i][2]-chi_ij[j][2]; |
---|
| 1509 | } |
---|
| 1510 | } |
---|
| 1511 | for(j=1;j<=size(ast_ijk);j++) |
---|
| 1512 | { |
---|
| 1513 | if((ast_ijk[j][1][1]==i)||(ast_ijk[j][1][2]==i) |
---|
| 1514 | ||(ast_ijk[j][1][3]==i)) |
---|
| 1515 | { |
---|
| 1516 | ast_i[i][2]=ast_i[i][2]+chi_ijk[j][2]; |
---|
| 1517 | } |
---|
| 1518 | } |
---|
| 1519 | } |
---|
| 1520 | for(i=size(idenE)+1;i<=size(iden);i++) |
---|
| 1521 | { |
---|
| 1522 | ast_i[i]=list(intvec(i),0); |
---|
| 1523 | } |
---|
| 1524 | //--- results are in ast_i, ast_ij and ast_ijk |
---|
| 1525 | //--- all are of the form intvec(indices),int(value) |
---|
| 1526 | list result=ast_i,ast_ij,ast_ijk; |
---|
| 1527 | return(result); |
---|
| 1528 | } |
---|
| 1529 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 1530 | static proc chi_ast_local(list re,list iden,list #) |
---|
[2e6eac2] | 1531 | "Internal procedure - no help and no example available |
---|
| 1532 | " |
---|
| 1533 | { |
---|
| 1534 | //--- compute the Euler characteristic of the Ei,Eij,Eijk and the |
---|
| 1535 | //--- corresponding Ei^*,Eij^*,Eijk^* by preparing the input to the |
---|
| 1536 | //--- specialized auxilliary procedures and then recombining the results |
---|
| 1537 | |
---|
| 1538 | //---------------------------------------------------------------------------- |
---|
| 1539 | // Initialization |
---|
| 1540 | //---------------------------------------------------------------------------- |
---|
| 1541 | int i,j,k,g; |
---|
| 1542 | intvec tiv; |
---|
| 1543 | list chi_ijk,chi_ij,chi_i,ast_ijk,ast_ij,ast_i,tmplist,g_ij,emptylist; |
---|
| 1544 | list leererSchnitt; |
---|
| 1545 | def R=basering; |
---|
| 1546 | ring Rhelp=0,@t,dp; |
---|
| 1547 | setring R; |
---|
| 1548 | //---------------------------------------------------------------------------- |
---|
| 1549 | // first compute |
---|
| 1550 | // if E_i \cap E_j \cap \pi^-1(0) is a curve: |
---|
| 1551 | // chi(Eij) and at the same time |
---|
| 1552 | // check whether E_i \cap E_j is empty |
---|
| 1553 | // the formula is |
---|
| 1554 | // chi_ij=2-2*genus(E_i \cap E_j) |
---|
| 1555 | // otherwise (points): |
---|
| 1556 | // chi(E_ij) by counting the points |
---|
| 1557 | //---------------------------------------------------------------------------- |
---|
| 1558 | if(size(#)>0) |
---|
| 1559 | { |
---|
| 1560 | "Entering chi_ast_local"; |
---|
| 1561 | } |
---|
| 1562 | for(i=1;i<=size(iden)-1;i++) |
---|
| 1563 | { |
---|
| 1564 | for(j=i+1;j<=size(iden);j++) |
---|
| 1565 | { |
---|
| 1566 | if(defined(blub)){kill blub;} |
---|
| 1567 | def blub=chiEij_local(re,iden,intvec(i,j)); |
---|
| 1568 | if(typeof(blub)=="int") |
---|
| 1569 | { |
---|
| 1570 | tmplist=intvec(i,j),blub; |
---|
| 1571 | } |
---|
| 1572 | else |
---|
| 1573 | { |
---|
| 1574 | leererSchnitt[size(leererSchnitt)+1]=intvec(i,j); |
---|
| 1575 | tmplist=intvec(i,j),0; |
---|
| 1576 | } |
---|
| 1577 | chi_ij[size(chi_ij)+1]=tmplist; |
---|
| 1578 | } |
---|
| 1579 | } |
---|
| 1580 | if(size(#)>0) |
---|
| 1581 | { |
---|
| 1582 | "chi_ij computed"; |
---|
| 1583 | } |
---|
| 1584 | //----------------------------------------------------------------------------- |
---|
| 1585 | // compute chi(Eijk)=chi^*(Eijk) by counting the points in the intersection |
---|
| 1586 | // chi_ijk=#(E_i \cap E_j \cap E_k \cap \pi^-1(0)) |
---|
| 1587 | // ast_ijk=chi_ijk |
---|
| 1588 | //----------------------------------------------------------------------------- |
---|
| 1589 | for(i=1;i<=size(iden)-2;i++) |
---|
| 1590 | { |
---|
| 1591 | for(j=i+1;j<=size(iden)-1;j++) |
---|
| 1592 | { |
---|
| 1593 | for(k=j+1;k<=size(iden);k++) |
---|
| 1594 | { |
---|
| 1595 | if(inIVList(intvec(i,j),leererSchnitt)) |
---|
| 1596 | { |
---|
| 1597 | tmplist=intvec(i,j,k),0; |
---|
| 1598 | } |
---|
| 1599 | else |
---|
| 1600 | { |
---|
| 1601 | tmplist=intvec(i,j,k),countEijk(re,iden,intvec(i,j,k),"local"); |
---|
| 1602 | } |
---|
| 1603 | chi_ijk[size(chi_ijk)+1]=tmplist; |
---|
| 1604 | } |
---|
| 1605 | } |
---|
| 1606 | } |
---|
| 1607 | ast_ijk=chi_ijk; |
---|
| 1608 | if(size(#)>0) |
---|
| 1609 | { |
---|
| 1610 | "chi_ijk computed"; |
---|
| 1611 | } |
---|
| 1612 | //---------------------------------------------------------------------------- |
---|
| 1613 | // construct chi(Eij^*) by the formula |
---|
| 1614 | // ast_ij=chi_ij - sum_ijk chi_ijk, |
---|
| 1615 | // where k runs over all indices != i,j |
---|
| 1616 | //---------------------------------------------------------------------------- |
---|
| 1617 | for(i=1;i<=size(chi_ij);i++) |
---|
| 1618 | { |
---|
| 1619 | ast_ij[i]=chi_ij[i]; |
---|
| 1620 | for(k=1;k<=size(chi_ijk);k++) |
---|
| 1621 | { |
---|
| 1622 | if(((chi_ijk[k][1][1]==chi_ij[i][1][1])|| |
---|
| 1623 | (chi_ijk[k][1][2]==chi_ij[i][1][1]))&& |
---|
| 1624 | ((chi_ijk[k][1][2]==chi_ij[i][1][2])|| |
---|
| 1625 | (chi_ijk[k][1][3]==chi_ij[i][1][2]))) |
---|
| 1626 | { |
---|
| 1627 | ast_ij[i][2]=ast_ij[i][2]-chi_ijk[k][2]; |
---|
| 1628 | } |
---|
| 1629 | } |
---|
| 1630 | } |
---|
| 1631 | if(size(#)>0) |
---|
| 1632 | { |
---|
| 1633 | "ast_ij computed"; |
---|
| 1634 | } |
---|
| 1635 | //---------------------------------------------------------------------------- |
---|
| 1636 | // construct ast_i according to the following formulae |
---|
| 1637 | // ast_i=0 if E_i is (Q- resp. C-)component of the strict transform |
---|
| 1638 | // if E_i \cap \pi^-1(0) is of dimension 2: |
---|
| 1639 | // chi_i=3*n if E_i originates from blowing up a Q-point, |
---|
| 1640 | // which consists of n (different) C-points |
---|
| 1641 | // chi_i=2-2g(C) if E_i originates from blowing up a (Q-)curve C |
---|
| 1642 | // (chi_i=n*(2-2g(C_i))=2-2g(C), |
---|
| 1643 | // where C=\cup C_i, C_i \cap C_j = \emptyset) |
---|
| 1644 | // if E_i \cap \pi^-1(0) is a curve: |
---|
| 1645 | // use the formula chi_i=2-2*genus(E_i \cap \pi^-1(0)) |
---|
| 1646 | // |
---|
| 1647 | // for E_i not a component of the strict transform we have |
---|
| 1648 | // ast_i=chi_i - sum_{j!=i} ast_ij |
---|
| 1649 | //---------------------------------------------------------------------------- |
---|
| 1650 | for(i=1;i<=size(iden);i++) |
---|
| 1651 | { |
---|
| 1652 | if(defined(S)) {kill S;} |
---|
| 1653 | def S=re[2][iden[i][1][1]]; |
---|
| 1654 | setring S; |
---|
| 1655 | if(iden[i][1][2]>size(BO[4])) |
---|
| 1656 | { |
---|
| 1657 | i--; |
---|
| 1658 | break; |
---|
| 1659 | } |
---|
| 1660 | } |
---|
| 1661 | list idenE=iden; |
---|
| 1662 | while(size(idenE)>i) |
---|
| 1663 | { |
---|
| 1664 | idenE=delete(idenE,size(idenE)); |
---|
| 1665 | } |
---|
| 1666 | list cl=computeChiE_local(re,idenE); |
---|
[f4c2ba] | 1667 | for(i=1;i<=size(cl);i++) |
---|
| 1668 | { |
---|
| 1669 | if(size(cl[i])==0) |
---|
| 1670 | { |
---|
| 1671 | cl[i][1]=0; |
---|
| 1672 | } |
---|
| 1673 | } |
---|
[2e6eac2] | 1674 | for(i=1;i<=size(idenE);i++) |
---|
| 1675 | { |
---|
| 1676 | chi_i[i]=list(intvec(i),cl[i][1]); |
---|
| 1677 | } |
---|
| 1678 | if(size(#)>0) |
---|
| 1679 | { |
---|
| 1680 | "chi_i computed"; |
---|
| 1681 | } |
---|
| 1682 | for(i=1;i<=size(idenE);i++) |
---|
| 1683 | { |
---|
| 1684 | ast_i[i]=chi_i[i]; |
---|
| 1685 | for(j=1;j<=size(ast_ij);j++) |
---|
| 1686 | { |
---|
| 1687 | if((ast_ij[j][1][1]==i)||(ast_ij[j][1][2]==i)) |
---|
| 1688 | { |
---|
| 1689 | ast_i[i][2]=ast_i[i][2]-chi_ij[j][2]; |
---|
| 1690 | } |
---|
| 1691 | } |
---|
| 1692 | for(j=1;j<=size(ast_ijk);j++) |
---|
| 1693 | { |
---|
| 1694 | if((ast_ijk[j][1][1]==i)||(ast_ijk[j][1][2]==i) |
---|
| 1695 | ||(ast_ijk[j][1][3]==i)) |
---|
| 1696 | { |
---|
| 1697 | ast_i[i][2]=ast_i[i][2]+chi_ijk[j][2]; |
---|
| 1698 | } |
---|
| 1699 | } |
---|
| 1700 | } |
---|
| 1701 | for(i=size(idenE)+1;i<=size(iden);i++) |
---|
| 1702 | { |
---|
| 1703 | ast_i[i]=list(intvec(i),0); |
---|
| 1704 | } |
---|
| 1705 | //--- results are in ast_i, ast_ij and ast_ijk |
---|
| 1706 | //--- all are of the form intvec(indices),int(value) |
---|
| 1707 | //"End of chi_ast_local"; |
---|
| 1708 | //~; |
---|
| 1709 | list result=ast_i,ast_ij,ast_ijk; |
---|
| 1710 | return(result); |
---|
| 1711 | } |
---|
| 1712 | ////////////////////////////////////////////////////////////////////////////// |
---|
| 1713 | |
---|
[f4c2ba] | 1714 | proc discrepancy(list re) |
---|
| 1715 | "USAGE: discrepancy(L); |
---|
| 1716 | @* L = list of rings |
---|
| 1717 | ASSUME: L is the output of resolution of singularities |
---|
| 1718 | RETRUN: discrepancies of the given resolution" |
---|
| 1719 | { |
---|
| 1720 | //---------------------------------------------------------------------------- |
---|
| 1721 | // Initialization |
---|
| 1722 | //---------------------------------------------------------------------------- |
---|
| 1723 | def R=basering; |
---|
| 1724 | int i,j; |
---|
| 1725 | list iden=prepEmbDiv(re); //--- identify the E_i |
---|
| 1726 | intvec Vvec=computeV(re,iden); //--- nu |
---|
| 1727 | intvec Nvec=computeN(re,iden); //--- N |
---|
| 1728 | intvec Avec; |
---|
| 1729 | //--- only look at exceptional divisors, not at strict transform |
---|
| 1730 | for(i=1;i<=size(iden);i++) |
---|
| 1731 | { |
---|
| 1732 | if(defined(S)) {kill S;} |
---|
| 1733 | def S=re[2][iden[i][1][1]]; |
---|
| 1734 | setring S; |
---|
| 1735 | if(iden[i][1][2]>size(BO[4])) |
---|
| 1736 | { |
---|
| 1737 | i--; |
---|
| 1738 | break; |
---|
| 1739 | } |
---|
| 1740 | } |
---|
| 1741 | j=i; |
---|
| 1742 | //--- discrepancies are a_i=nu_i-N_i |
---|
| 1743 | for(i=1;i<=j;i++) |
---|
| 1744 | { |
---|
| 1745 | Avec[i]=Vvec[i]-Nvec[i]-1; |
---|
| 1746 | } |
---|
| 1747 | return(Avec); |
---|
| 1748 | } |
---|
| 1749 | example |
---|
| 1750 | {"EXAMPLE:"; |
---|
| 1751 | echo = 2; |
---|
| 1752 | ring R=0,(x,y,z),dp; |
---|
| 1753 | ideal I=x2+y2+z3; |
---|
| 1754 | list re=resolve(I); |
---|
| 1755 | discrepancy(re); |
---|
| 1756 | } |
---|
| 1757 | ////////////////////////////////////////////////////////////////////////////// |
---|
| 1758 | |
---|
[2e6eac2] | 1759 | proc zetaDL(list re,int d,list #) |
---|
[f4c2ba] | 1760 | "USAGE: zetaDL(L,d[,s1][,s2][,a]); |
---|
[471d0cf] | 1761 | L = list of rings; |
---|
| 1762 | d = integer; |
---|
| 1763 | s1,s2 = string; |
---|
| 1764 | a = integer |
---|
[2e6eac2] | 1765 | ASSUME: L is the output of resolution of singularities |
---|
[f4c2ba] | 1766 | COMPUTE: local Denef-Loeser zeta function, if string s1 is present and |
---|
[731e67e] | 1767 | has the value 'local'; global Denef-Loeser zeta function |
---|
[f4c2ba] | 1768 | otherwise |
---|
[731e67e] | 1769 | if string s1 or s2 has the value "A", additionally the |
---|
[f4c2ba] | 1770 | characteristic polynomial of the monodromy is computed |
---|
| 1771 | RETURN: list l |
---|
| 1772 | if a is not present: |
---|
[471d0cf] | 1773 | l[1]: string specifying the top. zeta function |
---|
[f4c2ba] | 1774 | l[2]: string specifying characteristic polynomial of monodromy, |
---|
| 1775 | if "A" was specified |
---|
[471d0cf] | 1776 | if a is present: |
---|
| 1777 | l[1]: string specifying the top. zeta function |
---|
[2e6eac2] | 1778 | l[2]: list ast, |
---|
| 1779 | ast[1]=chi(Ei^*) |
---|
| 1780 | ast[2]=chi(Eij^*) |
---|
| 1781 | ast[3]=chi(Eijk^*) |
---|
| 1782 | l[3]: intvec nu of multiplicites as needed in computation of zeta |
---|
| 1783 | function |
---|
| 1784 | l[4]: intvec N of multiplicities as needed in compuation of zeta |
---|
| 1785 | function |
---|
[f4c2ba] | 1786 | l[5]: string specifying characteristic polynomial of monodromy, |
---|
| 1787 | if "A" was specified |
---|
[2e6eac2] | 1788 | EXAMPLE: example zetaDL; shows an example |
---|
| 1789 | " |
---|
| 1790 | { |
---|
| 1791 | //---------------------------------------------------------------------------- |
---|
| 1792 | // Initialization |
---|
| 1793 | //---------------------------------------------------------------------------- |
---|
| 1794 | def R=basering; |
---|
| 1795 | int show_all,i; |
---|
| 1796 | if(size(#)>0) |
---|
| 1797 | { |
---|
[f4c2ba] | 1798 | if((typeof(#[1])=="int")||(size(#)>2)) |
---|
[2e6eac2] | 1799 | { |
---|
| 1800 | show_all=1; |
---|
| 1801 | } |
---|
| 1802 | if(typeof(#[1])=="string") |
---|
| 1803 | { |
---|
| 1804 | if((#[1]=="local")||(#[1]=="lokal")) |
---|
| 1805 | { |
---|
| 1806 | // ERROR("Local case not implemented yet"); |
---|
| 1807 | "Local Case: Assuming that no (!) charts were dropped"; |
---|
| 1808 | "during calculation of the resolution (option \"A\")"; |
---|
| 1809 | int localComp=1; |
---|
[f4c2ba] | 1810 | if(size(#)>1) |
---|
| 1811 | { |
---|
| 1812 | if(#[2]=="A") |
---|
| 1813 | { |
---|
| 1814 | int aCampoFormula=1; |
---|
| 1815 | } |
---|
| 1816 | } |
---|
[2e6eac2] | 1817 | } |
---|
| 1818 | else |
---|
| 1819 | { |
---|
[f4c2ba] | 1820 | if(#[1]=="A") |
---|
| 1821 | { |
---|
| 1822 | int aCampoFormula=1; |
---|
| 1823 | } |
---|
[2e6eac2] | 1824 | "Computing global zeta function"; |
---|
| 1825 | } |
---|
| 1826 | } |
---|
| 1827 | } |
---|
| 1828 | //---------------------------------------------------------------------------- |
---|
| 1829 | // Identify the embedded divisors and chi(Ei^*), chi(Eij^*) and chi(Eijk^*) |
---|
| 1830 | // as well as the integer vector V(=nu) and N |
---|
| 1831 | //---------------------------------------------------------------------------- |
---|
| 1832 | list iden=prepEmbDiv(re); //--- identify the E_i |
---|
| 1833 | //!!! TIMING: E8 takes 520 sec ==> needs speed up |
---|
| 1834 | if(!defined(localComp)) |
---|
| 1835 | { |
---|
| 1836 | list ast_list=chi_ast(re,iden); //--- compute chi(E^*) |
---|
| 1837 | } |
---|
| 1838 | else |
---|
| 1839 | { |
---|
| 1840 | list ast_list=chi_ast_local(re,iden); |
---|
| 1841 | } |
---|
| 1842 | intvec Vvec=computeV(re,iden); //--- nu |
---|
| 1843 | intvec Nvec=computeN(re,iden); //--- N |
---|
| 1844 | //---------------------------------------------------------------------------- |
---|
| 1845 | // Build a new ring with one parameter s |
---|
| 1846 | // and compute Zeta_top^(d) in its ground field |
---|
| 1847 | //---------------------------------------------------------------------------- |
---|
| 1848 | ring Qs=(0,s),x,dp; |
---|
| 1849 | number zetaTop=0; |
---|
| 1850 | number enum,denom; |
---|
| 1851 | denom=1; |
---|
| 1852 | for(i=1;i<=size(Nvec);i++) |
---|
| 1853 | { |
---|
| 1854 | denom=denom*(Vvec[i]+s*Nvec[i]); |
---|
| 1855 | } |
---|
| 1856 | //--- factors for which index set J consists of one element |
---|
| 1857 | //--- (do something only if d divides N_j) |
---|
| 1858 | for(i=1;i<=size(ast_list[1]);i++) |
---|
| 1859 | { |
---|
[1f9a84] | 1860 | if((((Nvec[ast_list[1][i][1][1]] div d)*d)-Nvec[ast_list[1][i][1][1]]==0)&& |
---|
[2e6eac2] | 1861 | (ast_list[1][i][2]!=0)) |
---|
| 1862 | { |
---|
| 1863 | enum=enum+ast_list[1][i][2]*(denom/(Vvec[ast_list[1][i][1][1]]+s*Nvec[ast_list[1][i][1][1]])); |
---|
| 1864 | } |
---|
| 1865 | } |
---|
| 1866 | //--- factors for which index set J consists of two elements |
---|
| 1867 | //--- (do something only if d divides both N_i and N_j) |
---|
| 1868 | //!!! TIMING: E8 takes 690 sec and has 703 elements |
---|
| 1869 | //!!! ==> need to implement a smarter way to do this |
---|
| 1870 | //!!! e.g. build up enumerator and denominator separately, thus not |
---|
| 1871 | //!!! searching for common factors in each step |
---|
| 1872 | for(i=1;i<=size(ast_list[2]);i++) |
---|
| 1873 | { |
---|
[1f9a84] | 1874 | if((((Nvec[ast_list[2][i][1][1]] div d)*d)-Nvec[ast_list[2][i][1][1]]==0)&& |
---|
| 1875 | (((Nvec[ast_list[2][i][1][2]] div d)*d)-Nvec[ast_list[2][i][1][2]]==0)&& |
---|
[2e6eac2] | 1876 | (ast_list[2][i][2]!=0)) |
---|
| 1877 | { |
---|
| 1878 | enum=enum+ast_list[2][i][2]*(denom/((Vvec[ast_list[2][i][1][1]]+s*Nvec[ast_list[2][i][1][1]])*(Vvec[ast_list[2][i][1][2]]+s*Nvec[ast_list[2][i][1][2]]))); |
---|
| 1879 | } |
---|
| 1880 | } |
---|
| 1881 | //--- factors for which index set J consists of three elements |
---|
| 1882 | //--- (do something only if d divides N_i, N_j and N_k) |
---|
| 1883 | //!!! TIMING: E8 takes 490 sec and has 8436 elements |
---|
| 1884 | //!!! ==> same kind of improvements as in the previous case needed |
---|
| 1885 | for(i=1;i<=size(ast_list[3]);i++) |
---|
| 1886 | { |
---|
[1f9a84] | 1887 | if((((Nvec[ast_list[3][i][1][1]] div d)*d)-Nvec[ast_list[3][i][1][1]]==0)&& |
---|
| 1888 | (((Nvec[ast_list[3][i][1][2]] div d)*d)-Nvec[ast_list[3][i][1][2]]==0)&& |
---|
| 1889 | (((Nvec[ast_list[3][i][1][3]] div d)*d)-Nvec[ast_list[3][i][1][3]]==0)&& |
---|
[2e6eac2] | 1890 | (ast_list[3][i][2]!=0)) |
---|
| 1891 | { |
---|
| 1892 | enum=enum+ast_list[3][i][2]*(denom/((Vvec[ast_list[3][i][1][1]]+s*Nvec[ast_list[3][i][1][1]])*(Vvec[ast_list[3][i][1][2]]+s*Nvec[ast_list[3][i][1][2]])*(Vvec[ast_list[3][i][1][3]]+s*Nvec[ast_list[3][i][1][3]]))); |
---|
| 1893 | } |
---|
| 1894 | } |
---|
| 1895 | zetaTop=enum/denom; |
---|
| 1896 | zetaTop=numerator(zetaTop)/denominator(zetaTop); |
---|
| 1897 | string zetaStr=string(zetaTop); |
---|
| 1898 | |
---|
| 1899 | if(show_all) |
---|
| 1900 | { |
---|
[f4c2ba] | 1901 | list result=zetaStr,ast_list[1],ast_list[2],ast_list[3],Vvec,Nvec; |
---|
[2e6eac2] | 1902 | } |
---|
| 1903 | else |
---|
| 1904 | { |
---|
| 1905 | list result=zetaStr; |
---|
| 1906 | } |
---|
[f4c2ba] | 1907 | //--- compute characteristic polynomial of the monodromy |
---|
| 1908 | //--- by the A'Campo formula |
---|
| 1909 | if(defined(aCampoFormula)) |
---|
| 1910 | { |
---|
| 1911 | poly charP=1; |
---|
| 1912 | for(i=1;i<=size(ast_list[1]);i++) |
---|
| 1913 | { |
---|
| 1914 | charP=charP*((s^Nvec[i]-1)^ast_list[1][i][2]); |
---|
| 1915 | } |
---|
| 1916 | string charPStr=string(charP/(s-1)); |
---|
| 1917 | result[size(result)+1]=charPStr; |
---|
| 1918 | } |
---|
[2e6eac2] | 1919 | setring R; |
---|
| 1920 | return(result); |
---|
| 1921 | } |
---|
| 1922 | example |
---|
| 1923 | {"EXAMPLE:"; |
---|
| 1924 | echo = 2; |
---|
| 1925 | ring R=0,(x,y,z),dp; |
---|
| 1926 | ideal I=x2+y2+z3; |
---|
| 1927 | list re=resolve(I,"K"); |
---|
| 1928 | zetaDL(re,1); |
---|
| 1929 | I=(xz+y2)*(xz+y2+x2)+z5; |
---|
| 1930 | list L=resolve(I,"K"); |
---|
| 1931 | zetaDL(L,1); |
---|
| 1932 | |
---|
| 1933 | //===== expected zeta function ========= |
---|
[29bc73] | 1934 | // (20s^2+130s+87)/((1+s)*(3+4s)*(29+40s)) |
---|
[2e6eac2] | 1935 | //====================================== |
---|
| 1936 | } |
---|
| 1937 | ////////////////////////////////////////////////////////////////////////////// |
---|
| 1938 | |
---|
| 1939 | proc abstractR(list re) |
---|
| 1940 | "USAGE: abstractR(L); |
---|
| 1941 | @* L = list of rings |
---|
| 1942 | ASSUME: L is output of resolution of singularities |
---|
| 1943 | NOTE: currently only implemented for isolated surface singularities |
---|
| 1944 | RETURN: list l |
---|
| 1945 | l[1]: intvec, where |
---|
| 1946 | l[1][i]=1 if the corresponding ring is a final chart |
---|
| 1947 | of non-embedded resolution |
---|
| 1948 | l[1][i]=0 otherwise |
---|
| 1949 | l[2]: intvec, where |
---|
| 1950 | l[2][i]=1 if the corresponding ring does not occur |
---|
| 1951 | in the non-embedded resolution |
---|
| 1952 | l[2][i]=0 otherwise |
---|
| 1953 | l[3]: list L |
---|
| 1954 | EXAMPLE: example abstractR; shows an example |
---|
| 1955 | " |
---|
| 1956 | { |
---|
| 1957 | //--------------------------------------------------------------------------- |
---|
| 1958 | // Initialization and sanity checks |
---|
| 1959 | //--------------------------------------------------------------------------- |
---|
| 1960 | def R=basering; |
---|
| 1961 | //---Test whether we are in the irreducible surface case |
---|
| 1962 | def S=re[2][1]; |
---|
| 1963 | setring S; |
---|
| 1964 | BO[2]=BO[2]+BO[1]; |
---|
| 1965 | if(dim(std(BO[2]))!=2) |
---|
| 1966 | { |
---|
| 1967 | ERROR("NOT A SURFACE"); |
---|
| 1968 | } |
---|
| 1969 | if(dim(std(slocus(BO[2])))>0) |
---|
| 1970 | { |
---|
| 1971 | ERROR("NOT AN ISOLATED SINGULARITY"); |
---|
| 1972 | } |
---|
| 1973 | setring R; |
---|
| 1974 | int i,j,k,l,i0; |
---|
| 1975 | intvec deleted; |
---|
| 1976 | intvec endiv; |
---|
| 1977 | endiv[size(re[2])]=0; |
---|
| 1978 | deleted[size(re[2])]=0; |
---|
| 1979 | //----------------------------------------------------------------------------- |
---|
| 1980 | // run through all rings, only consider final charts |
---|
| 1981 | // for each final chart follow the list of charts leading up to it until |
---|
| 1982 | // we encounter a chart which is not finished in the non-embedded case |
---|
| 1983 | //----------------------------------------------------------------------------- |
---|
| 1984 | for(i=1;i<=size(re[2]);i++) |
---|
| 1985 | { |
---|
| 1986 | if(defined(S)){kill S;} |
---|
| 1987 | def S=re[2][i]; |
---|
| 1988 | setring S; |
---|
| 1989 | if(size(reduce(cent,std(BO[2]+BO[1])))!=0) |
---|
| 1990 | { |
---|
| 1991 | //--- only consider endrings |
---|
| 1992 | i++; |
---|
| 1993 | continue; |
---|
| 1994 | } |
---|
| 1995 | i0=i; |
---|
| 1996 | for(j=ncols(path);j>=2;j--) |
---|
| 1997 | { |
---|
| 1998 | //--- walk backwards through history |
---|
| 1999 | if(j==2) |
---|
| 2000 | { |
---|
| 2001 | endiv[i0]=1; |
---|
| 2002 | break; |
---|
| 2003 | } |
---|
| 2004 | k=int(leadcoef(path[1,j])); |
---|
| 2005 | if((deleted[k]==1)||(endiv[k]==1)) |
---|
| 2006 | { |
---|
| 2007 | deleted[i0]=1; |
---|
| 2008 | break; |
---|
| 2009 | } |
---|
| 2010 | if(defined(SPa)){kill SPa;} |
---|
| 2011 | def SPa=re[2][k]; |
---|
| 2012 | setring SPa; |
---|
| 2013 | l=int(leadcoef(path[1,ncols(path)])); |
---|
| 2014 | if(defined(SPa2)){kill SPa2;} |
---|
| 2015 | def SPa2=re[2][l]; |
---|
| 2016 | setring SPa2; |
---|
| 2017 | if((deleted[l]==1)||(endiv[l]==1)) |
---|
| 2018 | { |
---|
| 2019 | //--- parent was already treated via different final chart |
---|
| 2020 | //--- we may safely inherit the data |
---|
| 2021 | deleted[i0]=1; |
---|
| 2022 | setring S; |
---|
| 2023 | i0=k; |
---|
| 2024 | j--; |
---|
| 2025 | continue; |
---|
| 2026 | } |
---|
| 2027 | setring SPa; |
---|
| 2028 | //!!! Idea of Improvement: |
---|
| 2029 | //!!! BESSER: rueckwaerts gehend nur testen ob glatt |
---|
| 2030 | //!!! danach vorwaerts bis zum ersten Mal abstractNC |
---|
| 2031 | //!!! ACHTUNG: rueckweg unterwegs notieren - wir haben nur vergangenheit! |
---|
| 2032 | if((deg(std(slocus(BO[2]))[1])!=0)||(!abstractNC(BO))) |
---|
| 2033 | { |
---|
| 2034 | //--- not finished in the non-embedded case |
---|
| 2035 | endiv[i0]=1; |
---|
| 2036 | break; |
---|
| 2037 | } |
---|
| 2038 | //--- unnecessary chart in non-embedded case |
---|
| 2039 | setring S; |
---|
| 2040 | deleted[i0]=1; |
---|
| 2041 | i0=k; |
---|
| 2042 | } |
---|
| 2043 | } |
---|
| 2044 | //----------------------------------------------------------------------------- |
---|
| 2045 | // Clean up the intvec deleted and return the result |
---|
| 2046 | //----------------------------------------------------------------------------- |
---|
| 2047 | setring R; |
---|
| 2048 | for(i=1;i<=size(endiv);i++) |
---|
| 2049 | { |
---|
| 2050 | if(endiv[i]==1) |
---|
| 2051 | { |
---|
| 2052 | if(defined(S)) {kill S;} |
---|
| 2053 | def S=re[2][i]; |
---|
| 2054 | setring S; |
---|
| 2055 | for(j=3;j<ncols(path);j++) |
---|
| 2056 | { |
---|
| 2057 | if((endiv[int(leadcoef(path[1,j]))]==1)|| |
---|
| 2058 | (deleted[int(leadcoef(path[1,j]))]==1)) |
---|
| 2059 | { |
---|
| 2060 | deleted[int(leadcoef(path[1,j+1]))]=1; |
---|
| 2061 | endiv[int(leadcoef(path[1,j+1]))]=0; |
---|
| 2062 | } |
---|
| 2063 | } |
---|
| 2064 | if((endiv[int(leadcoef(path[1,ncols(path)]))]==1)|| |
---|
| 2065 | (deleted[int(leadcoef(path[1,ncols(path)]))]==1)) |
---|
| 2066 | { |
---|
| 2067 | deleted[i]=1; |
---|
| 2068 | endiv[i]=0; |
---|
| 2069 | } |
---|
| 2070 | } |
---|
| 2071 | } |
---|
| 2072 | list resu=endiv,deleted,re; |
---|
| 2073 | return(resu); |
---|
| 2074 | } |
---|
| 2075 | example |
---|
| 2076 | {"EXAMPLE:"; |
---|
| 2077 | echo = 2; |
---|
| 2078 | ring r = 0,(x,y,z),dp; |
---|
| 2079 | ideal I=x2+y2+z11; |
---|
| 2080 | list L=resolve(I); |
---|
[471d0cf] | 2081 | list absR=abstractR(L); |
---|
| 2082 | absR[1]; |
---|
| 2083 | absR[2]; |
---|
[2e6eac2] | 2084 | } |
---|
| 2085 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 2086 | static proc decompE(list BO) |
---|
[2e6eac2] | 2087 | "Internal procedure - no help and no example available |
---|
| 2088 | " |
---|
| 2089 | { |
---|
| 2090 | //--- compute the list of exceptional divisors, including the components |
---|
| 2091 | //--- of the strict transform in the non-embedded case |
---|
| 2092 | //--- (computation over Q !!!) |
---|
| 2093 | def R=basering; |
---|
| 2094 | list Elist,prList; |
---|
| 2095 | int i; |
---|
| 2096 | for(i=1;i<=size(BO[4]);i++) |
---|
| 2097 | { |
---|
| 2098 | Elist[i]=BO[4][i]; |
---|
| 2099 | } |
---|
| 2100 | /* practical speed up (part 1 of 3) -- no theoretical relevance |
---|
| 2101 | ideal M=maxideal(1); |
---|
| 2102 | M[1]=var(nvars(basering)); |
---|
| 2103 | M[nvars(basering)]=var(1); |
---|
| 2104 | map phi=R,M; |
---|
| 2105 | */ |
---|
| 2106 | ideal KK=BO[2]; |
---|
| 2107 | |
---|
| 2108 | /* practical speed up (part 2 of 3) |
---|
| 2109 | KK=phi(KK); |
---|
| 2110 | */ |
---|
| 2111 | prList=minAssGTZ(KK); |
---|
| 2112 | |
---|
| 2113 | /* practical speed up (part 3 of 3) |
---|
| 2114 | prList=phi(prList); |
---|
| 2115 | */ |
---|
| 2116 | |
---|
| 2117 | for(i=1;i<=size(prList);i++) |
---|
| 2118 | { |
---|
| 2119 | Elist[size(BO[4])+i]=prList[i]; |
---|
| 2120 | } |
---|
| 2121 | return(Elist); |
---|
| 2122 | } |
---|
| 2123 | ////////////////////////////////////////////////////////////////////////////// |
---|
| 2124 | |
---|
| 2125 | proc prepEmbDiv(list re, list #) |
---|
| 2126 | "USAGE: prepEmbDiv(L[,a]); |
---|
| 2127 | @* L = list of rings |
---|
| 2128 | @* a = integer |
---|
| 2129 | ASSUME: L is output of resolution of singularities |
---|
| 2130 | COMPUTE: if a is not present: exceptional divisors including components |
---|
| 2131 | of the strict transform |
---|
| 2132 | otherwise: only exceptional divisors |
---|
| 2133 | RETURN: list of Q-irreducible exceptional divisors (embedded case) |
---|
| 2134 | EXAMPLE: example prepEmbDiv; shows an example |
---|
| 2135 | " |
---|
| 2136 | { |
---|
| 2137 | //--- 1) in each final chart, a list of (decomposed) exceptional divisors |
---|
| 2138 | //--- is created (and exported) |
---|
| 2139 | //--- 2) the strict transform is decomposed |
---|
| 2140 | //--- 3) the exceptional divisors (including the strict transform) |
---|
| 2141 | //--- in the different charts are compared, identified and this |
---|
| 2142 | //--- information collected into a list which is then returned |
---|
| 2143 | //--------------------------------------------------------------------------- |
---|
| 2144 | // Initialization |
---|
| 2145 | //--------------------------------------------------------------------------- |
---|
| 2146 | int i,j,k,ncomps,offset,found,a,b,c,d; |
---|
| 2147 | list tmpList; |
---|
| 2148 | def R=basering; |
---|
| 2149 | //--- identify identical exceptional divisors |
---|
| 2150 | //--- (note: we are in the embedded case) |
---|
| 2151 | list iden=collectDiv(re)[2]; |
---|
| 2152 | //--------------------------------------------------------------------------- |
---|
| 2153 | // Go to each final chart and create the EList |
---|
| 2154 | //--------------------------------------------------------------------------- |
---|
| 2155 | for(i=1;i<=size(iden[size(iden)]);i++) |
---|
| 2156 | { |
---|
| 2157 | if(defined(S)){kill S;} |
---|
| 2158 | def S=re[2][iden[size(iden)][i][1]]; |
---|
| 2159 | setring S; |
---|
| 2160 | if(defined(EList)){kill EList;} |
---|
| 2161 | list EList=decompE(BO); |
---|
| 2162 | export(EList); |
---|
| 2163 | setring R; |
---|
| 2164 | kill S; |
---|
| 2165 | } |
---|
| 2166 | //--- save original iden for further use and then drop |
---|
| 2167 | //--- strict transform from it |
---|
| 2168 | list iden0=iden; |
---|
| 2169 | iden=delete(iden,size(iden)); |
---|
| 2170 | if(size(#)>0) |
---|
| 2171 | { |
---|
| 2172 | //--- we are not interested in the strict transform of X |
---|
| 2173 | return(iden); |
---|
| 2174 | } |
---|
| 2175 | //---------------------------------------------------------------------------- |
---|
| 2176 | // Run through all final charts and collect and identify all components of |
---|
| 2177 | // the strict transform |
---|
| 2178 | //---------------------------------------------------------------------------- |
---|
| 2179 | //--- first final chart - to be used for initialization |
---|
| 2180 | def S=re[2][iden0[size(iden0)][1][1]]; |
---|
| 2181 | setring S; |
---|
| 2182 | ncomps=size(EList)-size(BO[4]); |
---|
| 2183 | if((ncomps==1)&&(deg(std(EList[size(EList)])[1])==0)) |
---|
| 2184 | { |
---|
| 2185 | ncomps=0; |
---|
| 2186 | } |
---|
| 2187 | offset=size(BO[4]); |
---|
| 2188 | for(i=1;i<=ncomps;i++) |
---|
| 2189 | { |
---|
| 2190 | //--- add components of strict transform |
---|
| 2191 | tmpList[1]=intvec(iden0[size(iden0)][1][1],size(BO[4])+i); |
---|
| 2192 | iden[size(iden)+1]=tmpList; |
---|
| 2193 | } |
---|
| 2194 | //--- now run through the other final charts |
---|
| 2195 | for(i=2;i<=size(iden0[size(iden0)]);i++) |
---|
| 2196 | { |
---|
| 2197 | if(defined(S2)){kill S2;} |
---|
| 2198 | def S2=re[2][iden0[size(iden0)][i][1]]; |
---|
| 2199 | setring S2; |
---|
| 2200 | //--- determine common parent of this ring and re[2][iden0[size(iden0)][1][1]] |
---|
| 2201 | if(defined(opath)){kill opath;} |
---|
| 2202 | def opath=imap(S,path); |
---|
| 2203 | j=1; |
---|
| 2204 | while(opath[1,j]==path[1,j]) |
---|
| 2205 | { |
---|
| 2206 | j++; |
---|
| 2207 | if((j>ncols(path))||(j>ncols(opath))) break; |
---|
| 2208 | } |
---|
| 2209 | if(defined(li1)){kill li1;} |
---|
| 2210 | list li1; |
---|
| 2211 | //--- fetch the components we have considered in |
---|
| 2212 | //--- re[2][iden0[size(iden0)][1][1]] |
---|
| 2213 | //--- via the resolution tree |
---|
| 2214 | for(k=1;k<=ncomps;k++) |
---|
| 2215 | { |
---|
| 2216 | if(defined(id1)){kill id1;} |
---|
| 2217 | string tempstr="EList["+string(eval(k+offset))+"]"; |
---|
| 2218 | ideal id1=fetchInTree(re,iden0[size(iden0)][1][1], |
---|
| 2219 | int(leadcoef(path[1,j-1])), |
---|
| 2220 | iden0[size(iden0)][i][1],tempstr,iden0,1); |
---|
| 2221 | kill tempstr; |
---|
| 2222 | li1[k]=id1; |
---|
| 2223 | kill id1; |
---|
| 2224 | } |
---|
| 2225 | //--- do the comparison |
---|
| 2226 | for(k=size(BO[4])+1;k<=size(EList);k++) |
---|
| 2227 | { |
---|
| 2228 | //--- only components of the strict transform are interesting |
---|
| 2229 | if((size(BO[4])+1==size(EList))&&(deg(std(EList[size(EList)])[1])==0)) |
---|
| 2230 | { |
---|
| 2231 | break; |
---|
| 2232 | } |
---|
| 2233 | found=0; |
---|
| 2234 | for(j=1;j<=size(li1);j++) |
---|
| 2235 | { |
---|
| 2236 | if((size(reduce(li1[j],std(EList[k])))==0)&& |
---|
| 2237 | (size(reduce(EList[k],std(li1[j])))==0)) |
---|
| 2238 | { |
---|
| 2239 | //--- found a match |
---|
| 2240 | li1[j]=ideal(1); |
---|
| 2241 | iden[size(iden0)-1+j][size(iden[size(iden0)-1+j])+1]= |
---|
| 2242 | intvec(iden0[size(iden0)][i][1],k); |
---|
| 2243 | found=1; |
---|
| 2244 | break; |
---|
| 2245 | } |
---|
| 2246 | } |
---|
| 2247 | if(!found) |
---|
| 2248 | { |
---|
| 2249 | //--- no match yet, maybe there are entries not corresponding to the |
---|
| 2250 | //--- initialization of the list -- collected in list repair |
---|
| 2251 | if(!defined(repair)) |
---|
| 2252 | { |
---|
| 2253 | //--- no entries in repair, we add the very first one |
---|
| 2254 | list repair; |
---|
| 2255 | repair[1]=list(intvec(iden0[size(iden0)][i][1],k)); |
---|
| 2256 | } |
---|
| 2257 | else |
---|
| 2258 | { |
---|
| 2259 | //--- compare against repair, and add the item appropriately |
---|
| 2260 | //--- steps of comparison as before |
---|
| 2261 | for(c=1;c<=size(repair);c++) |
---|
| 2262 | { |
---|
| 2263 | for(d=1;d<=size(repair[c]);d++) |
---|
| 2264 | { |
---|
| 2265 | if(defined(opath)) {kill opath;} |
---|
| 2266 | def opath=imap(re[2][repair[c][d][1]],path); |
---|
| 2267 | b=0; |
---|
| 2268 | while(path[1,b+1]==opath[1,b+1]) |
---|
| 2269 | { |
---|
| 2270 | b++; |
---|
| 2271 | if((b>ncols(path)-1)||(b>ncols(opath)-1)) break; |
---|
| 2272 | } |
---|
| 2273 | b=int(leadcoef(path[1,b])); |
---|
| 2274 | string tempstr="EList["+string(eval(repair[c][d][2])) |
---|
| 2275 | +"]"; |
---|
| 2276 | if(defined(id1)){kill id1;} |
---|
| 2277 | ideal id1=fetchInTree(re,repair[c][d][1],b, |
---|
| 2278 | iden0[size(iden0)][i][1],tempstr,iden0,1); |
---|
| 2279 | kill tempstr; |
---|
| 2280 | if((size(reduce(EList[k],std(id1)))==0)&& |
---|
| 2281 | (size(reduce(id1,std(EList[k])))==0)) |
---|
| 2282 | { |
---|
| 2283 | repair[c][size(repair[c])+1]=intvec(iden0[size(iden0)][i][1],k); |
---|
| 2284 | break; |
---|
| 2285 | } |
---|
| 2286 | } |
---|
| 2287 | if(d<=size(repair[c])) |
---|
| 2288 | { |
---|
| 2289 | break; |
---|
| 2290 | } |
---|
| 2291 | } |
---|
| 2292 | if(c>size(repair)) |
---|
| 2293 | { |
---|
| 2294 | repair[size(repair)+1]=list(intvec(iden0[size(iden0)][i][1],k)); |
---|
| 2295 | } |
---|
| 2296 | } |
---|
| 2297 | } |
---|
| 2298 | } |
---|
| 2299 | } |
---|
| 2300 | if(defined(repair)) |
---|
| 2301 | { |
---|
| 2302 | //--- there were further components, add them |
---|
| 2303 | for(c=1;c<=size(repair);c++) |
---|
| 2304 | { |
---|
| 2305 | iden[size(iden)+1]=repair[c]; |
---|
| 2306 | } |
---|
| 2307 | kill repair; |
---|
| 2308 | } |
---|
| 2309 | //--- up to now only Q-irred components - not C-irred components !!! |
---|
| 2310 | return(iden); |
---|
| 2311 | } |
---|
| 2312 | example |
---|
| 2313 | {"EXAMPLE:"; |
---|
| 2314 | echo = 2; |
---|
| 2315 | ring R=0,(x,y,z),dp; |
---|
| 2316 | ideal I=x2+y2+z11; |
---|
| 2317 | list L=resolve(I); |
---|
| 2318 | prepEmbDiv(L); |
---|
| 2319 | } |
---|
| 2320 | /////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 2321 | static proc decompEinX(list BO) |
---|
[2e6eac2] | 2322 | "Internal procedure - no help and no example available |
---|
| 2323 | " |
---|
| 2324 | { |
---|
| 2325 | //--- decomposition of exceptional divisor, non-embedded resolution. |
---|
| 2326 | //--- even a single exceptional divisor may be Q-reducible when considered |
---|
| 2327 | //--- as divisor on the strict transform |
---|
| 2328 | |
---|
| 2329 | //---------------------------------------------------------------------------- |
---|
| 2330 | // Initialization |
---|
| 2331 | //---------------------------------------------------------------------------- |
---|
| 2332 | int i,j,k,de,contact; |
---|
| 2333 | intmat interMat; |
---|
| 2334 | list dcE,tmpList,prList,sa,nullList; |
---|
| 2335 | string mpol,compList; |
---|
| 2336 | def R=basering; |
---|
| 2337 | ideal I; |
---|
| 2338 | //---------------------------------------------------------------------------- |
---|
| 2339 | // pass to divisors on V(J) and throw away components already present as |
---|
| 2340 | // previous exceptional divisors |
---|
| 2341 | //---------------------------------------------------------------------------- |
---|
| 2342 | for(i=1;i<=size(BO[4]);i++) |
---|
| 2343 | { |
---|
| 2344 | I=BO[4][i]+BO[2]; |
---|
| 2345 | for(j=i+1;j<=size(BO[4]);j++) |
---|
| 2346 | { |
---|
| 2347 | sa=sat(I,BO[4][j]+BO[2]); |
---|
| 2348 | if(sa[2]) |
---|
| 2349 | { |
---|
| 2350 | I=sa[1]; |
---|
| 2351 | } |
---|
| 2352 | } |
---|
| 2353 | //!!! Practical improvement - not yet implemented: |
---|
| 2354 | //!!!hier den Input besser aufbereiten (cf. J. Wahl's example) |
---|
| 2355 | //!!!I[1]=x(2)^15*y(2)^9+3*x(2)^10*y(2)^6+3*x(2)^5*y(2)^3+x(2)+1; |
---|
| 2356 | //!!!I[2]=x(2)^8*y(2)^6+y(0); |
---|
| 2357 | //!!!heuristisch die Ordnung so waehlen, dass y(0) im Prinzip eliminiert |
---|
| 2358 | //!!!wird. |
---|
| 2359 | //----------------------------------------------------------------------------- |
---|
| 2360 | // 1) decompose exceptional divisor (over Q) |
---|
| 2361 | // 2) check whether there are C-reducible Q-components |
---|
| 2362 | // 3) if necessary, find appropriate field extension of Q to decompose |
---|
| 2363 | // 4) in each chart collect information in list dcE and export it |
---|
| 2364 | //----------------------------------------------------------------------------- |
---|
| 2365 | prList=primdecGTZ(I); |
---|
| 2366 | for(j=1;j<=size(prList);j++) |
---|
| 2367 | { |
---|
| 2368 | tmpList=grad(prList[j][2]); |
---|
| 2369 | de=tmpList[1]; |
---|
| 2370 | interMat=tmpList[2]; |
---|
| 2371 | mpol=tmpList[3]; |
---|
| 2372 | compList=tmpList[4]; |
---|
| 2373 | nullList=tmpList[5]; |
---|
| 2374 | contact=Kontakt(prList[j][1],BO[2]); |
---|
| 2375 | tmpList=prList[j][2],de,contact,interMat,mpol,compList,nullList; |
---|
| 2376 | prList[j]=tmpList; |
---|
| 2377 | } |
---|
| 2378 | dcE[i]=prList; |
---|
| 2379 | } |
---|
| 2380 | return(dcE); |
---|
| 2381 | } |
---|
| 2382 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 2383 | static proc getMinpoly(poly p) |
---|
[2e6eac2] | 2384 | "Internal procedure - no help and no example available |
---|
| 2385 | " |
---|
| 2386 | { |
---|
| 2387 | //---assume that p is a polynomial in 2 variables and irreducible |
---|
| 2388 | //---over Q. Computes an irreducible polynomial mp in one variable |
---|
| 2389 | //---over Q such that p splits completely over the splitting field of mp |
---|
| 2390 | //---returns mp as a string |
---|
| 2391 | //---use a variant of the algorithm of S. Gao |
---|
| 2392 | def R=basering; |
---|
| 2393 | int i,j,k,a,b,m,n; |
---|
| 2394 | intvec v; |
---|
| 2395 | string mp="poly p=t-1;"; |
---|
| 2396 | list Li=string(1); |
---|
| 2397 | list re=mp,Li,1; |
---|
| 2398 | |
---|
| 2399 | //---check which variables occur in p |
---|
| 2400 | for(i=1;i<=nvars(basering);i++) |
---|
| 2401 | { |
---|
| 2402 | if(p!=subst(p,var(i),0)){v[size(v)+1]=i;} |
---|
| 2403 | } |
---|
| 2404 | |
---|
[3754ca] | 2405 | //---the polynomial is constant |
---|
[2e6eac2] | 2406 | if(size(v)==1){return(re);} |
---|
| 2407 | |
---|
[3754ca] | 2408 | //---the polynomial depends only on one variable or is homogeneous |
---|
[2e6eac2] | 2409 | //---in 2 variables |
---|
| 2410 | if((size(v)==2)||((size(v)==3)&&(homog(p)))) |
---|
| 2411 | { |
---|
| 2412 | if((size(v)==3)&&(homog(p))) |
---|
| 2413 | { |
---|
| 2414 | p=subst(p,var(v[3]),1); |
---|
| 2415 | } |
---|
| 2416 | ring Rhelp=0,var(v[2]),dp; |
---|
| 2417 | poly p=imap(R,p); |
---|
| 2418 | ring Shelp=0,t,dp; |
---|
| 2419 | poly p=fetch(Rhelp,p); |
---|
| 2420 | int de=deg(p); |
---|
| 2421 | p=simplifyMinpoly(p); |
---|
| 2422 | Li=getNumZeros(p); |
---|
| 2423 | short=0; |
---|
| 2424 | mp="poly p="+string(p)+";"; |
---|
| 2425 | re=mp,Li,de; |
---|
| 2426 | setring R; |
---|
| 2427 | return(re); |
---|
| 2428 | } |
---|
| 2429 | v=v[2..size(v)]; |
---|
| 2430 | if(size(v)>2){ERROR("getMinpoly:input depends on more then 2 variables");} |
---|
| 2431 | |
---|
[3754ca] | 2432 | //---the general case, the polynomial is considered as polynomial in x an y now |
---|
[2e6eac2] | 2433 | ring T=0,(x,y),lp; |
---|
| 2434 | ideal M,N; |
---|
| 2435 | M[nvars(R)]=0; |
---|
| 2436 | N[nvars(R)]=0; |
---|
| 2437 | M[v[1]]=x; |
---|
| 2438 | N[v[1]]=y; |
---|
| 2439 | M[v[2]]=y; |
---|
| 2440 | N[v[2]]=x; |
---|
| 2441 | map phi=R,M; |
---|
| 2442 | map psi=R,N; |
---|
| 2443 | poly p=phi(p); |
---|
| 2444 | poly q=psi(p); |
---|
| 2445 | ring Thelp=(0,x),y,dp; |
---|
| 2446 | poly p=imap(T,p); |
---|
| 2447 | poly q=imap(T,q); |
---|
| 2448 | n=deg(p); //---the degree with respect to y |
---|
| 2449 | m=deg(q); //---the degree with respect to x |
---|
| 2450 | setring T; |
---|
| 2451 | ring A=0,(u(1..m*(n+1)),v(1..(m+1)*n),x,y,t),dp; |
---|
| 2452 | poly f=imap(T,p); |
---|
| 2453 | poly g; |
---|
| 2454 | poly h; |
---|
| 2455 | for(i=0;i<=m-1;i++) |
---|
| 2456 | { |
---|
| 2457 | for(j=0;j<=n;j++) |
---|
| 2458 | { |
---|
| 2459 | g=g+u(i*(n+1)+j+1)*x^i*y^j; |
---|
| 2460 | } |
---|
| 2461 | } |
---|
| 2462 | for(i=0;i<=m;i++) |
---|
| 2463 | { |
---|
| 2464 | for(j=0;j<=n-1;j++) |
---|
| 2465 | { |
---|
| 2466 | h=h+v(i*n+j+1)*x^i*y^j; |
---|
| 2467 | } |
---|
| 2468 | } |
---|
| 2469 | poly L=f*(diff(g,y)-diff(h,x))+h*diff(f,x)-g*diff(f,y); |
---|
[3754ca] | 2470 | //---according to the theory f is absolutely irreducible if and only if |
---|
[2e6eac2] | 2471 | //---L(g,h)=0 has no non-trivial solution g,h |
---|
| 2472 | //---(g=diff(f,x),h=diff(f,y) is always a solution) |
---|
| 2473 | //---therefore we compute a vector space basis of G |
---|
| 2474 | //---G={g in Q[x,y],deg_x(g)<m,|exist h, such that L(g,h)=0} |
---|
| 2475 | //---dim(G)=a is the number of factors of f in C[x,y] |
---|
| 2476 | matrix M=coef(L,xy); |
---|
| 2477 | ideal J=M[2,1..ncols(M)]; |
---|
| 2478 | option(redSB); |
---|
| 2479 | J=std(J); |
---|
| 2480 | option(noredSB); |
---|
| 2481 | poly gred=reduce(g,J); |
---|
| 2482 | ideal G; |
---|
| 2483 | for(i=1;i<=m*(n+1);i++) |
---|
| 2484 | { |
---|
| 2485 | if(gred!=subst(gred,u(i),0)) |
---|
| 2486 | { |
---|
| 2487 | G[size(G)+1]=subst(gred,u(i),1); |
---|
| 2488 | } |
---|
| 2489 | } |
---|
| 2490 | for(i=1;i<=n*(m+1);i++) |
---|
| 2491 | { |
---|
| 2492 | if(gred!=subst(gred,v(i),0)) |
---|
| 2493 | { |
---|
| 2494 | G[size(G)+1]=subst(gred,v(i),1); |
---|
| 2495 | } |
---|
| 2496 | } |
---|
| 2497 | for(i=1;i<=m*(n+1);i++) |
---|
| 2498 | { |
---|
| 2499 | G=subst(G,u(i),0); |
---|
| 2500 | } |
---|
| 2501 | for(i=1;i<=n*(m+1);i++) |
---|
| 2502 | { |
---|
| 2503 | G=subst(G,v(i),0); |
---|
| 2504 | } |
---|
| 2505 | //---the number of factors in C[x,y] |
---|
| 2506 | a=size(G); |
---|
| 2507 | for(i=1;i<=a;i++) |
---|
| 2508 | { |
---|
| 2509 | G[i]=simplify(G[i],1); |
---|
| 2510 | } |
---|
| 2511 | if(a==1) |
---|
| 2512 | { |
---|
| 2513 | //---f is absolutely irreducible |
---|
| 2514 | setring R; |
---|
| 2515 | return(re); |
---|
| 2516 | } |
---|
| 2517 | //---let g in G be any non-trivial element (g not in <diff(f,x)>) |
---|
| 2518 | //---according to the theory f=product over all c in C of the |
---|
| 2519 | //---gcd(f,g-c*diff(f,x)) |
---|
| 2520 | //---let g_1,...,g_a be a basis of G and write |
---|
| 2521 | //---g*g_i=sum a_ij*g_j*diff(f,x) mod f |
---|
| 2522 | //---let B=(a_ij) and ch=det(t*unitmat(a)-B) the characteristic |
---|
| 2523 | //---polynomial then the number of distinct irreducible factors |
---|
| 2524 | //---of gcd(f,g-c*diff(f,x)) in C[x,y] is equal to the multiplicity |
---|
| 2525 | //---of c as a root of ch. |
---|
| 2526 | //---in our special situation (f is irreducible over Q) ch should |
---|
| 2527 | //---be irreducible and the different roots of ch lead to the |
---|
| 2528 | //---factors of f, i.e. ch is the minpoly we are looking for |
---|
| 2529 | |
---|
| 2530 | poly fh=homog(f,t); |
---|
| 2531 | //---homogenization is used to obtain a constant matrix using lift |
---|
| 2532 | ideal Gh=homog(G,t); |
---|
| 2533 | int dh,df; |
---|
| 2534 | df=deg(fh); |
---|
| 2535 | for(i=1;i<=a;i++) |
---|
| 2536 | { |
---|
| 2537 | if(deg(Gh[i])>dh){dh=deg(Gh[i]);} |
---|
| 2538 | } |
---|
| 2539 | for(i=1;i<=a;i++) |
---|
| 2540 | { |
---|
| 2541 | Gh[i]=t^(dh-deg(Gh[i]))*Gh[i]; |
---|
| 2542 | } |
---|
| 2543 | ideal GF=simplify(diff(fh,x),1)*Gh,fh; |
---|
| 2544 | poly ch; |
---|
| 2545 | matrix LI; |
---|
| 2546 | matrix B[a][a]; |
---|
| 2547 | matrix E=unitmat(a); |
---|
| 2548 | poly gran; |
---|
| 2549 | ideal fac; |
---|
| 2550 | for(i=1;i<=a;i++) |
---|
| 2551 | { |
---|
| 2552 | LI=lift(GF,t^(df-1-dh)*Gh[i]*Gh); |
---|
| 2553 | B=LI[1..a,1..a]; |
---|
| 2554 | ch=det(t*E-B); |
---|
| 2555 | //---irreducibility test |
---|
| 2556 | fac=factorize(ch,1); |
---|
| 2557 | if(deg(fac[1])==a) |
---|
| 2558 | { |
---|
| 2559 | ch=simplifyMinpoly(ch); |
---|
| 2560 | Li=getNumZeros(ch); |
---|
| 2561 | int de=deg(ch); |
---|
| 2562 | short=0; |
---|
| 2563 | mp="poly p="+string(ch)+";"; |
---|
| 2564 | re=mp,Li,de; |
---|
| 2565 | setring R; |
---|
| 2566 | return(re); |
---|
| 2567 | } |
---|
| 2568 | } |
---|
| 2569 | ERROR("getMinpoly:not found:please send the example to the authors"); |
---|
| 2570 | } |
---|
| 2571 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 2572 | static proc getNumZeros(poly p) |
---|
[2e6eac2] | 2573 | "Internal procedure - no help and no example available |
---|
| 2574 | " |
---|
| 2575 | { |
---|
| 2576 | //--- compute numerically (!!!) the zeros of the minimal polynomial |
---|
| 2577 | def R=basering; |
---|
| 2578 | ring S=0,t,dp; |
---|
| 2579 | poly p=imap(R,p); |
---|
| 2580 | def L=laguerre_solve(p,30); |
---|
| 2581 | //!!! practical improvement: |
---|
| 2582 | //!!! testen ob die Nullstellen signifikant verschieden sind |
---|
| 2583 | //!!! und im Notfall Genauigkeit erhoehen |
---|
| 2584 | list re; |
---|
| 2585 | int i; |
---|
| 2586 | for(i=1;i<=size(L);i++) |
---|
| 2587 | { |
---|
| 2588 | re[i]=string(L[i]); |
---|
| 2589 | } |
---|
| 2590 | setring R; |
---|
| 2591 | return(re); |
---|
| 2592 | } |
---|
| 2593 | ////////////////////////////////////////////////////////////////////////////// |
---|
| 2594 | static |
---|
| 2595 | proc simplifyMinpoly(poly p) |
---|
| 2596 | "Internal procedure - no help and no example available |
---|
| 2597 | " |
---|
| 2598 | { |
---|
| 2599 | //--- describe field extension in a simple way |
---|
| 2600 | p=cleardenom(p); |
---|
| 2601 | int n=int(leadcoef(p)); |
---|
| 2602 | int d=deg(p); |
---|
| 2603 | int i,k; |
---|
| 2604 | int re=1; |
---|
| 2605 | number s=1; |
---|
| 2606 | |
---|
| 2607 | list L=primefactors(n); |
---|
| 2608 | |
---|
| 2609 | for(i=1;i<=size(L[1]);i++) |
---|
| 2610 | { |
---|
| 2611 | k=L[2][i] mod d; |
---|
[1f9a84] | 2612 | s=1/number((L[1][i])^(L[2][i] div d)); |
---|
[2e6eac2] | 2613 | if(!k){p=subst(p,t,s*t);} |
---|
| 2614 | } |
---|
| 2615 | p=cleardenom(p); |
---|
| 2616 | n=int(leadcoef(subst(p,t,0))); |
---|
| 2617 | L=primefactors(n); |
---|
| 2618 | for(i=1;i<=size(L[1]);i++) |
---|
| 2619 | { |
---|
| 2620 | k=L[2][i] mod d; |
---|
[1f9a84] | 2621 | s=(L[1][i])^(L[2][i] div d); |
---|
[2e6eac2] | 2622 | if(!k){p=subst(p,t,s*t);} |
---|
| 2623 | } |
---|
| 2624 | p=cleardenom(p); |
---|
| 2625 | return(p); |
---|
| 2626 | } |
---|
| 2627 | /////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 2628 | static proc grad(ideal I) |
---|
[2e6eac2] | 2629 | "Internal procedure - no help and no example available |
---|
| 2630 | " |
---|
| 2631 | { |
---|
| 2632 | //--- computes the number of components over C |
---|
| 2633 | //--- for a prime ideal of height 1 over Q |
---|
| 2634 | def R=basering; |
---|
| 2635 | int n=nvars(basering); |
---|
| 2636 | string mp="poly p=t-1;"; |
---|
| 2637 | string str=string(1); |
---|
| 2638 | list zeroList=string(1); |
---|
| 2639 | int i,j,k,l,d,e,c,mi; |
---|
| 2640 | ideal Istd=std(I); |
---|
| 2641 | intmat interMat; |
---|
| 2642 | d=dim(Istd); |
---|
| 2643 | if(d==-1){return(list(0,0,mp,str,zeroList));} |
---|
| 2644 | if(d!=1){ERROR("ideal is not one-dimensional");} |
---|
| 2645 | ideal Sloc=std(slocus(I)); |
---|
| 2646 | if(deg(Sloc[1])>0) |
---|
| 2647 | { |
---|
| 2648 | //---This is only to test that in case of singularities we have only |
---|
| 2649 | //---one singular point which is a normal crossing |
---|
| 2650 | //---consider the different singular points |
---|
| 2651 | ideal M; |
---|
| 2652 | list pr=minAssGTZ(Sloc); |
---|
| 2653 | if(size(pr)>1){ERROR("grad:more then one singular point");} |
---|
| 2654 | for(l=1;l<=size(pr);l++) |
---|
| 2655 | { |
---|
| 2656 | M=std(pr[l]); |
---|
| 2657 | d=vdim(M); |
---|
| 2658 | if(d!=1) |
---|
| 2659 | { |
---|
| 2660 | //---now we have to extend the field |
---|
| 2661 | if(defined(S)){kill S;} |
---|
| 2662 | ring S=0,x(1..n),lp; |
---|
| 2663 | ideal M=fetch(R,M); |
---|
| 2664 | ideal I=fetch(R,I); |
---|
| 2665 | ideal jmap; |
---|
| 2666 | map phi=S,maxideal(1);; |
---|
| 2667 | ideal Mstd=std(M); |
---|
| 2668 | //---M has to be in general position with respect to lp, i.e. |
---|
| 2669 | //---vdim(M)=deg(M[1]) |
---|
| 2670 | poly p=Mstd[1]; |
---|
| 2671 | e=vdim(Mstd); |
---|
| 2672 | while(e!=deg(p)) |
---|
| 2673 | { |
---|
| 2674 | jmap=randomLast(100); |
---|
| 2675 | phi=S,jmap; |
---|
| 2676 | Mstd=std(phi(M)); |
---|
| 2677 | p=Mstd[1]; |
---|
| 2678 | } |
---|
| 2679 | I=phi(I); |
---|
| 2680 | kill phi; |
---|
| 2681 | //---now it is in general position an M[1] defines the field extension |
---|
| 2682 | //---Q[x]/M over Q |
---|
| 2683 | ring Shelp=0,t,dp; |
---|
| 2684 | ideal helpmap; |
---|
| 2685 | helpmap[n]=t; |
---|
| 2686 | map psi=S,helpmap; |
---|
| 2687 | poly p=psi(p); |
---|
| 2688 | ring T=(0,t),x(1..n),lp; |
---|
| 2689 | poly p=imap(Shelp,p); |
---|
| 2690 | //---we are now in the polynomial ring over the field Q[x]/M |
---|
| 2691 | minpoly=leadcoef(p); |
---|
| 2692 | ideal M=imap(S,Mstd); |
---|
| 2693 | M=M,var(n)-t; |
---|
| 2694 | ideal I=fetch(S,I); |
---|
| 2695 | } |
---|
| 2696 | //---we construct a map phi which maps M to maxideal(1) |
---|
| 2697 | option(redSB); |
---|
| 2698 | ideal Mstd=-simplify(std(M),1); |
---|
| 2699 | option(noredSB); |
---|
| 2700 | for(i=1;i<=n;i++) |
---|
| 2701 | { |
---|
| 2702 | Mstd=subst(Mstd,var(i),-var(i)); |
---|
| 2703 | M[n-i+1]=Mstd[i]; |
---|
| 2704 | } |
---|
| 2705 | M=M[1..n]; |
---|
| 2706 | //---go to the localization with respect to <x> |
---|
| 2707 | if(d!=1) |
---|
| 2708 | { |
---|
| 2709 | ring Tloc=(0,t),x(1..n),ds; |
---|
| 2710 | poly p=imap(Shelp,p); |
---|
| 2711 | minpoly=leadcoef(p); |
---|
| 2712 | ideal M=fetch(T,M); |
---|
| 2713 | map phi=T,M; |
---|
| 2714 | } |
---|
| 2715 | else |
---|
| 2716 | { |
---|
| 2717 | ring Tloc=0,x(1..n),ds; |
---|
| 2718 | ideal M=fetch(R,M); |
---|
| 2719 | map phi=R,M; |
---|
| 2720 | } |
---|
| 2721 | ideal I=phi(I); |
---|
| 2722 | ideal Istd=std(I); |
---|
| 2723 | mi=mi+milnor(Istd); |
---|
| 2724 | if(mi>l) |
---|
| 2725 | { |
---|
| 2726 | ERROR("grad:divisor is really singular"); |
---|
| 2727 | } |
---|
| 2728 | setring R; |
---|
| 2729 | } |
---|
| 2730 | } |
---|
| 2731 | intvec ind=indepSet(Istd,1)[1]; |
---|
| 2732 | for(i=1;i<=n;i++){if(ind[i]) break;} |
---|
| 2733 | //---the i-th variable is the independent one |
---|
| 2734 | ring Shelp=0,x(1..n),dp; |
---|
| 2735 | ideal I=fetch(R,I); |
---|
| 2736 | if(defined(S)){kill S;} |
---|
| 2737 | if(i==1){ring S=(0,x(1)),x(2..n),lp;} |
---|
| 2738 | if(i==n){ring S=(0,x(n)),x(1..n-1),lp;} |
---|
| 2739 | if((i!=1)&&(i!=n)){ring S=(0,x(i)),(x(1..i-1),x(i+1..n)),lp;} |
---|
| 2740 | //---I is zero-dimensional now |
---|
| 2741 | ideal I=imap(Shelp,I); |
---|
| 2742 | ideal Istd=std(I); |
---|
| 2743 | ideal jmap; |
---|
| 2744 | map phi; |
---|
| 2745 | poly p=Istd[1]; |
---|
| 2746 | e=vdim(Istd); |
---|
| 2747 | if(e==1) |
---|
| 2748 | { |
---|
| 2749 | setring R; |
---|
| 2750 | str=string(I); |
---|
| 2751 | list resi=1,interMat,mp,str,zeroList; |
---|
| 2752 | return(resi); |
---|
| 2753 | } |
---|
| 2754 | //---move I to general position with respect to lp |
---|
| 2755 | if(e!=deg(p)) |
---|
| 2756 | { |
---|
| 2757 | jmap=randomLast(5); |
---|
| 2758 | phi=S,jmap; |
---|
| 2759 | Istd=std(phi(I)); |
---|
| 2760 | p=Istd[1]; |
---|
| 2761 | } |
---|
| 2762 | while(e!=deg(p)) |
---|
| 2763 | { |
---|
| 2764 | jmap=randomLast(100); |
---|
| 2765 | phi=S,jmap; |
---|
| 2766 | Istd=std(phi(I)); |
---|
| 2767 | p=Istd[1]; |
---|
| 2768 | } |
---|
| 2769 | setring Shelp; |
---|
| 2770 | poly p=imap(S,p); |
---|
| 2771 | list Q=getMinpoly(p); |
---|
| 2772 | int de=Q[3]; |
---|
| 2773 | mp=Q[1]; |
---|
| 2774 | //!!!diese Stelle effizienter machen |
---|
| 2775 | //!!!minAssGTZ vermeiden durch direkte Betrachtung von |
---|
| 2776 | //!!!p und mp und evtl. Quotientenbildung |
---|
| 2777 | //!!!bisher nicht zeitkritisch |
---|
| 2778 | string Tesr="ring Tes=(0,t),("+varstr(R)+"),dp;"; |
---|
| 2779 | execute(Tesr); |
---|
| 2780 | execute(mp); |
---|
| 2781 | minpoly=leadcoef(p); |
---|
| 2782 | ideal I=fetch(R,I); |
---|
| 2783 | list pr=minAssGTZ(I); |
---|
| 2784 | ideal allgEbene=randomLast(100)[nvars(basering)]; |
---|
| 2785 | int minpts=vdim(std(I+allgEbene)); |
---|
| 2786 | ideal tempi; |
---|
| 2787 | j=1; |
---|
| 2788 | for(i=1;i<=size(pr);i++) |
---|
| 2789 | { |
---|
| 2790 | tempi=std(pr[i]+allgEbene); |
---|
| 2791 | if(vdim(tempi)<minpts) |
---|
| 2792 | { |
---|
| 2793 | minpts=vdim(tempi); |
---|
| 2794 | j=i; |
---|
| 2795 | } |
---|
| 2796 | } |
---|
| 2797 | tempi=pr[j]; |
---|
| 2798 | str=string(tempi); |
---|
| 2799 | kill interMat; |
---|
| 2800 | setring R; |
---|
| 2801 | intmat interMat[de][de]=intersComp(str,mp,Q[2],str,mp,Q[2]); |
---|
| 2802 | list resi=de,interMat,mp,str,Q[2]; |
---|
| 2803 | return(resi); |
---|
| 2804 | } |
---|
| 2805 | //////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 2806 | static proc Kontakt(ideal I, ideal K) |
---|
[2e6eac2] | 2807 | "Internal procedure - no help and no example available |
---|
| 2808 | " |
---|
| 2809 | { |
---|
| 2810 | //---Let K be a prime ideal and I an ideal not contained in K |
---|
| 2811 | //---computes a maximalideal M=<x(1)-a1,...,x(n)-an>, ai in a field |
---|
| 2812 | //---extension of Q, containing I+K and an integer a |
---|
| 2813 | //---such that in the localization of the polynomial ring with |
---|
| 2814 | //---respect to M the ideal I is not contained in K+M^a+1 but in M^a in |
---|
| 2815 | def R=basering; |
---|
| 2816 | int n=nvars(basering); |
---|
| 2817 | int i,j,k,d,e; |
---|
| 2818 | ideal J=std(I+K); |
---|
| 2819 | if(dim(J)==-1){return(0);} |
---|
| 2820 | ideal W; |
---|
| 2821 | //---choice of the maximal ideal M |
---|
| 2822 | for(i=1;i<=n;i++) |
---|
| 2823 | { |
---|
| 2824 | W=std(J,var(i)); |
---|
| 2825 | d=dim(W); |
---|
| 2826 | if(d==0) break; |
---|
| 2827 | } |
---|
| 2828 | i=1;k=2; |
---|
| 2829 | while((d)&&(i<n)) |
---|
| 2830 | { |
---|
| 2831 | W=std(J,var(i)+var(k)); |
---|
| 2832 | d=dim(W); |
---|
| 2833 | if(k==n){i++;k=i;} |
---|
| 2834 | if(k<n){k++;} |
---|
| 2835 | } |
---|
| 2836 | while(d) |
---|
| 2837 | { |
---|
| 2838 | W=std(J,randomid(maxideal(1))[1]); |
---|
| 2839 | d=dim(W); |
---|
| 2840 | } |
---|
| 2841 | //---now we have a collection om maximalideals and choose one with dim Q[x]/M |
---|
| 2842 | //---minimal |
---|
| 2843 | list pr=minAssGTZ(W); |
---|
| 2844 | d=vdim(std(pr[1])); |
---|
| 2845 | k=1; |
---|
| 2846 | for(i=2;i<=size(pr);i++) |
---|
| 2847 | { |
---|
| 2848 | if(d==1) break; |
---|
| 2849 | e=vdim(std(pr[i])); |
---|
| 2850 | if(e<d){k=i;d=e;} |
---|
| 2851 | } |
---|
| 2852 | //---M is fixed now |
---|
| 2853 | //---if dim Q[x]/M =1 we localize at M |
---|
| 2854 | ideal M=pr[k]; |
---|
| 2855 | if(d!=1) |
---|
| 2856 | { |
---|
| 2857 | //---now we have to extend the field |
---|
| 2858 | if(defined(S)){kill S;} |
---|
| 2859 | ring S=0,x(1..n),lp; |
---|
| 2860 | ideal M=fetch(R,M); |
---|
| 2861 | ideal I=fetch(R,I); |
---|
| 2862 | ideal K=fetch(R,K); |
---|
| 2863 | ideal jmap; |
---|
| 2864 | map phi=S,maxideal(1);; |
---|
| 2865 | ideal Mstd=std(M); |
---|
| 2866 | //---M has to be in general position with respect to lp, i.e. |
---|
| 2867 | //---vdim(M)=deg(M[1]) |
---|
| 2868 | poly p=Mstd[1]; |
---|
| 2869 | e=vdim(Mstd); |
---|
| 2870 | while(e!=deg(p)) |
---|
| 2871 | { |
---|
| 2872 | jmap=randomLast(100); |
---|
| 2873 | phi=S,jmap; |
---|
| 2874 | Mstd=std(phi(M)); |
---|
| 2875 | p=Mstd[1]; |
---|
| 2876 | } |
---|
| 2877 | I=phi(I); |
---|
| 2878 | K=phi(K); |
---|
| 2879 | kill phi; |
---|
| 2880 | //---now it is in general position an M[1] defines the field extension |
---|
| 2881 | //---Q[x]/M over Q |
---|
| 2882 | ring Shelp=0,t,dp; |
---|
| 2883 | ideal helpmap; |
---|
| 2884 | helpmap[n]=t; |
---|
| 2885 | map psi=S,helpmap; |
---|
| 2886 | poly p=psi(p); |
---|
| 2887 | ring T=(0,t),x(1..n),lp; |
---|
| 2888 | poly p=imap(Shelp,p); |
---|
| 2889 | //---we are now in the polynomial ring over the field Q[x]/M |
---|
| 2890 | minpoly=leadcoef(p); |
---|
| 2891 | ideal M=imap(S,Mstd); |
---|
| 2892 | M=M,var(n)-t; |
---|
| 2893 | ideal I=fetch(S,I); |
---|
| 2894 | ideal K=fetch(S,K); |
---|
| 2895 | } |
---|
| 2896 | //---we construct a map phi which maps M to maxideal(1) |
---|
| 2897 | option(redSB); |
---|
| 2898 | ideal Mstd=-simplify(std(M),1); |
---|
| 2899 | option(noredSB); |
---|
| 2900 | for(i=1;i<=n;i++) |
---|
| 2901 | { |
---|
| 2902 | Mstd=subst(Mstd,var(i),-var(i)); |
---|
| 2903 | M[n-i+1]=Mstd[i]; |
---|
| 2904 | } |
---|
| 2905 | M=M[1..n]; |
---|
| 2906 | //---go to the localization with respect to <x> |
---|
| 2907 | if(d!=1) |
---|
| 2908 | { |
---|
| 2909 | ring Tloc=(0,t),x(1..n),ds; |
---|
| 2910 | poly p=imap(Shelp,p); |
---|
| 2911 | minpoly=leadcoef(p); |
---|
| 2912 | ideal M=fetch(T,M); |
---|
| 2913 | map phi=T,M; |
---|
| 2914 | } |
---|
| 2915 | else |
---|
| 2916 | { |
---|
| 2917 | ring Tloc=0,x(1..n),ds; |
---|
| 2918 | ideal M=fetch(R,M); |
---|
| 2919 | map phi=R,M; |
---|
| 2920 | } |
---|
| 2921 | ideal K=phi(K); |
---|
| 2922 | ideal I=phi(I); |
---|
| 2923 | //---compute the order of I in (Q[x]/M)[[x]]/K |
---|
| 2924 | k=1;d=0; |
---|
| 2925 | while(!d) |
---|
| 2926 | { |
---|
| 2927 | k++; |
---|
| 2928 | d=size(reduce(I,std(maxideal(k)+K))); |
---|
| 2929 | } |
---|
| 2930 | setring R; |
---|
| 2931 | return(k-1); |
---|
| 2932 | } |
---|
| 2933 | example |
---|
| 2934 | {"EXAMPLE:"; |
---|
| 2935 | echo = 2; |
---|
| 2936 | ring r = 0,(x,y,z),dp; |
---|
| 2937 | ideal I=x4+z4+1; |
---|
| 2938 | ideal K=x+y2+z2; |
---|
| 2939 | Kontakt(I,K); |
---|
| 2940 | } |
---|
| 2941 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 2942 | static proc abstractNC(list BO) |
---|
[2e6eac2] | 2943 | "Internal procedure - no help and no example available |
---|
| 2944 | " |
---|
| 2945 | { |
---|
| 2946 | //--- check normal crossing property |
---|
| 2947 | //--- used for passing from embedded to non-embedded resolution |
---|
| 2948 | //---------------------------------------------------------------------------- |
---|
| 2949 | // Initialization |
---|
| 2950 | //---------------------------------------------------------------------------- |
---|
| 2951 | int i,k,j,flag; |
---|
| 2952 | list L; |
---|
| 2953 | ideal J; |
---|
| 2954 | if(dim(std(cent))>0){return(1);} |
---|
| 2955 | //---------------------------------------------------------------------------- |
---|
| 2956 | // check each exceptional divisor on V(J) |
---|
| 2957 | //---------------------------------------------------------------------------- |
---|
| 2958 | for(i=1;i<=size(BO[4]);i++) |
---|
| 2959 | { |
---|
| 2960 | if(dim(std(BO[2]+BO[4][i]))>0) |
---|
| 2961 | { |
---|
| 2962 | //--- really something to do |
---|
| 2963 | J=radical(BO[4][i]+BO[2]); |
---|
| 2964 | if(deg(std(slocus(J))[1])!=0) |
---|
| 2965 | { |
---|
| 2966 | if(!nodes(J)) |
---|
| 2967 | { |
---|
| 2968 | //--- really singular, not only nodes ==> not normal crossing |
---|
| 2969 | return(0); |
---|
| 2970 | } |
---|
| 2971 | } |
---|
| 2972 | for(k=1;k<=size(L);k++) |
---|
| 2973 | { |
---|
| 2974 | //--- run through previously considered divisors |
---|
| 2975 | //--- we do not want to bother with the same one twice |
---|
| 2976 | if((size(reduce(J,std(L[k])))==0)&&(size(reduce(L[k],std(J)))==0)) |
---|
| 2977 | { |
---|
| 2978 | //--- already considered this one |
---|
| 2979 | flag=1;break; |
---|
| 2980 | } |
---|
| 2981 | //--- drop previously considered exceptional divisors from the current one |
---|
| 2982 | J=sat(J,L[k])[1]; |
---|
| 2983 | if(deg(std(J)[1])==0) |
---|
| 2984 | { |
---|
| 2985 | //--- nothing remaining |
---|
| 2986 | flag=1;break; |
---|
| 2987 | } |
---|
| 2988 | } |
---|
| 2989 | if(flag==0) |
---|
| 2990 | { |
---|
| 2991 | //--- add exceptional divisor to the list |
---|
| 2992 | L[size(L)+1]=J; |
---|
| 2993 | } |
---|
| 2994 | flag=0; |
---|
| 2995 | } |
---|
| 2996 | } |
---|
| 2997 | //--------------------------------------------------------------------------- |
---|
| 2998 | // check intersection properties between different exceptional divisors |
---|
| 2999 | //--------------------------------------------------------------------------- |
---|
| 3000 | for(k=1;k<size(L);k++) |
---|
| 3001 | { |
---|
| 3002 | for(i=k+1;i<=size(L);i++) |
---|
| 3003 | { |
---|
| 3004 | if(!nodes(intersect(L[k],L[i]))) |
---|
| 3005 | { |
---|
| 3006 | //--- divisors Ek and Ei do not meet in a node but in a singularity |
---|
| 3007 | //--- which is not allowed to occur ==> not normal crossing |
---|
| 3008 | return(0); |
---|
| 3009 | } |
---|
| 3010 | for(j=i+1;j<=size(L);j++) |
---|
| 3011 | { |
---|
| 3012 | if(deg(std(L[i]+L[j]+L[k])[1])>0) |
---|
| 3013 | { |
---|
| 3014 | //--- three divisors meet simultaneously ==> not normal crossing |
---|
| 3015 | return(0); |
---|
| 3016 | } |
---|
| 3017 | } |
---|
| 3018 | } |
---|
| 3019 | } |
---|
| 3020 | //--- we reached this point ==> normal crossing |
---|
| 3021 | return(1); |
---|
| 3022 | } |
---|
| 3023 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 3024 | static proc nodes(ideal J) |
---|
[2e6eac2] | 3025 | "Internal procedure - no help and no example available |
---|
| 3026 | " |
---|
| 3027 | { |
---|
| 3028 | //--- check whether at most nodes occur as singularities |
---|
| 3029 | ideal K=std(slocus(J)); |
---|
| 3030 | if(deg(K[1])==0){return(1);} |
---|
| 3031 | if(dim(K)>0){return(0);} |
---|
| 3032 | if(vdim(K)!=vdim(std(radical(K)))){return(0);} |
---|
| 3033 | return(1); |
---|
| 3034 | } |
---|
| 3035 | ////////////////////////////////////////////////////////////////////////////// |
---|
| 3036 | |
---|
| 3037 | proc intersectionDiv(list re) |
---|
| 3038 | "USAGE: intersectionDiv(L); |
---|
| 3039 | @* L = list of rings |
---|
| 3040 | ASSUME: L is output of resolution of singularities |
---|
| 3041 | (only case of isolated surface singularities) |
---|
| 3042 | COMPUTE: intersection matrix and genera of the exceptional divisors |
---|
| 3043 | (considered as curves on the strict transform) |
---|
| 3044 | RETURN: list l, where |
---|
| 3045 | l[1]: intersection matrix of exceptional divisors |
---|
| 3046 | l[2]: intvec, genera of exceptional divisors |
---|
| 3047 | l[3]: divisorList, encoding the identification of the divisors |
---|
| 3048 | EXAMPLE: example intersectionDiv; shows an example |
---|
| 3049 | " |
---|
| 3050 | { |
---|
| 3051 | //---------------------------------------------------------------------------- |
---|
| 3052 | //--- Computes in case of surface singularities (non-embedded resolution): |
---|
| 3053 | //--- the intersection of the divisors (on the surface) |
---|
| 3054 | //--- assuming that re=resolve(J) |
---|
| 3055 | //---------------------------------------------------------------------------- |
---|
| 3056 | def R=basering; |
---|
| 3057 | //---Test whether we are in the irreducible surface case |
---|
| 3058 | def S=re[2][1]; |
---|
| 3059 | setring S; |
---|
| 3060 | BO[2]=BO[2]+BO[1]; // make sure we are living in the smooth W |
---|
| 3061 | if(dim(std(BO[2]))!=2) |
---|
| 3062 | { |
---|
| 3063 | ERROR("The given original object is not a surface"); |
---|
| 3064 | } |
---|
| 3065 | if(dim(std(slocus(BO[2])))>0) |
---|
| 3066 | { |
---|
| 3067 | ERROR("The given original object has non-isolated singularities."); |
---|
| 3068 | } |
---|
| 3069 | setring R; |
---|
| 3070 | //---------------------------------------------------------------------------- |
---|
| 3071 | // Compute a non-embedded resolution from the given embedded one by |
---|
| 3072 | // dropping redundant trailing blow-ups |
---|
| 3073 | //---------------------------------------------------------------------------- |
---|
| 3074 | list resu,tmpiden,templist; |
---|
| 3075 | intvec divcomp; |
---|
| 3076 | int i,j,k,offset1,offset2,a,b,c,d,q,found; |
---|
| 3077 | //--- compute non-embedded resolution |
---|
| 3078 | list abst=abstractR(re); |
---|
| 3079 | intvec endiv=abst[1]; |
---|
| 3080 | intvec deleted=abst[2]; |
---|
| 3081 | //--- identify the divisors in the various final charts |
---|
| 3082 | list iden=collectDiv(re,deleted)[2]; |
---|
| 3083 | // list of final divisors |
---|
| 3084 | list iden0=iden; // backup copy of iden for later use |
---|
| 3085 | |
---|
| 3086 | iden=delete(iden,size(iden)); // drop list of endRings from iden |
---|
| 3087 | //--------------------------------------------------------------------------- |
---|
| 3088 | // In iden, only the final charts should be listed, whereas iden0 contains |
---|
| 3089 | // everything. |
---|
| 3090 | //--------------------------------------------------------------------------- |
---|
| 3091 | for(i=1;i<=size(iden);i++) |
---|
| 3092 | { |
---|
| 3093 | k=size(iden[i]); |
---|
| 3094 | tmpiden=iden[i]; |
---|
| 3095 | for(j=k;j>0;j--) |
---|
| 3096 | { |
---|
| 3097 | if(!endiv[iden[i][j][1]]) |
---|
| 3098 | { |
---|
| 3099 | //---not a final chart |
---|
| 3100 | tmpiden=delete(tmpiden,j); |
---|
| 3101 | } |
---|
| 3102 | } |
---|
| 3103 | if(size(tmpiden)==0) |
---|
| 3104 | { |
---|
| 3105 | //--- oops, this divisor does not appear in final charts |
---|
| 3106 | iden=delete(iden,i); |
---|
| 3107 | continue; |
---|
| 3108 | } |
---|
| 3109 | else |
---|
| 3110 | { |
---|
| 3111 | iden[i]=tmpiden; |
---|
| 3112 | } |
---|
| 3113 | } |
---|
| 3114 | //--------------------------------------------------------------------------- |
---|
| 3115 | // Even though the exceptional divisors were irreducible in the embedded |
---|
| 3116 | // case, they may very well have become reducible after intersection with |
---|
| 3117 | // the strict transform of the original object. |
---|
| 3118 | // ===> compute a decomposition for each divisor in each of the final charts |
---|
| 3119 | // and change the entries of iden accordingly |
---|
| 3120 | // In particular, it is important to keep track of the identification of the |
---|
| 3121 | // components of the divisors in each of the charts |
---|
| 3122 | //--------------------------------------------------------------------------- |
---|
| 3123 | int n=size(iden); |
---|
| 3124 | for(i=1;i<=size(re[2]);i++) |
---|
| 3125 | { |
---|
| 3126 | if(endiv[i]) |
---|
| 3127 | { |
---|
| 3128 | def SN=re[2][i]; |
---|
| 3129 | setring SN; |
---|
| 3130 | if(defined(dcE)){kill dcE;} |
---|
| 3131 | list dcE=decompEinX(BO); // decomposition of exceptional divisors |
---|
| 3132 | export(dcE); |
---|
| 3133 | setring R; |
---|
| 3134 | kill SN; |
---|
| 3135 | } |
---|
| 3136 | } |
---|
| 3137 | if(defined(tmpiden)){kill tmpiden;} |
---|
| 3138 | list tmpiden=iden; |
---|
| 3139 | for(i=1;i<=size(iden);i++) |
---|
| 3140 | { |
---|
| 3141 | for(j=size(iden[i]);j>0;j--) |
---|
| 3142 | { |
---|
| 3143 | def SN=re[2][iden[i][j][1]]; |
---|
| 3144 | setring SN; |
---|
| 3145 | if(size(dcE[iden[i][j][2]])==1) |
---|
| 3146 | { |
---|
| 3147 | if(dcE[iden[i][j][2]][1][2]==0) |
---|
| 3148 | { |
---|
| 3149 | tmpiden[i]=delete(tmpiden[i],j); |
---|
| 3150 | } |
---|
| 3151 | } |
---|
| 3152 | setring R; |
---|
| 3153 | kill SN; |
---|
| 3154 | } |
---|
| 3155 | } |
---|
| 3156 | for(i=size(tmpiden);i>0;i--) |
---|
| 3157 | { |
---|
| 3158 | if(size(tmpiden[i])==0) |
---|
| 3159 | { |
---|
| 3160 | tmpiden=delete(tmpiden,i); |
---|
| 3161 | } |
---|
| 3162 | } |
---|
| 3163 | iden=tmpiden; |
---|
| 3164 | kill tmpiden; |
---|
| 3165 | list tmpiden; |
---|
| 3166 | //--- change entries of iden accordingly |
---|
| 3167 | for(i=1;i<=size(iden);i++) |
---|
| 3168 | { |
---|
| 3169 | //--- first set up new entries in iden if necessary - using the first chart |
---|
| 3170 | //--- in which we see the respective exceptional divisor |
---|
| 3171 | if(defined(S)){kill S;} |
---|
| 3172 | def S=re[2][iden[i][1][1]]; |
---|
| 3173 | //--- considering first entry for i-th divisor |
---|
| 3174 | setring S; |
---|
| 3175 | a=size(dcE[iden[i][1][2]]); |
---|
| 3176 | for(j=1;j<=a;j++) |
---|
| 3177 | { |
---|
| 3178 | //--- reducible - add to the list considering each component as an exceptional |
---|
| 3179 | //--- divisor in its own right |
---|
| 3180 | list tl; |
---|
| 3181 | tl[1]=intvec(iden[i][1][1],iden[i][1][2],j); |
---|
| 3182 | tmpiden[size(tmpiden)+1]=tl; |
---|
| 3183 | kill tl; |
---|
| 3184 | } |
---|
| 3185 | //--- now identify the components in the other charts w.r.t. the ones in the |
---|
| 3186 | //--- first chart which have already been added to the list |
---|
| 3187 | for(j=2;j<=size(iden[i]);j++) |
---|
| 3188 | { |
---|
| 3189 | //--- considering remaining entries for the same original divisor |
---|
| 3190 | if(defined(S2)){kill S2;} |
---|
| 3191 | def S2=re[2][iden[i][j][1]]; |
---|
| 3192 | setring S2; |
---|
| 3193 | //--- determine common parent of this ring and re[2][iden[i][1][1]] |
---|
| 3194 | if(defined(opath)){kill opath;} |
---|
| 3195 | def opath=imap(S,path); |
---|
| 3196 | b=1; |
---|
| 3197 | while(opath[1,b]==path[1,b]) |
---|
| 3198 | { |
---|
| 3199 | b++; |
---|
| 3200 | if((b>ncols(path))||(b>ncols(opath))) break; |
---|
| 3201 | } |
---|
| 3202 | if(defined(li1)){kill li1;} |
---|
| 3203 | list li1; |
---|
| 3204 | //--- fetch the components we have considered in re[2][iden[i][1][1]] |
---|
| 3205 | //--- via the resolution tree |
---|
| 3206 | for(k=1;k<=a;k++) |
---|
| 3207 | { |
---|
| 3208 | string tempstr="dcE["+string(eval(iden[i][1][2]))+"]["+string(k)+"][1]"; |
---|
| 3209 | if(defined(id1)){kill id1;} |
---|
| 3210 | ideal id1=fetchInTree(re,iden[i][1][1],int(leadcoef(path[1,b-1])), |
---|
| 3211 | iden[i][j][1],tempstr,iden0,1); |
---|
| 3212 | kill tempstr; |
---|
| 3213 | li1[k]=radical(id1); // for comparison only the geometric |
---|
| 3214 | // object matters |
---|
| 3215 | kill id1; |
---|
| 3216 | } |
---|
| 3217 | //--- compare the components we have fetched with the components in the |
---|
| 3218 | //--- current ring |
---|
| 3219 | for(k=1;k<=size(dcE[iden[i][j][2]]);k++) |
---|
| 3220 | { |
---|
| 3221 | found=0; |
---|
| 3222 | for(b=1;b<=size(li1);b++) |
---|
| 3223 | { |
---|
| 3224 | if((size(reduce(li1[b],std(dcE[iden[i][j][2]][k][1])))==0)&& |
---|
| 3225 | (size(reduce(dcE[iden[i][j][2]][k][1],std(li1[b]+BO[2])))==0)) |
---|
| 3226 | { |
---|
| 3227 | li1[b]=ideal(1); |
---|
| 3228 | tmpiden[size(tmpiden)-a+b][size(tmpiden[size(tmpiden)-a+b])+1]= |
---|
| 3229 | intvec(iden[i][j][1],iden[i][j][2],k); |
---|
| 3230 | found=1; |
---|
| 3231 | break; |
---|
| 3232 | } |
---|
| 3233 | } |
---|
| 3234 | if(!found) |
---|
| 3235 | { |
---|
| 3236 | if(!defined(repair)) |
---|
| 3237 | { |
---|
| 3238 | list repair; |
---|
| 3239 | repair[1]=list(intvec(iden[i][j][1],iden[i][j][2],k)); |
---|
| 3240 | } |
---|
| 3241 | else |
---|
| 3242 | { |
---|
| 3243 | for(c=1;c<=size(repair);c++) |
---|
| 3244 | { |
---|
| 3245 | for(d=1;d<=size(repair[c]);d++) |
---|
| 3246 | { |
---|
| 3247 | if(defined(opath)) {kill opath;} |
---|
| 3248 | def opath=imap(re[2][repair[c][d][1]],path); |
---|
| 3249 | q=0; |
---|
| 3250 | while(path[1,q+1]==opath[1,q+1]) |
---|
| 3251 | { |
---|
| 3252 | q++; |
---|
| 3253 | if((q>ncols(path)-1)||(q>ncols(opath)-1)) break; |
---|
| 3254 | } |
---|
| 3255 | q=int(leadcoef(path[1,q])); |
---|
| 3256 | string tempstr="dcE["+string(eval(repair[c][d][2]))+"]["+string(eval(repair[c][d][3]))+"][1]"; |
---|
| 3257 | if(defined(id1)){kill id1;} |
---|
| 3258 | ideal id1=fetchInTree(re,repair[c][d][1],q, |
---|
| 3259 | iden[i][j][1],tempstr,iden0,1); |
---|
| 3260 | kill tempstr; |
---|
| 3261 | //!!! sind die nicht schon radical? |
---|
| 3262 | id1=radical(id1); // for comparison |
---|
| 3263 | // only the geometric |
---|
| 3264 | // object matters |
---|
| 3265 | if((size(reduce(dcE[iden[i][j][2]][k][1],std(id1+BO[2])))==0)&& |
---|
| 3266 | (size(reduce(id1+BO[2],std(dcE[iden[i][j][2]][k][1])))==0)) |
---|
| 3267 | { |
---|
| 3268 | repair[c][size(repair[c])+1]=intvec(iden[i][j][1],iden[i][j][2],k); |
---|
| 3269 | break; |
---|
| 3270 | } |
---|
| 3271 | } |
---|
| 3272 | if(d<=size(repair[c])) |
---|
| 3273 | { |
---|
| 3274 | break; |
---|
| 3275 | } |
---|
| 3276 | } |
---|
| 3277 | if(c>size(repair)) |
---|
| 3278 | { |
---|
| 3279 | repair[size(repair)+1]=list(intvec(iden[i][j][1],iden[i][j][2],k)); |
---|
| 3280 | } |
---|
| 3281 | } |
---|
| 3282 | } |
---|
| 3283 | } |
---|
| 3284 | } |
---|
| 3285 | if(defined(repair)) |
---|
| 3286 | { |
---|
| 3287 | for(c=1;c<=size(repair);c++) |
---|
| 3288 | { |
---|
| 3289 | tmpiden[size(tmpiden)+1]=repair[c]; |
---|
| 3290 | } |
---|
| 3291 | kill repair; |
---|
| 3292 | } |
---|
| 3293 | } |
---|
| 3294 | setring R; |
---|
| 3295 | for(i=size(tmpiden);i>0;i--) |
---|
| 3296 | { |
---|
| 3297 | if(size(tmpiden[i])==0) |
---|
| 3298 | { |
---|
| 3299 | tmpiden=delete(tmpiden,i); |
---|
| 3300 | continue; |
---|
| 3301 | } |
---|
| 3302 | } |
---|
| 3303 | iden=tmpiden; // store the modified divisor list |
---|
| 3304 | kill tmpiden; // and clean up temporary objects |
---|
| 3305 | //--------------------------------------------------------------------------- |
---|
| 3306 | // Now we have decomposed everything into irreducible components over Q, |
---|
| 3307 | // but over C there might still be some reducible ones left: |
---|
| 3308 | // Determine the number of components over C. |
---|
| 3309 | //--------------------------------------------------------------------------- |
---|
| 3310 | n=0; |
---|
| 3311 | for(i=1;i<=size(iden);i++) |
---|
| 3312 | { |
---|
| 3313 | if(defined(S)) {kill S;} |
---|
| 3314 | def S=re[2][iden[i][1][1]]; |
---|
| 3315 | setring S; |
---|
| 3316 | divcomp[i]=ncols(dcE[iden[i][1][2]][iden[i][1][3]][4]); |
---|
| 3317 | // number of components of the Q-irreducible curve dcE[iden[i][1][2]] |
---|
| 3318 | n=n+divcomp[i]; |
---|
| 3319 | setring R; |
---|
| 3320 | } |
---|
| 3321 | //--------------------------------------------------------------------------- |
---|
| 3322 | // set up the entries Inters[i,j] , i!=j, in the intersection matrix: |
---|
| 3323 | // we have to compute the intersection of the exceptional divisors (over C) |
---|
| 3324 | // i.e. we have to work in over appropriate algebraic extension of Q. |
---|
| 3325 | // (1) plug the intersection matrices of the components of the same Q-irred. |
---|
| 3326 | // divisor into the correct position in the intersection matrix |
---|
| 3327 | // (2) for comparison of Ei,k and Ej,l move to a chart where both divisors |
---|
| 3328 | // are present, fetch the components from the very first chart containing |
---|
| 3329 | // the respective divisor and then compare by using intersComp |
---|
| 3330 | // (4) put the result into the correct position in the integer matrix Inters |
---|
| 3331 | //--------------------------------------------------------------------------- |
---|
| 3332 | //--- some initialization |
---|
| 3333 | int comPai,comPaj; |
---|
| 3334 | intvec v,w; |
---|
| 3335 | intmat Inters[n][n]; |
---|
| 3336 | //--- run through all Q-irreducible exceptional divisors |
---|
| 3337 | for(i=1;i<=size(iden);i++) |
---|
| 3338 | { |
---|
| 3339 | if(divcomp[i]>1) |
---|
| 3340 | { |
---|
| 3341 | //--- (1) put the intersection matrix for Ei,k with Ei,l into the correct place |
---|
| 3342 | for(k=1;k<=size(iden[i]);k++) |
---|
| 3343 | { |
---|
| 3344 | if(defined(tempmat)){kill tempmat;} |
---|
| 3345 | intmat tempmat=imap(re[2][iden[i][k][1]],dcE)[iden[i][k][2]][iden[i][k][3]][4]; |
---|
| 3346 | if(size(ideal(tempmat))!=0) |
---|
| 3347 | { |
---|
| 3348 | Inters[i+offset1..(i+offset1+divcomp[i]-1), |
---|
| 3349 | i+offset1..(i+offset1+divcomp[i]-1)]= |
---|
| 3350 | tempmat[1..nrows(tempmat),1..ncols(tempmat)]; |
---|
| 3351 | break; |
---|
| 3352 | } |
---|
| 3353 | kill tempmat; |
---|
| 3354 | } |
---|
| 3355 | } |
---|
| 3356 | offset2=offset1+divcomp[i]-1; |
---|
| 3357 | //--- set up the components over C of the i-th exceptional divisor |
---|
| 3358 | if(defined(S)){kill S;} |
---|
| 3359 | def S=re[2][iden[i][1][1]]; |
---|
| 3360 | setring S; |
---|
| 3361 | if(defined(idlisti)) {kill idlisti;} |
---|
| 3362 | list idlisti; |
---|
| 3363 | idlisti[1]=dcE[iden[i][1][2]][iden[i][1][3]][6]; |
---|
| 3364 | export(idlisti); |
---|
| 3365 | setring R; |
---|
| 3366 | //--- run through the remaining exceptional divisors and check whether they |
---|
| 3367 | //--- have a chart in common with the i-th divisor |
---|
| 3368 | for(j=i+1;j<=size(iden);j++) |
---|
| 3369 | { |
---|
| 3370 | kill templist; |
---|
| 3371 | list templist; |
---|
| 3372 | for(k=1;k<=size(iden[i]);k++) |
---|
| 3373 | { |
---|
| 3374 | intvec tiv2=findInIVList(1,iden[i][k][1],iden[j]); |
---|
| 3375 | if(size(tiv2)!=1) |
---|
| 3376 | { |
---|
| 3377 | //--- tiv2[1] is a common chart for the divisors i and j |
---|
| 3378 | tiv2[4..6]=iden[i][k]; |
---|
| 3379 | templist[size(templist)+1]=tiv2; |
---|
| 3380 | } |
---|
| 3381 | kill tiv2; |
---|
| 3382 | } |
---|
| 3383 | if(size(templist)==0) |
---|
| 3384 | { |
---|
| 3385 | //--- the two (Q-irred) divisors do not appear in any chart simultaneously |
---|
| 3386 | offset2=offset2+divcomp[j]-1; |
---|
| 3387 | j++; |
---|
| 3388 | continue; |
---|
| 3389 | } |
---|
| 3390 | for(k=1;k<=size(templist);k++) |
---|
| 3391 | { |
---|
| 3392 | if(defined(S)) {kill S;} |
---|
| 3393 | //--- set up the components over C of the j-th exceptional divisor |
---|
| 3394 | def S=re[2][iden[j][1][1]]; |
---|
| 3395 | setring S; |
---|
| 3396 | if(defined(idlistj)) {kill idlistj;} |
---|
| 3397 | list idlistj; |
---|
| 3398 | idlistj[1]=dcE[iden[j][1][2]][iden[j][1][3]][6]; |
---|
| 3399 | export(idlistj); |
---|
| 3400 | if(defined(opath)){kill opath;} |
---|
| 3401 | def opath=imap(re[2][templist[k][1]],path); |
---|
| 3402 | comPaj=1; |
---|
| 3403 | while(opath[1,comPaj]==path[1,comPaj]) |
---|
| 3404 | { |
---|
| 3405 | comPaj++; |
---|
| 3406 | if((comPaj>ncols(opath))||(comPaj>ncols(path))) break; |
---|
| 3407 | } |
---|
| 3408 | comPaj=int(leadcoef(path[1,comPaj-1])); |
---|
| 3409 | setring R; |
---|
| 3410 | kill S; |
---|
| 3411 | def S=re[2][iden[i][1][1]]; |
---|
| 3412 | setring S; |
---|
| 3413 | if(defined(opath)){kill opath;} |
---|
| 3414 | def opath=imap(re[2][templist[k][1]],path); |
---|
| 3415 | comPai=1; |
---|
| 3416 | while(opath[1,comPai]==path[1,comPai]) |
---|
| 3417 | { |
---|
| 3418 | comPai++; |
---|
| 3419 | if((comPai>ncols(opath))||(comPai>ncols(path))) break; |
---|
| 3420 | } |
---|
| 3421 | comPai=int(leadcoef(opath[1,comPai-1])); |
---|
| 3422 | setring R; |
---|
| 3423 | kill S; |
---|
| 3424 | def S=re[2][templist[k][1]]; |
---|
| 3425 | setring S; |
---|
| 3426 | if(defined(il)) {kill il;} |
---|
| 3427 | if(defined(jl)) {kill jl;} |
---|
| 3428 | if(defined(str1)) {kill str1;} |
---|
| 3429 | if(defined(str2)) {kill str2;} |
---|
| 3430 | string str1="idlisti"; |
---|
| 3431 | string str2="idlistj"; |
---|
| 3432 | attrib(str1,"algext",imap(re[2][iden[i][1][1]],dcE)[iden[i][1][2]][iden[i][1][3]][5]); |
---|
| 3433 | attrib(str2,"algext",imap(re[2][iden[j][1][1]],dcE)[iden[j][1][2]][iden[j][1][3]][5]); |
---|
| 3434 | list il=fetchInTree(re,iden[i][1][1],comPai, |
---|
| 3435 | templist[k][1],str1,iden0,1); |
---|
| 3436 | list jl=fetchInTree(re,iden[j][1][1],comPaj, |
---|
| 3437 | templist[k][1],str2,iden0,1); |
---|
| 3438 | list nulli=imap(re[2][iden[i][1][1]],dcE)[iden[i][1][2]][iden[i][1][3]][7]; |
---|
| 3439 | list nullj=imap(re[2][iden[j][1][1]],dcE)[iden[j][1][2]][iden[j][1][3]][7]; |
---|
| 3440 | string mpi=imap(re[2][iden[i][1][1]],dcE)[iden[i][1][2]][iden[i][1][3]][5]; |
---|
| 3441 | string mpj=imap(re[2][iden[j][1][1]],dcE)[iden[j][1][2]][iden[j][1][3]][5]; |
---|
| 3442 | if(defined(tintMat)){kill tintMat;} |
---|
| 3443 | intmat tintMat=intersComp(il[1],mpi,nulli,jl[1],mpj,nullj); |
---|
| 3444 | kill mpi; |
---|
| 3445 | kill mpj; |
---|
| 3446 | kill nulli; |
---|
| 3447 | kill nullj; |
---|
| 3448 | for(a=1;a<=divcomp[i];a++) |
---|
| 3449 | { |
---|
| 3450 | for(b=1;b<=divcomp[j];b++) |
---|
| 3451 | { |
---|
| 3452 | if(tintMat[a,b]!=0) |
---|
| 3453 | { |
---|
| 3454 | Inters[i+offset1+a-1,j+offset2+b-1]=tintMat[a,b]; |
---|
| 3455 | Inters[j+offset2+b-1,i+offset1+a-1]=tintMat[a,b]; |
---|
| 3456 | } |
---|
| 3457 | } |
---|
| 3458 | } |
---|
| 3459 | } |
---|
| 3460 | offset2=offset2+divcomp[j]-1; |
---|
| 3461 | } |
---|
| 3462 | offset1=offset1+divcomp[i]-1; |
---|
| 3463 | } |
---|
| 3464 | Inters=addSelfInter(re,Inters,iden,iden0,endiv); |
---|
| 3465 | intvec GenusIden; |
---|
| 3466 | |
---|
| 3467 | list tl_genus; |
---|
| 3468 | a=1; |
---|
| 3469 | for(i=1;i<=size(iden);i++) |
---|
| 3470 | { |
---|
| 3471 | tl_genus=genus_E(re,iden0,iden[i][1]); |
---|
| 3472 | for(j=1;j<=tl_genus[2];j++) |
---|
| 3473 | { |
---|
| 3474 | GenusIden[a]=tl_genus[1]; |
---|
| 3475 | a++; |
---|
| 3476 | } |
---|
| 3477 | } |
---|
| 3478 | |
---|
| 3479 | list retlist=Inters,GenusIden,iden,divcomp; |
---|
| 3480 | return(retlist); |
---|
| 3481 | } |
---|
| 3482 | example |
---|
| 3483 | {"EXAMPLE:"; |
---|
| 3484 | echo = 2; |
---|
| 3485 | ring r = 0,(x(1..3)),dp(3); |
---|
| 3486 | ideal J=x(3)^5+x(2)^4+x(1)^3+x(1)*x(2)*x(3); |
---|
| 3487 | list re=resolve(J); |
---|
| 3488 | list di=intersectionDiv(re); |
---|
| 3489 | di; |
---|
| 3490 | |
---|
| 3491 | } |
---|
| 3492 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 3493 | static proc intersComp(string str1, |
---|
[2e6eac2] | 3494 | string mp1, |
---|
| 3495 | list null1, |
---|
| 3496 | string str2, |
---|
| 3497 | string mp2, |
---|
| 3498 | list null2) |
---|
| 3499 | "Internal procedure - no help and no example available |
---|
| 3500 | " |
---|
| 3501 | { |
---|
| 3502 | //--- format of input |
---|
| 3503 | //--- str1 : ideal (over field extension 1) |
---|
| 3504 | //--- mp1 : minpoly of field extension 1 |
---|
| 3505 | //--- null1: numerical zeros of minpoly |
---|
| 3506 | //--- str2 : ideal (over field extension 2) |
---|
| 3507 | //--- mp2 : minpoly of field extension 2 |
---|
| 3508 | //--- null2: numerical zeros of minpoly |
---|
| 3509 | |
---|
| 3510 | //--- determine intersection matrix of the C-components defined by the input |
---|
| 3511 | |
---|
| 3512 | //--------------------------------------------------------------------------- |
---|
| 3513 | // Initialization |
---|
| 3514 | //--------------------------------------------------------------------------- |
---|
| 3515 | int ii,jj,same; |
---|
| 3516 | def R=basering; |
---|
| 3517 | intmat InterMat[size(null1)][size(null2)]; |
---|
| 3518 | ring ringst=0,(t,s),dp; |
---|
| 3519 | //--------------------------------------------------------------------------- |
---|
| 3520 | // Add new variables s and t and compare the minpolys and ideals |
---|
| 3521 | // to find out whether they are identical |
---|
| 3522 | //--------------------------------------------------------------------------- |
---|
| 3523 | def S=R+ringst; |
---|
| 3524 | setring S; |
---|
| 3525 | if((mp1==mp2)&&(str1==str2)) |
---|
| 3526 | { |
---|
| 3527 | same=1; |
---|
| 3528 | } |
---|
| 3529 | //--- define first Q-component/C-components, substitute t by s |
---|
| 3530 | string tempstr="ideal id1="+str1+";"; |
---|
| 3531 | execute(tempstr); |
---|
| 3532 | execute(mp1); |
---|
| 3533 | id1=subst(id1,t,s); |
---|
| 3534 | poly q=subst(p,t,s); |
---|
| 3535 | kill p; |
---|
| 3536 | //--- define second Q-component/C-components |
---|
| 3537 | tempstr="ideal id2="+str2+";"; |
---|
| 3538 | execute(tempstr); |
---|
| 3539 | execute(mp2); |
---|
| 3540 | //--- do the intersection |
---|
| 3541 | ideal interId=id1+id2+ideal(p)+ideal(q); |
---|
| 3542 | if(same) |
---|
| 3543 | { |
---|
| 3544 | interId=quotient(interId,t-s); |
---|
| 3545 | } |
---|
| 3546 | interId=std(interId); |
---|
| 3547 | //--- refine the comparison by passing to each of the numerical zeros |
---|
| 3548 | //--- of the two minpolys |
---|
[c99fd4] | 3549 | ideal stid=nselect(interId,1..nvars(R)); |
---|
[2e6eac2] | 3550 | ring compl_st=complex,(s,t),dp; |
---|
| 3551 | def stid=imap(S,stid); |
---|
| 3552 | ideal tempid,tempid2; |
---|
| 3553 | for(ii=1;ii<=size(null1);ii++) |
---|
| 3554 | { |
---|
| 3555 | tempstr="number numi="+null1[ii]+";"; |
---|
| 3556 | execute(tempstr); |
---|
| 3557 | tempid=subst(stid,s,numi); |
---|
| 3558 | kill numi; |
---|
| 3559 | for(jj=1;jj<=size(null2);jj++) |
---|
| 3560 | { |
---|
| 3561 | tempstr="number numj="+null2[jj]+";"; |
---|
| 3562 | execute(tempstr); |
---|
| 3563 | tempid2=subst(tempid,t,numj); |
---|
| 3564 | kill numj; |
---|
| 3565 | if(size(tempid2)==0) |
---|
| 3566 | { |
---|
| 3567 | InterMat[ii,jj]=1; |
---|
| 3568 | } |
---|
| 3569 | } |
---|
| 3570 | } |
---|
| 3571 | //--- sanity check; as both Q-components were Q-irreducible, |
---|
| 3572 | //--- summation over all entries of a single row must lead to the same |
---|
| 3573 | //--- result, no matter which row is chosen |
---|
| 3574 | //--- dito for the columns |
---|
| 3575 | int cou,cou1; |
---|
| 3576 | for(ii=1;ii<=ncols(InterMat);ii++) |
---|
| 3577 | { |
---|
| 3578 | cou=0; |
---|
| 3579 | for(jj=1;jj<=nrows(InterMat);jj++) |
---|
| 3580 | { |
---|
| 3581 | cou=cou+InterMat[jj,ii]; |
---|
| 3582 | } |
---|
| 3583 | if(ii==1){cou1=cou;} |
---|
| 3584 | if(cou1!=cou){ERROR("intersComp:matrix has wrong entries");} |
---|
| 3585 | } |
---|
| 3586 | for(ii=1;ii<=nrows(InterMat);ii++) |
---|
| 3587 | { |
---|
| 3588 | cou=0; |
---|
| 3589 | for(jj=1;jj<=ncols(InterMat);jj++) |
---|
| 3590 | { |
---|
| 3591 | cou=cou+InterMat[ii,jj]; |
---|
| 3592 | } |
---|
| 3593 | if(ii==1){cou1=cou;} |
---|
| 3594 | if(cou1!=cou){ERROR("intersComp:matrix has wrong entries");} |
---|
| 3595 | } |
---|
| 3596 | return(InterMat); |
---|
| 3597 | } |
---|
| 3598 | ///////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 3599 | static proc addSelfInter(list re,intmat Inters,list iden,list iden0,intvec endiv) |
---|
[2e6eac2] | 3600 | "Internal procedure - no help and no example available |
---|
| 3601 | " |
---|
| 3602 | { |
---|
| 3603 | //--------------------------------------------------------------------------- |
---|
| 3604 | // Initialization |
---|
| 3605 | //--------------------------------------------------------------------------- |
---|
| 3606 | def R=basering; |
---|
| 3607 | int i,j,k,l,a,b; |
---|
| 3608 | int n=size(iden); |
---|
| 3609 | intvec v,w; |
---|
| 3610 | list satlist; |
---|
| 3611 | def T=re[2][1]; |
---|
| 3612 | setring T; |
---|
| 3613 | poly p; |
---|
| 3614 | p=var(1); //any linear form will do, |
---|
| 3615 | //but this one is most convenient |
---|
| 3616 | ideal F=ideal(p); |
---|
| 3617 | //---------------------------------------------------------------------------- |
---|
| 3618 | // lift linear form to every end ring, determine the multiplicity of |
---|
| 3619 | // the exceptional divisors and store it in Flist |
---|
| 3620 | //---------------------------------------------------------------------------- |
---|
| 3621 | list templist; |
---|
| 3622 | intvec tiv; |
---|
| 3623 | for(i=1;i<=size(endiv);i++) |
---|
| 3624 | { |
---|
| 3625 | if(endiv[i]==1) |
---|
| 3626 | { |
---|
| 3627 | kill v; |
---|
| 3628 | intvec v; |
---|
| 3629 | a=0; |
---|
| 3630 | if(defined(S)) {kill S;} |
---|
| 3631 | def S=re[2][i]; |
---|
| 3632 | setring S; |
---|
| 3633 | map resi=T,BO[5]; |
---|
| 3634 | ideal F=resi(F)+BO[2]; |
---|
| 3635 | ideal Ftemp=F; |
---|
| 3636 | list Flist; |
---|
| 3637 | if(defined(satlist)){kill satlist;} |
---|
| 3638 | list satlist; |
---|
| 3639 | for(a=1;a<=size(dcE);a++) |
---|
| 3640 | { |
---|
| 3641 | for(b=1;b<=size(dcE[a]);b++) |
---|
| 3642 | { |
---|
| 3643 | Ftemp=sat(Ftemp,dcE[a][b][1])[1]; |
---|
| 3644 | } |
---|
| 3645 | } |
---|
| 3646 | F=sat(F,Ftemp)[1]; |
---|
| 3647 | Flist[1]=Ftemp; |
---|
| 3648 | Ftemp=1; |
---|
| 3649 | list pr=primdecGTZ(F); |
---|
| 3650 | v[size(pr)]=0; |
---|
| 3651 | for(j=1;j<=size(pr);j++) |
---|
| 3652 | { |
---|
| 3653 | for(a=1;a<=size(dcE);a++) |
---|
| 3654 | { |
---|
| 3655 | if(j==1) |
---|
| 3656 | { |
---|
| 3657 | kill tiv; |
---|
| 3658 | intvec tiv; |
---|
| 3659 | tiv[size(dcE[a])]=0; |
---|
| 3660 | templist[a]=tiv; |
---|
| 3661 | if(v[j]==1) |
---|
| 3662 | { |
---|
| 3663 | a++; |
---|
| 3664 | continue; |
---|
| 3665 | } |
---|
| 3666 | } |
---|
| 3667 | if(dcE[a][1][2]==0) |
---|
| 3668 | { |
---|
| 3669 | a++; |
---|
| 3670 | continue; |
---|
| 3671 | } |
---|
| 3672 | for(b=1;b<=size(dcE[a]);b++) |
---|
| 3673 | { |
---|
| 3674 | if((size(reduce(dcE[a][b][1],std(pr[j][2])))==0)&& |
---|
| 3675 | (size(reduce(pr[j][2],std(dcE[a][b][1])))==0)) |
---|
| 3676 | { |
---|
| 3677 | templist[a][b]=Vielfachheit(pr[j][1],pr[j][2]); |
---|
| 3678 | v[j]=1; |
---|
| 3679 | break; |
---|
| 3680 | } |
---|
| 3681 | } |
---|
| 3682 | if((v[j]==1)&&(j>1)) break; |
---|
| 3683 | } |
---|
| 3684 | } |
---|
| 3685 | kill v; |
---|
| 3686 | intvec v; |
---|
| 3687 | Flist[2]=templist; |
---|
| 3688 | } |
---|
| 3689 | } |
---|
| 3690 | //----------------------------------------------------------------------------- |
---|
| 3691 | // Now set up all the data: |
---|
| 3692 | // 1. run through all exceptional divisors in iden and determine the |
---|
| 3693 | // coefficients c_i of the divisor of F. ===> civ |
---|
| 3694 | // 2. determine the intersection locus of F^bar and the Ei and from this data |
---|
| 3695 | // the F^bar.Ei . ===> intF |
---|
| 3696 | //----------------------------------------------------------------------------- |
---|
| 3697 | intvec civ; |
---|
| 3698 | intvec intF; |
---|
| 3699 | intF[ncols(Inters)]=0; |
---|
| 3700 | int offset,comPa,ncomp,vd; |
---|
| 3701 | for(i=1;i<=size(iden);i++) |
---|
| 3702 | { |
---|
| 3703 | ncomp=0; |
---|
| 3704 | for(j=1;j<=size(iden[i]);j++) |
---|
| 3705 | { |
---|
| 3706 | if(defined(S)) {kill S;} |
---|
| 3707 | def S=re[2][iden[i][j][1]]; |
---|
| 3708 | setring S; |
---|
| 3709 | if((size(civ)<i+offset+1)&& |
---|
| 3710 | (((Flist[2][iden[i][j][2]][iden[i][j][3]])!=0)||(j==size(iden[i])))) |
---|
| 3711 | { |
---|
| 3712 | ncomp=ncols(dcE[iden[i][j][2]][iden[i][j][3]][4]); |
---|
| 3713 | for(k=1;k<=ncomp;k++) |
---|
| 3714 | { |
---|
| 3715 | civ[i+offset+k]=Flist[2][iden[i][j][2]][iden[i][j][3]]; |
---|
| 3716 | if(deg(std(slocus(dcE[iden[i][j][2]][iden[i][j][3]][1]))[1])>0) |
---|
| 3717 | { |
---|
| 3718 | civ[i+offset+k]=civ[i+k]; |
---|
| 3719 | } |
---|
| 3720 | } |
---|
| 3721 | } |
---|
| 3722 | if(defined(interId)) {kill interId;} |
---|
| 3723 | ideal interId=dcE[iden[i][j][2]][iden[i][j][3]][1]+Flist[1]; |
---|
| 3724 | if(defined(interList)) {kill interList;} |
---|
| 3725 | list interList; |
---|
| 3726 | interList[1]=string(interId); |
---|
| 3727 | interList[2]=ideal(0); |
---|
| 3728 | export(interList); |
---|
| 3729 | if(defined(doneId)) {kill doneId;} |
---|
| 3730 | if(defined(tempId)) {kill tempId;} |
---|
| 3731 | ideal doneId=ideal(1); |
---|
| 3732 | if(defined(dl)) {kill dl;} |
---|
| 3733 | list dl; |
---|
| 3734 | for(k=1;k<j;k++) |
---|
| 3735 | { |
---|
| 3736 | if(defined(St)) {kill St;} |
---|
| 3737 | def St=re[2][iden[i][k][1]]; |
---|
| 3738 | setring St; |
---|
| 3739 | if(defined(str)){kill str;} |
---|
| 3740 | string str="interId="+interList[1]+";"; |
---|
| 3741 | execute(str); |
---|
| 3742 | if(deg(std(interId)[1])==0) |
---|
| 3743 | { |
---|
| 3744 | setring S; |
---|
| 3745 | k++; |
---|
| 3746 | continue; |
---|
| 3747 | } |
---|
| 3748 | setring S; |
---|
| 3749 | if(defined(opath)) {kill opath;} |
---|
| 3750 | def opath=imap(re[2][iden[i][k][1]],path); |
---|
| 3751 | comPa=1; |
---|
| 3752 | while(opath[1,comPa]==path[1,comPa]) |
---|
| 3753 | { |
---|
| 3754 | comPa++; |
---|
| 3755 | if((comPa>ncols(path))||(comPa>ncols(opath))) break; |
---|
| 3756 | } |
---|
| 3757 | comPa=int(leadcoef(path[1,comPa-1])); |
---|
| 3758 | if(defined(str)) {kill str;} |
---|
| 3759 | string str="interList"; |
---|
| 3760 | attrib(str,"algext","poly p=t-1;"); |
---|
| 3761 | dl=fetchInTree(re,iden[i][k][1],comPa,iden[i][j][1],str,iden0,1); |
---|
| 3762 | if(defined(tempId)){kill tempId;} |
---|
| 3763 | str="ideal tempId="+dl[1]+";"; |
---|
| 3764 | execute(str); |
---|
| 3765 | doneId=intersect(doneId,tempId); |
---|
| 3766 | str="interId="+interList[1]+";"; |
---|
| 3767 | execute(str); |
---|
| 3768 | interId=sat(interId,doneId)[1]; |
---|
| 3769 | interList[1]=string(interId); |
---|
| 3770 | } |
---|
| 3771 | interId=std(interId); |
---|
| 3772 | if(dim(interId)>0) |
---|
| 3773 | { |
---|
| 3774 | "oops, intersection not a set of points"; |
---|
| 3775 | ~; |
---|
| 3776 | } |
---|
| 3777 | vd=vdim(interId); |
---|
| 3778 | if(vd>0) |
---|
| 3779 | { |
---|
| 3780 | for(k=i+offset;k<=i+offset+ncomp-1;k++) |
---|
| 3781 | { |
---|
[828fab] | 3782 | intF[k]=intF[k]+(vd div ncomp); |
---|
[2e6eac2] | 3783 | } |
---|
| 3784 | } |
---|
| 3785 | } |
---|
| 3786 | offset=size(civ)-i-1; |
---|
| 3787 | } |
---|
| 3788 | if(defined(tiv)){kill tiv;} |
---|
| 3789 | intvec tiv=civ[2..size(civ)]; |
---|
| 3790 | civ=tiv; |
---|
| 3791 | kill tiv; |
---|
| 3792 | //----------------------------------------------------------------------------- |
---|
| 3793 | // Using the F_total= sum c_i Ei + F^bar, the intersection matrix Inters and |
---|
| 3794 | // the f^bar.Ei, determine the selfintersection numbers of the Ei from the |
---|
| 3795 | // equation F_total.Ei=0 and store it in the diagonal of Inters. |
---|
| 3796 | //----------------------------------------------------------------------------- |
---|
| 3797 | intvec diag=Inters*civ+intF; |
---|
| 3798 | for(i=1;i<=size(diag);i++) |
---|
| 3799 | { |
---|
[d44974d] | 3800 | Inters[i,i]=-diag[i] div civ[i]; |
---|
[2e6eac2] | 3801 | } |
---|
| 3802 | return(Inters); |
---|
| 3803 | } |
---|
| 3804 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 3805 | static proc invSort(list re, list #) |
---|
[2e6eac2] | 3806 | "Internal procedure - no help and no example available |
---|
| 3807 | " |
---|
| 3808 | { |
---|
| 3809 | int i,j,k,markier,EZeiger,offset; |
---|
| 3810 | intvec v,e; |
---|
| 3811 | intvec deleted; |
---|
| 3812 | if(size(#)>0) |
---|
| 3813 | { |
---|
| 3814 | deleted=#[1]; |
---|
| 3815 | } |
---|
| 3816 | else |
---|
| 3817 | { |
---|
| 3818 | deleted[size(re[2])]=0; |
---|
| 3819 | } |
---|
| 3820 | list LE,HI; |
---|
| 3821 | def R=basering; |
---|
| 3822 | //---------------------------------------------------------------------------- |
---|
| 3823 | // Go through all rings |
---|
| 3824 | //---------------------------------------------------------------------------- |
---|
| 3825 | for(i=1;i<=size(re[2]);i++) |
---|
| 3826 | { |
---|
| 3827 | if(deleted[i]){i++;continue} |
---|
| 3828 | def S=re[2][i]; |
---|
| 3829 | setring S; |
---|
| 3830 | //---------------------------------------------------------------------------- |
---|
| 3831 | // Determine Invariant |
---|
| 3832 | //---------------------------------------------------------------------------- |
---|
| 3833 | if((size(BO[3])==size(BO[9]))||(size(BO[3])==size(BO[9])+1)) |
---|
| 3834 | { |
---|
| 3835 | if(defined(merk2)){kill merk2;} |
---|
| 3836 | intvec merk2; |
---|
| 3837 | EZeiger=0; |
---|
| 3838 | for(j=1;j<=size(BO[9]);j++) |
---|
| 3839 | { |
---|
| 3840 | offset=0; |
---|
| 3841 | if(BO[7][j]==-1) |
---|
| 3842 | { |
---|
| 3843 | BO[7][j]=size(BO[4])-EZeiger; |
---|
| 3844 | } |
---|
| 3845 | for(k=EZeiger+1;(k<=EZeiger+BO[7][j])&&(k<=size(BO[4]));k++) |
---|
| 3846 | { |
---|
| 3847 | if(BO[6][k]==2) |
---|
| 3848 | { |
---|
| 3849 | offset++; |
---|
| 3850 | } |
---|
| 3851 | } |
---|
| 3852 | EZeiger=EZeiger+BO[7][1]; |
---|
| 3853 | merk2[3*j-2]=BO[3][j]; |
---|
| 3854 | merk2[3*j-1]=BO[9][j]-offset; |
---|
| 3855 | if(size(invSat[2])>j) |
---|
| 3856 | { |
---|
| 3857 | merk2[3*j]=-invSat[2][j]; |
---|
| 3858 | } |
---|
| 3859 | else |
---|
| 3860 | { |
---|
| 3861 | if(j<size(BO[9])) |
---|
| 3862 | { |
---|
| 3863 | "!!!!!problem with invSat";~; |
---|
| 3864 | } |
---|
| 3865 | } |
---|
| 3866 | } |
---|
| 3867 | if((size(BO[3])>size(BO[9]))) |
---|
| 3868 | { |
---|
| 3869 | merk2[size(merk2)+1]=BO[3][size(BO[3])]; |
---|
| 3870 | } |
---|
| 3871 | if((size(merk2)%3)==0) |
---|
| 3872 | { |
---|
| 3873 | intvec tintvec=merk2[1..size(merk2)-1]; |
---|
| 3874 | merk2=tintvec; |
---|
| 3875 | kill tintvec; |
---|
| 3876 | } |
---|
| 3877 | } |
---|
| 3878 | else |
---|
| 3879 | { |
---|
| 3880 | ERROR("This situation should not occur, please send the example |
---|
| 3881 | to the authors."); |
---|
| 3882 | } |
---|
| 3883 | //---------------------------------------------------------------------------- |
---|
| 3884 | // Save invariant describing current center as an object in this ring |
---|
| 3885 | // We also store information on the intersection with the center and the |
---|
| 3886 | // exceptional divisors |
---|
| 3887 | //---------------------------------------------------------------------------- |
---|
| 3888 | cent=std(cent); |
---|
| 3889 | kill e; |
---|
| 3890 | intvec e; |
---|
| 3891 | for(j=1;j<=size(BO[4]);j++) |
---|
| 3892 | { |
---|
| 3893 | if(size(reduce(BO[4][j],std(cent+BO[1])))==0) |
---|
| 3894 | { |
---|
| 3895 | e[j]=1; |
---|
| 3896 | } |
---|
| 3897 | else |
---|
| 3898 | { |
---|
| 3899 | e[j]=0; |
---|
| 3900 | } |
---|
| 3901 | } |
---|
| 3902 | if(size(ideal(merk2))==0) |
---|
| 3903 | { |
---|
| 3904 | markier=1; |
---|
| 3905 | } |
---|
| 3906 | if((size(merk2)%3==0)&&(merk2[size(merk2)]==0)) |
---|
| 3907 | { |
---|
| 3908 | intvec blabla=merk2[1..size(merk2)-1]; |
---|
| 3909 | merk2=blabla; |
---|
| 3910 | kill blabla; |
---|
| 3911 | } |
---|
| 3912 | if(defined(invCenter)){kill invCenter;} |
---|
| 3913 | list invCenter=cent,merk2,e; |
---|
| 3914 | export invCenter; |
---|
| 3915 | //---------------------------------------------------------------------------- |
---|
| 3916 | // Insert it into correct place in the list |
---|
| 3917 | //---------------------------------------------------------------------------- |
---|
| 3918 | if(i==1) |
---|
| 3919 | { |
---|
| 3920 | if(!markier) |
---|
| 3921 | { |
---|
| 3922 | HI=intvec(merk2[1]+1),intvec(1); |
---|
| 3923 | } |
---|
| 3924 | else |
---|
| 3925 | { |
---|
| 3926 | HI=intvec(778),intvec(1); // some really large integer |
---|
| 3927 | // will be changed at the end!!! |
---|
| 3928 | } |
---|
| 3929 | LE[1]=HI; |
---|
| 3930 | i++; |
---|
| 3931 | setring R; |
---|
| 3932 | kill S; |
---|
| 3933 | continue; |
---|
| 3934 | } |
---|
| 3935 | if(markier==1) |
---|
| 3936 | { |
---|
| 3937 | if(i==2) |
---|
| 3938 | { |
---|
| 3939 | HI=intvec(777),intvec(2); // same really large integer-1 |
---|
| 3940 | LE[2]=HI; |
---|
| 3941 | i++; |
---|
| 3942 | setring R; |
---|
| 3943 | kill S; |
---|
| 3944 | continue; |
---|
| 3945 | } |
---|
| 3946 | else |
---|
| 3947 | { |
---|
| 3948 | if(ncols(path)==2) |
---|
| 3949 | { |
---|
| 3950 | LE[2][2][size(LE[2][2])+1]=i; |
---|
| 3951 | i++; |
---|
| 3952 | setring R; |
---|
| 3953 | kill S; |
---|
| 3954 | continue; |
---|
| 3955 | } |
---|
| 3956 | else |
---|
| 3957 | { |
---|
| 3958 | markier=0; |
---|
| 3959 | } |
---|
| 3960 | } |
---|
| 3961 | } |
---|
| 3962 | j=1; |
---|
| 3963 | def SOld=re[2][int(leadcoef(path[1,ncols(path)]))]; |
---|
| 3964 | setring SOld; |
---|
| 3965 | merk2=invCenter[2]; |
---|
| 3966 | setring S; |
---|
| 3967 | kill SOld; |
---|
| 3968 | while(merk2<LE[j][1]) |
---|
| 3969 | { |
---|
| 3970 | j++; |
---|
| 3971 | if(j>size(LE)) break; |
---|
| 3972 | } |
---|
| 3973 | HI=merk2,intvec(i); |
---|
| 3974 | if(j<=size(LE)) |
---|
| 3975 | { |
---|
| 3976 | if(merk2>LE[j][1]) |
---|
| 3977 | { |
---|
| 3978 | LE=insert(LE,HI,j-1); |
---|
| 3979 | } |
---|
| 3980 | else |
---|
| 3981 | { |
---|
| 3982 | while((merk2==LE[j][1])&&(size(merk2)<size(LE[j][1]))) |
---|
| 3983 | { |
---|
| 3984 | j++; |
---|
| 3985 | if(j>size(LE)) break; |
---|
| 3986 | } |
---|
| 3987 | if(j<=size(LE)) |
---|
| 3988 | { |
---|
| 3989 | if((merk2!=LE[j][1])||(size(merk2)!=size(LE[j][1]))) |
---|
| 3990 | { |
---|
| 3991 | LE=insert(LE,HI,j-1); |
---|
| 3992 | } |
---|
| 3993 | else |
---|
| 3994 | { |
---|
| 3995 | LE[j][2][size(LE[j][2])+1]=i; |
---|
| 3996 | } |
---|
| 3997 | } |
---|
| 3998 | else |
---|
| 3999 | { |
---|
| 4000 | LE[size(LE)+1]=HI; |
---|
| 4001 | } |
---|
| 4002 | } |
---|
| 4003 | } |
---|
| 4004 | else |
---|
| 4005 | { |
---|
| 4006 | LE[size(LE)+1]=HI; |
---|
| 4007 | } |
---|
| 4008 | setring R; |
---|
| 4009 | kill S; |
---|
| 4010 | } |
---|
| 4011 | if((LE[1][1]==intvec(778)) && (size(LE)>2)) |
---|
| 4012 | { |
---|
| 4013 | LE[1][1]=intvec(LE[3][1][1]+2); // by now we know what 'sufficiently |
---|
| 4014 | LE[2][1]=intvec(LE[3][1][1]+1); // large' is |
---|
| 4015 | } |
---|
| 4016 | return(LE); |
---|
| 4017 | } |
---|
| 4018 | example |
---|
| 4019 | {"EXAMPLE:"; |
---|
| 4020 | echo = 2; |
---|
| 4021 | ring r = 0,(x(1..3)),dp(3); |
---|
| 4022 | ideal J=x(1)^3-x(1)*x(2)^3+x(3)^2; |
---|
| 4023 | list re=resolve(J,1); |
---|
| 4024 | list di=invSort(re); |
---|
| 4025 | di; |
---|
| 4026 | } |
---|
| 4027 | ///////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 4028 | static proc addToRE(intvec v,int x,list RE) |
---|
[2e6eac2] | 4029 | "Internal procedure - no help and no example available |
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| 4030 | " |
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| 4031 | { |
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| 4032 | //--- auxilliary procedure for collectDiv, |
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| 4033 | //--- inserting an entry at the correct place |
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| 4034 | int i=1; |
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| 4035 | while(i<=size(RE)) |
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| 4036 | { |
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| 4037 | if(v==RE[i][1]) |
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| 4038 | { |
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| 4039 | RE[i][2][size(RE[i][2])+1]=x; |
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| 4040 | return(RE); |
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| 4041 | } |
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| 4042 | if(v>RE[i][1]) |
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| 4043 | { |
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| 4044 | list templist=v,intvec(x); |
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| 4045 | RE=insert(RE,templist,i-1); |
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| 4046 | return(RE); |
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| 4047 | } |
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| 4048 | i++; |
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| 4049 | } |
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| 4050 | list templist=v,intvec(x); |
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| 4051 | RE=insert(RE,templist,size(RE)); |
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| 4052 | return(RE); |
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| 4053 | } |
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| 4054 | //////////////////////////////////////////////////////////////////////////// |
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| 4055 | |
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| 4056 | proc collectDiv(list re,list #) |
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| 4057 | "USAGE: collectDiv(L); |
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| 4058 | @* L = list of rings |
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| 4059 | ASSUME: L is output of resolution of singularities |
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| 4060 | COMPUTE: list representing the identification of the exceptional divisors |
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| 4061 | in the various charts |
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| 4062 | RETURN: list l, where |
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| 4063 | l[1]: intmat, entry k in position i,j implies BO[4][j] of chart i |
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| 4064 | is divisor k (if k!=0) |
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| 4065 | if k==0, no divisor corresponding to i,j |
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| 4066 | l[2]: list ll, where each entry of ll is a list of intvecs |
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[2cd0ca] | 4067 | entry i,j in list ll[k] implies BO[4][j] of chart i |
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| 4068 | is divisor k |
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[2e6eac2] | 4069 | l[3]: list L |
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| 4070 | EXAMPLE: example collectDiv; shows an example |
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| 4071 | " |
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| 4072 | { |
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| 4073 | //------------------------------------------------------------------------ |
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| 4074 | // Initialization |
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| 4075 | //------------------------------------------------------------------------ |
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| 4076 | int i,j,k,l,m,maxk,maxj,mPa,oPa,interC,pa,ignoreL,iTotal; |
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| 4077 | int mLast,oLast=1,1; |
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| 4078 | intvec deleted; |
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| 4079 | //--- sort the rings by the invariant which controlled the last of the |
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| 4080 | //--- exceptional divisors |
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| 4081 | if(size(#)>0) |
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| 4082 | { |
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| 4083 | deleted=#[1]; |
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| 4084 | } |
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| 4085 | else |
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| 4086 | { |
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| 4087 | deleted[size(re[2])]=0; |
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| 4088 | } |
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| 4089 | list LE=invSort(re,deleted); |
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| 4090 | list LEtotal=LE; |
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| 4091 | intmat M[size(re[2])][size(re[2])]; |
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| 4092 | intvec invar,tempiv; |
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| 4093 | def R=basering; |
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| 4094 | list divList; |
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| 4095 | list RE,SE; |
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| 4096 | intvec myEi,otherEi,tempe; |
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| 4097 | int co=2; |
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| 4098 | |
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| 4099 | while(size(LE)>0) |
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| 4100 | { |
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| 4101 | //------------------------------------------------------------------------ |
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| 4102 | // Run through the sorted list LE whose entries are lists containing |
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| 4103 | // the invariant and the numbers of all rings corresponding to it |
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| 4104 | //------------------------------------------------------------------------ |
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| 4105 | for(i=co;i<=size(LE);i++) |
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| 4106 | { |
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| 4107 | //--- i==1 in first iteration: |
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| 4108 | //--- the original ring which did not arise from a blow-up |
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| 4109 | //--- hence there are no exceptional divisors to be identified there ; |
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| 4110 | |
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| 4111 | //------------------------------------------------------------------------ |
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| 4112 | // For each fixed value of the invariant, run through all corresponding |
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| 4113 | // rings |
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| 4114 | //------------------------------------------------------------------------ |
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| 4115 | for(l=1;l<=size(LE[i][2]);l++) |
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| 4116 | { |
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| 4117 | if(defined(S)){kill S;} |
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| 4118 | def S=re[2][LE[i][2][l]]; |
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| 4119 | setring S; |
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| 4120 | if(size(BO[4])>maxj){maxj=size(BO[4]);} |
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| 4121 | //--- all exceptional divisors, except the last one, were previously |
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| 4122 | //--- identified - hence we can simply inherit the data from the parent ring |
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| 4123 | for(j=1;j<size(BO[4]);j++) |
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| 4124 | { |
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| 4125 | if(deg(std(BO[4][j])[1])>0) |
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| 4126 | { |
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| 4127 | k=int(leadcoef(path[1,ncols(path)])); |
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| 4128 | k=M[k,j]; |
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| 4129 | if(k==0) |
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| 4130 | { |
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| 4131 | RE=addToRE(LE[i][1],LE[i][2][l],RE); |
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| 4132 | ignoreL=1; |
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| 4133 | break; |
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| 4134 | } |
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| 4135 | M[LE[i][2][l],j]=k; |
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| 4136 | tempiv=LE[i][2][l],j; |
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| 4137 | divList[k][size(divList[k])+1]=tempiv; |
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| 4138 | } |
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| 4139 | } |
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| 4140 | if(ignoreL){ignoreL=0;l++;continue;} |
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| 4141 | //---------------------------------------------------------------------------- |
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| 4142 | // In the remaining part of the procedure, the identification of the last |
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| 4143 | // exceptional divisor takes place. |
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| 4144 | // Step 1: check whether there is a previously considered ring with the |
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| 4145 | // same parent; if this is the case, we can again inherit the data |
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| 4146 | // Step 1':check whether the parent had a stored center which it then used |
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| 4147 | // in this case, we are dealing with an additional component of this |
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| 4148 | // divisor: store it in the integer otherComp |
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| 4149 | // Step 2: if no appropriate ring was found in step 1, we check whether |
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| 4150 | // there is a previously considered ring, in the parent of which |
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| 4151 | // the center intersects the same exceptional divisors as the center |
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| 4152 | // in our parent. |
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| 4153 | // if such a ring does not exist: new exceptional divisor |
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| 4154 | // if it exists: see below |
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| 4155 | //---------------------------------------------------------------------------- |
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| 4156 | if(path[1,ncols(path)-1]==0) |
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| 4157 | { |
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| 4158 | //--- current ring originated from very first blow-up |
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| 4159 | //--- hence exceptional divisor is the first one |
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| 4160 | M[LE[i][2][l],1]=1; |
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| 4161 | if(size(divList)>0) |
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| 4162 | { |
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| 4163 | divList[1][size(divList[1])+1]=intvec(LE[i][2][l],j); |
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| 4164 | } |
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| 4165 | else |
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| 4166 | { |
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| 4167 | divList[1]=list(intvec(LE[i][2][l],j)); |
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| 4168 | } |
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| 4169 | l++; |
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| 4170 | continue; |
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| 4171 | } |
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| 4172 | if(l==1) |
---|
| 4173 | { |
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| 4174 | list TE=addToRE(LE[i][1],1,SE); |
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| 4175 | if(size(TE)!=size(SE)) |
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| 4176 | { |
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| 4177 | //--- new value of invariant hence new exceptional divisor |
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| 4178 | SE=TE; |
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| 4179 | divList[size(divList)+1]=list(intvec(LE[i][2][l],j)); |
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| 4180 | M[LE[i][2][l],j]=size(divList); |
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| 4181 | } |
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| 4182 | kill TE; |
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| 4183 | } |
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| 4184 | for(k=1;k<=size(LEtotal);k++) |
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| 4185 | { |
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| 4186 | if(LE[i][1]==LEtotal[k][1]) |
---|
| 4187 | { |
---|
| 4188 | iTotal=k; |
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| 4189 | break; |
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| 4190 | } |
---|
| 4191 | } |
---|
| 4192 | //--- Step 1 |
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| 4193 | k=1; |
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| 4194 | while(LEtotal[iTotal][2][k]<LE[i][2][l]) |
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| 4195 | { |
---|
| 4196 | if(defined(tempPath)){kill tempPath;} |
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| 4197 | def tempPath=imap(re[2][LEtotal[iTotal][2][k]],path); |
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| 4198 | if(tempPath[1,ncols(tempPath)]==path[1,ncols(path)]) |
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| 4199 | { |
---|
| 4200 | //--- Same parent, hence we inherit our data |
---|
| 4201 | m=size(imap(re[2][LEtotal[iTotal][2][k]],BO)[4]); |
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| 4202 | m=M[LEtotal[iTotal][2][k],m]; |
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| 4203 | if(m==0) |
---|
| 4204 | { |
---|
| 4205 | RE=addToRE(LE[i][1],LE[i][2][l],RE); |
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| 4206 | ignoreL=1; |
---|
| 4207 | break; |
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| 4208 | } |
---|
| 4209 | M[LE[i][2][l],j]=m; |
---|
| 4210 | tempiv=LE[i][2][l],j; |
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| 4211 | divList[m][size(divList[m])+1]=tempiv; |
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| 4212 | break; |
---|
| 4213 | } |
---|
| 4214 | k++; |
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| 4215 | if(k>size(LEtotal[iTotal][2])) {break;} |
---|
| 4216 | } |
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| 4217 | if(ignoreL){ignoreL=0;l++;continue;} |
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| 4218 | //--- Step 1', if necessary |
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| 4219 | if(M[LE[i][2][l],j]==0) |
---|
| 4220 | { |
---|
| 4221 | int savedCent; |
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| 4222 | def SPa1=re[2][int(leadcoef(path[1,ncols(path)]))]; |
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| 4223 | // parent ring |
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| 4224 | setring SPa1; |
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| 4225 | if(size(BO)>9) |
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| 4226 | { |
---|
| 4227 | if(size(BO[10])>0) |
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| 4228 | { |
---|
| 4229 | savedCent=1; |
---|
| 4230 | } |
---|
| 4231 | } |
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| 4232 | if(!savedCent) |
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| 4233 | { |
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| 4234 | def SPa2=re[2][int(leadcoef(path[1,ncols(path)]))]; |
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| 4235 | map lMa=SPa2,lastMap; |
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| 4236 | // map leading from grandparent to parent |
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| 4237 | list transBO=lMa(BO); |
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| 4238 | // actually we only need BO[10], but this is an |
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| 4239 | // object not a name |
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| 4240 | list tempsat; |
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| 4241 | if(size(transBO)>9) |
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| 4242 | { |
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| 4243 | //--- there were saved centers |
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| 4244 | while((k<=size(transBO[10])) & (savedCent==0)) |
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| 4245 | { |
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| 4246 | tempsat=sat(transBO[10][k][1],BO[4][size(BO[4])]); |
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| 4247 | if(deg(tempsat[1][1])!=0) |
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| 4248 | { |
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| 4249 | //--- saved center can be seen in this affine chart |
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| 4250 | if((size(reduce(tempsat[1],std(cent)))==0) && |
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| 4251 | (size(reduce(cent,tempsat[1]))==0)) |
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| 4252 | { |
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| 4253 | //--- this was the saved center which was used |
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| 4254 | savedCent=1; |
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| 4255 | } |
---|
| 4256 | } |
---|
| 4257 | k++; |
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| 4258 | } |
---|
| 4259 | } |
---|
| 4260 | kill lMa; // clean up temporary objects |
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| 4261 | kill tempsat; |
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| 4262 | kill transBO; |
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| 4263 | } |
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| 4264 | setring S; // back to the ring which we want to consider |
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| 4265 | if(savedCent==1) |
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| 4266 | { |
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| 4267 | vector otherComp; |
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| 4268 | otherComp[M[int(leadcoef(path[1,ncols(path)])),size(BO[4])-1]] |
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| 4269 | =1; |
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| 4270 | } |
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| 4271 | kill savedCent; |
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| 4272 | if (defined(SPa2)){kill SPa2;} |
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| 4273 | kill SPa1; |
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| 4274 | } |
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| 4275 | //--- Step 2, if necessary |
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| 4276 | if(M[LE[i][2][l],j]==0) |
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| 4277 | { |
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| 4278 | //--- we are not done after step 1 and 2 |
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| 4279 | pa=int(leadcoef(path[1,ncols(path)])); // parent ring |
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| 4280 | tempe=imap(re[2][pa],invCenter)[3]; // intersection there |
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| 4281 | kill myEi; |
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| 4282 | intvec myEi; |
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| 4283 | for(k=1;k<=size(tempe);k++) |
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| 4284 | { |
---|
| 4285 | if(tempe[k]==1) |
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| 4286 | { |
---|
| 4287 | //--- center meets this exceptional divisor |
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| 4288 | myEi[size(myEi)+1]=M[pa,k]; |
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| 4289 | mLast=k; |
---|
| 4290 | } |
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| 4291 | } |
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| 4292 | //--- ring in which the last divisor we meet is new-born |
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| 4293 | mPa=int(leadcoef(path[1,mLast+2])); |
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| 4294 | k=1; |
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| 4295 | while(LEtotal[iTotal][2][k]<LE[i][2][l]) |
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| 4296 | { |
---|
| 4297 | //--- perform the same preparations for the ring we want to compare with |
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| 4298 | if(defined(tempPath)){kill tempPath;} |
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| 4299 | def tempPath=imap(re[2][LEtotal[iTotal][2][k]],path); |
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| 4300 | // its ancestors |
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| 4301 | tempe=imap(re[2][int(leadcoef(tempPath[1,ncols(tempPath)]))], |
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| 4302 | invCenter)[3]; // its intersections |
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| 4303 | kill otherEi; |
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| 4304 | intvec otherEi; |
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| 4305 | for(m=1;m<=size(tempe);m++) |
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| 4306 | { |
---|
| 4307 | if(tempe[m]==1) |
---|
| 4308 | { |
---|
| 4309 | //--- its center meets this exceptional divisor |
---|
| 4310 | otherEi[size(otherEi)+1] |
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| 4311 | =M[int(leadcoef(tempPath[1,ncols(tempPath)])),m]; |
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| 4312 | oLast=m; |
---|
| 4313 | } |
---|
| 4314 | } |
---|
| 4315 | if(myEi!=otherEi) |
---|
| 4316 | { |
---|
| 4317 | //--- not the same center because of intersection properties with the |
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| 4318 | //--- exceptional divisor |
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| 4319 | k++; |
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| 4320 | if(k>size(LEtotal[iTotal][2])) |
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| 4321 | { |
---|
| 4322 | break; |
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| 4323 | } |
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| 4324 | else |
---|
| 4325 | { |
---|
| 4326 | continue; |
---|
| 4327 | } |
---|
| 4328 | } |
---|
| 4329 | //---------------------------------------------------------------------------- |
---|
| 4330 | // Current situation: |
---|
| 4331 | // 1. the last exceptional divisor could not be identified by simply |
---|
| 4332 | // considering its parent |
---|
| 4333 | // 2. it could not be proved to be a new one by considering its intersections |
---|
| 4334 | // with previous exceptional divisors |
---|
| 4335 | //---------------------------------------------------------------------------- |
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| 4336 | if(defined(bool1)) { kill bool1;} |
---|
| 4337 | int bool1= |
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| 4338 | compareE(re,LE[i][2][l],LEtotal[iTotal][2][k],divList); |
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| 4339 | if(bool1) |
---|
| 4340 | { |
---|
| 4341 | //--- found some non-empty intersection |
---|
| 4342 | if(bool1==1) |
---|
| 4343 | { |
---|
| 4344 | //--- it is really the same exceptional divisor |
---|
| 4345 | m=size(imap(re[2][LEtotal[iTotal][2][k]],BO)[4]); |
---|
| 4346 | m=M[LEtotal[iTotal][2][k],m]; |
---|
| 4347 | if(m==0) |
---|
| 4348 | { |
---|
| 4349 | RE=addToRE(LE[i][1],LE[i][2][l],RE); |
---|
| 4350 | ignoreL=1; |
---|
| 4351 | break; |
---|
| 4352 | } |
---|
| 4353 | M[LE[i][2][l],j]=m; |
---|
| 4354 | tempiv=LE[i][2][l],j; |
---|
| 4355 | divList[m][size(divList[m])+1]=tempiv; |
---|
| 4356 | break; |
---|
| 4357 | } |
---|
| 4358 | else |
---|
| 4359 | { |
---|
| 4360 | m=size(imap(re[2][LEtotal[iTotal][2][k]],BO)[4]); |
---|
| 4361 | m=M[LEtotal[iTotal][2][k],m]; |
---|
| 4362 | if(m!=0) |
---|
| 4363 | { |
---|
| 4364 | otherComp[m]=1; |
---|
| 4365 | } |
---|
| 4366 | } |
---|
| 4367 | } |
---|
| 4368 | k++; |
---|
| 4369 | if(k>size(LEtotal[iTotal][2])) |
---|
| 4370 | { |
---|
| 4371 | break; |
---|
| 4372 | } |
---|
| 4373 | } |
---|
| 4374 | if(ignoreL){ignoreL=0;l++;continue;} |
---|
| 4375 | if( M[LE[i][2][l],j]==0) |
---|
| 4376 | { |
---|
| 4377 | divList[size(divList)+1]=list(intvec(LE[i][2][l],j)); |
---|
| 4378 | M[LE[i][2][l],j]=size(divList); |
---|
| 4379 | } |
---|
| 4380 | } |
---|
| 4381 | setring R; |
---|
| 4382 | kill S; |
---|
| 4383 | } |
---|
| 4384 | } |
---|
| 4385 | LE=RE; |
---|
| 4386 | co=1; |
---|
| 4387 | kill RE; |
---|
| 4388 | list RE; |
---|
| 4389 | } |
---|
| 4390 | //---------------------------------------------------------------------------- |
---|
| 4391 | // Add the strict transform to the list of divisors at the last place |
---|
| 4392 | // and clean up M |
---|
| 4393 | //---------------------------------------------------------------------------- |
---|
| 4394 | //--- add strict transform |
---|
| 4395 | for(i=1;i<=size(re[2]);i++) |
---|
| 4396 | { |
---|
| 4397 | if(defined(S)){kill S;} |
---|
| 4398 | def S=re[2][i]; |
---|
| 4399 | setring S; |
---|
| 4400 | if(size(reduce(cent,std(BO[2])))==0) |
---|
| 4401 | { |
---|
| 4402 | tempiv=i,0; |
---|
| 4403 | RE[size(RE)+1]=tempiv; |
---|
| 4404 | } |
---|
| 4405 | setring R; |
---|
| 4406 | } |
---|
| 4407 | divList[size(divList)+1]=RE; |
---|
| 4408 | //--- drop trailing zero-columns of M |
---|
| 4409 | intvec iv0; |
---|
| 4410 | iv0[nrows(M)]=0; |
---|
| 4411 | for(i=ncols(M);i>0;i--) |
---|
| 4412 | { |
---|
| 4413 | if(intvec(M[1..nrows(M),i])!=iv0) break; |
---|
| 4414 | } |
---|
| 4415 | intmat N[nrows(M)][i]; |
---|
| 4416 | for(i=1;i<=ncols(N);i++) |
---|
| 4417 | { |
---|
| 4418 | N[1..nrows(M),i]=M[1..nrows(M),i]; |
---|
| 4419 | } |
---|
| 4420 | kill M; |
---|
| 4421 | intmat M=N; |
---|
| 4422 | list retlist=cleanUpDiv(re,M,divList); |
---|
| 4423 | return(retlist); |
---|
| 4424 | } |
---|
| 4425 | example |
---|
| 4426 | {"EXAMPLE:"; |
---|
| 4427 | echo = 2; |
---|
| 4428 | ring R=0,(x,y,z),dp; |
---|
| 4429 | ideal I=xyz+x4+y4+z4; |
---|
| 4430 | //we really need to blow up curves even if the generic point of |
---|
| 4431 | //the curve the total transform is n.c. |
---|
| 4432 | //this occurs here in r[2][5] |
---|
[471d0cf] | 4433 | list re=resolve(I); |
---|
[2e6eac2] | 4434 | list di=collectDiv(re); |
---|
[471d0cf] | 4435 | di[1]; |
---|
| 4436 | di[2]; |
---|
[2e6eac2] | 4437 | } |
---|
| 4438 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 4439 | static proc cleanUpDiv(list re,intmat M,list divList) |
---|
[2e6eac2] | 4440 | "Internal procedure - no help and no example available |
---|
| 4441 | " |
---|
| 4442 | { |
---|
| 4443 | //--- It may occur that two different entries of invSort coincide on the |
---|
| 4444 | //--- first part up to the last entry of the shorter one. In this case |
---|
| 4445 | //--- exceptional divisors may appear in both entries of the invSort-list. |
---|
| 4446 | //--- To correct this, we now compare the final collection of Divisors |
---|
| 4447 | //--- for coinciding ones. |
---|
| 4448 | int i,j,k,a,oPa,mPa,comPa,mdim,odim; |
---|
| 4449 | def R=basering; |
---|
| 4450 | for(i=1;i<=size(divList)-2;i++) |
---|
| 4451 | { |
---|
| 4452 | if(defined(Sm)){kill Sm;} |
---|
| 4453 | def Sm=re[2][divList[i][1][1]]; |
---|
| 4454 | setring Sm; |
---|
| 4455 | mPa=int(leadcoef(path[1,ncols(path)])); |
---|
| 4456 | if(defined(SmPa)){kill SmPa;} |
---|
| 4457 | def SmPa=re[2][mPa]; |
---|
| 4458 | setring SmPa; |
---|
| 4459 | mdim=dim(std(BO[1]+cent)); |
---|
| 4460 | setring Sm; |
---|
| 4461 | if(mPa==1) |
---|
| 4462 | { |
---|
| 4463 | //--- very first divisor originates exactly from the first blow-up |
---|
| 4464 | //--- there cannot be any mistake here |
---|
| 4465 | i++; |
---|
| 4466 | continue; |
---|
| 4467 | } |
---|
| 4468 | for(j=i+1;j<=size(divList)-1;j++) |
---|
| 4469 | { |
---|
| 4470 | setring Sm; |
---|
| 4471 | for(k=1;k<=size(divList[j]);k++) |
---|
| 4472 | { |
---|
| 4473 | if(size(findInIVList(1,divList[j][k][1],divList[i]))>1) |
---|
| 4474 | { |
---|
| 4475 | //--- same divisor cannot appear twice in the same chart |
---|
| 4476 | k=-1; |
---|
| 4477 | break; |
---|
| 4478 | } |
---|
| 4479 | } |
---|
| 4480 | if(k==-1) |
---|
| 4481 | { |
---|
| 4482 | j++; |
---|
| 4483 | if(j>size(divList)-1) break; |
---|
| 4484 | continue; |
---|
| 4485 | } |
---|
| 4486 | if(defined(opath)){kill opath;} |
---|
| 4487 | def opath=imap(re[2][divList[j][1][1]],path); |
---|
| 4488 | oPa=int(leadcoef(opath[1,ncols(opath)])); |
---|
| 4489 | if(defined(SoPa)){kill SoPa;} |
---|
| 4490 | def SoPa=re[2][oPa]; |
---|
| 4491 | setring SoPa; |
---|
| 4492 | odim=dim(std(BO[1]+cent)); |
---|
| 4493 | setring Sm; |
---|
| 4494 | if(mdim!=odim) |
---|
| 4495 | { |
---|
| 4496 | //--- different dimension ==> cannot be same center |
---|
| 4497 | j++; |
---|
| 4498 | if(j>size(divList)-1) break; |
---|
| 4499 | continue; |
---|
| 4500 | } |
---|
| 4501 | comPa=1; |
---|
| 4502 | while(path[1,comPa]==opath[1,comPa]) |
---|
| 4503 | { |
---|
| 4504 | comPa++; |
---|
| 4505 | if((comPa>ncols(path))||(comPa>ncols(opath))) break; |
---|
| 4506 | } |
---|
| 4507 | comPa=int(leadcoef(path[1,comPa-1])); |
---|
| 4508 | if(defined(SPa)){kill SPa;} |
---|
| 4509 | def SPa=re[2][mPa]; |
---|
| 4510 | setring SPa; |
---|
| 4511 | if(defined(tempIdE)){kill tempIdE;} |
---|
| 4512 | ideal tempIdE=fetchInTree(re,oPa,comPa,mPa,"cent",divList); |
---|
| 4513 | if((size(reduce(cent,std(tempIdE)))!=0)|| |
---|
| 4514 | (size(reduce(tempIdE,std(cent)))!=0)) |
---|
| 4515 | { |
---|
| 4516 | //--- it is not the same divisor! |
---|
| 4517 | j++; |
---|
| 4518 | if(j>size(divList)) |
---|
| 4519 | { |
---|
| 4520 | break; |
---|
| 4521 | } |
---|
| 4522 | else |
---|
| 4523 | { |
---|
| 4524 | continue; |
---|
| 4525 | } |
---|
| 4526 | } |
---|
| 4527 | for(k=1;k<=size(divList[j]);k++) |
---|
| 4528 | { |
---|
| 4529 | //--- append the entries of the j-th divisor (which is actually also the i-th) |
---|
| 4530 | //--- to the i-th divisor |
---|
| 4531 | divList[i][size(divList[i])+1]=divList[j][k]; |
---|
| 4532 | } |
---|
| 4533 | divList=delete(divList,j); //kill obsolete entry from the list |
---|
| 4534 | for(k=1;k<=nrows(M);k++) |
---|
| 4535 | { |
---|
| 4536 | for(a=1;a<=ncols(M);a++) |
---|
| 4537 | { |
---|
| 4538 | if(M[k,a]==j) |
---|
| 4539 | { |
---|
| 4540 | //--- j-th divisor is actually the i-th one |
---|
| 4541 | M[k,a]=i; |
---|
| 4542 | } |
---|
| 4543 | if(M[k,a]>j) |
---|
| 4544 | { |
---|
| 4545 | //--- index j was deleted from the list ==> all subsequent indices dropped by |
---|
| 4546 | //--- one |
---|
| 4547 | M[k,a]=M[k,a]-1; |
---|
| 4548 | } |
---|
| 4549 | } |
---|
| 4550 | } |
---|
| 4551 | j--; //do not forget to consider new j-th entry |
---|
| 4552 | } |
---|
| 4553 | } |
---|
| 4554 | setring R; |
---|
| 4555 | list retlist=M,divList; |
---|
| 4556 | return(retlist); |
---|
| 4557 | } |
---|
| 4558 | ///////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 4559 | static proc findTrans(ideal Z, ideal E, list notE, list #) |
---|
[2e6eac2] | 4560 | "Internal procedure - no help and no example available |
---|
| 4561 | " |
---|
| 4562 | { |
---|
| 4563 | //---Auxilliary procedure for fetchInTree! |
---|
| 4564 | //---Assume E prime ideal, Z+E eqidimensional, |
---|
[3754ca] | 4565 | //---ht(E)+r=ht(Z+E). Compute P=<p[1],...,p[r]> in Z+E, and polynomial f, |
---|
[2e6eac2] | 4566 | //---such that radical(Z+E)=radical((E+P):f) |
---|
| 4567 | int i,j,d,e; |
---|
| 4568 | ideal Estd=std(E); |
---|
| 4569 | //!!! alternative to subsequent line: |
---|
| 4570 | //!!! ideal Zstd=std(radical(Z+E)); |
---|
| 4571 | ideal Zstd=std(Z+E); |
---|
| 4572 | ideal J=1; |
---|
| 4573 | if(size(#)>0) |
---|
| 4574 | { |
---|
| 4575 | J=#[1]; |
---|
| 4576 | } |
---|
| 4577 | if(deg(Zstd[1])==0){return(list(ideal(1),poly(1)));} |
---|
| 4578 | for(i=1;i<=size(notE);i++) |
---|
| 4579 | { |
---|
| 4580 | notE[i]=std(notE[i]); |
---|
| 4581 | } |
---|
| 4582 | ideal Zred=simplify(reduce(Z,Estd),2); |
---|
| 4583 | if(size(Zred)==0){Z,Estd;~;ERROR("Z is contained in E");} |
---|
| 4584 | ideal P,Q,Qstd; |
---|
| 4585 | Q=Estd; |
---|
| 4586 | attrib(Q,"isSB",1); |
---|
| 4587 | d=dim(Estd); |
---|
| 4588 | e=dim(Zstd); |
---|
| 4589 | for(i=1;i<=size(Zred);i++) |
---|
| 4590 | { |
---|
| 4591 | Qstd=std(Q,Zred[i]); |
---|
| 4592 | if(dim(Qstd)<d) |
---|
| 4593 | { |
---|
| 4594 | d=dim(Qstd); |
---|
| 4595 | P[size(P)+1]=Zred[i]; |
---|
| 4596 | Q=Qstd; |
---|
| 4597 | attrib(Q,"isSB",1); |
---|
| 4598 | if(d==e) break; |
---|
| 4599 | } |
---|
| 4600 | } |
---|
| 4601 | list pr=minAssGTZ(E+P); |
---|
| 4602 | list sr=minAssGTZ(J+P); |
---|
| 4603 | i=0; |
---|
| 4604 | Q=1; |
---|
| 4605 | list qr; |
---|
| 4606 | |
---|
| 4607 | while(i<size(pr)) |
---|
| 4608 | { |
---|
| 4609 | i++; |
---|
| 4610 | Qstd=std(pr[i]); |
---|
| 4611 | Zred=simplify(reduce(Zstd,Qstd),2); |
---|
| 4612 | if(size(Zred)==0) |
---|
| 4613 | { |
---|
| 4614 | qr[size(qr)+1]=pr[i]; |
---|
| 4615 | pr=delete(pr,i); |
---|
| 4616 | i--; |
---|
| 4617 | } |
---|
| 4618 | else |
---|
| 4619 | { |
---|
| 4620 | Q=intersect(Q,pr[i]); |
---|
| 4621 | } |
---|
| 4622 | } |
---|
| 4623 | i=0; |
---|
| 4624 | while(i<size(sr)) |
---|
| 4625 | { |
---|
| 4626 | i++; |
---|
| 4627 | Qstd=std(sr[i]+E); |
---|
| 4628 | Zred=simplify(reduce(Zstd,Qstd),2); |
---|
| 4629 | if((size(Zred)!=0)||(dim(Qstd)!=dim(Zstd))) |
---|
| 4630 | { |
---|
| 4631 | Q=intersect(Q,sr[i]); |
---|
| 4632 | } |
---|
| 4633 | } |
---|
| 4634 | poly f; |
---|
| 4635 | for(i=1;i<=size(Q);i++) |
---|
| 4636 | { |
---|
| 4637 | f=Q[i]; |
---|
| 4638 | for(e=1;e<=size(qr);e++) |
---|
| 4639 | { |
---|
| 4640 | if(reduce(f,std(qr[e]))==0){f=0;break;} |
---|
| 4641 | } |
---|
| 4642 | for(j=1;j<=size(notE);j++) |
---|
| 4643 | { |
---|
| 4644 | if(reduce(f,notE[j])==0){f=0; break;} |
---|
| 4645 | } |
---|
| 4646 | if(f!=0) break; |
---|
| 4647 | } |
---|
| 4648 | i=0; |
---|
| 4649 | while(f==0) |
---|
| 4650 | { |
---|
| 4651 | i++; |
---|
| 4652 | f=randomid(Q)[1]; |
---|
| 4653 | for(e=1;e<=size(qr);e++) |
---|
| 4654 | { |
---|
| 4655 | if(reduce(f,std(qr[e]))==0){f=0;break;} |
---|
| 4656 | } |
---|
| 4657 | for(j=1;j<=size(notE);j++) |
---|
| 4658 | { |
---|
| 4659 | if(reduce(f,notE[j])==0){f=0; break;} |
---|
| 4660 | } |
---|
| 4661 | if(f!=0) break; |
---|
| 4662 | if(i>20) |
---|
| 4663 | { |
---|
| 4664 | ~; |
---|
| 4665 | ERROR("findTrans:Hier ist was faul"); |
---|
| 4666 | } |
---|
| 4667 | } |
---|
| 4668 | |
---|
| 4669 | list resu=P,f; |
---|
| 4670 | return(resu); |
---|
| 4671 | } |
---|
| 4672 | ///////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 4673 | static proc compareE(list L, int m, int o, list DivL) |
---|
[2e6eac2] | 4674 | "Internal procedure - no help and no example available |
---|
| 4675 | " |
---|
| 4676 | { |
---|
| 4677 | //---------------------------------------------------------------------------- |
---|
| 4678 | // We want to compare the divisors BO[4][size(BO[4])] of the rings |
---|
| 4679 | // L[2][m] and L[2][o]. |
---|
| 4680 | // In the initialization step, we collect all necessary data from those |
---|
| 4681 | // those rings. In particular, we determine at what point (in the resolution |
---|
| 4682 | // history) the branches for L[2][m] and L[2][o] were separated, denoting |
---|
| 4683 | // the corresponding ring indices by mPa, oPa and comPa. |
---|
| 4684 | //---------------------------------------------------------------------------- |
---|
| 4685 | def R=basering; |
---|
| 4686 | int i,j,k,len; |
---|
| 4687 | |
---|
| 4688 | //-- find direct parents and branching point in resolution history |
---|
| 4689 | matrix tpm=imap(L[2][m],path); |
---|
| 4690 | matrix tpo=imap(L[2][o],path); |
---|
| 4691 | int m1,o1=int(leadcoef(tpm[1,ncols(tpm)])), |
---|
| 4692 | int(leadcoef(tpo[1,ncols(tpo)])); |
---|
| 4693 | while((i<ncols(tpo)) && (i<ncols(tpm))) |
---|
| 4694 | { |
---|
| 4695 | if(tpm[1,i+1]!=tpo[1,i+1]) break; |
---|
| 4696 | i++; |
---|
| 4697 | } |
---|
| 4698 | int branchpos=i; |
---|
| 4699 | int comPa=int(leadcoef(tpm[1,branchpos])); // last common ancestor |
---|
| 4700 | //---------------------------------------------------------------------------- |
---|
| 4701 | // simple checks to save us some work in obvious cases |
---|
| 4702 | //---------------------------------------------------------------------------- |
---|
| 4703 | if((comPa==m1)||(comPa==o1)) |
---|
| 4704 | { |
---|
| 4705 | //--- one is in the history of the other ==> they cannot give rise |
---|
| 4706 | //--- to the same divisor |
---|
| 4707 | return(0); |
---|
| 4708 | } |
---|
| 4709 | def T=L[2][o1]; |
---|
| 4710 | setring T; |
---|
| 4711 | int dimCo1=dim(std(cent+BO[1])); |
---|
| 4712 | def S=L[2][m1]; |
---|
| 4713 | setring S; |
---|
| 4714 | int dimCm1=dim(std(cent+BO[1])); |
---|
| 4715 | if(dimCm1!=dimCo1) |
---|
| 4716 | { |
---|
| 4717 | //--- centers do not have same dimension ==> they cannot give rise |
---|
| 4718 | //--- to the same divisor |
---|
| 4719 | return(0); |
---|
| 4720 | } |
---|
| 4721 | //---------------------------------------------------------------------------- |
---|
| 4722 | // fetch the center via the tree for comparison |
---|
| 4723 | //---------------------------------------------------------------------------- |
---|
| 4724 | if(defined(invLocus0)) {kill invLocus0;} |
---|
| 4725 | ideal invLocus0=fetchInTree(L,o1,comPa,m1,"cent",DivL); |
---|
| 4726 | // blow down from L[2][o1] to L[2][comPa] and then up to L[2][m1] |
---|
| 4727 | if(deg(std(invLocus0+invCenter[1]+BO[1])[1])!=0) |
---|
| 4728 | { |
---|
| 4729 | setring R; |
---|
| 4730 | return(int(1)); |
---|
| 4731 | } |
---|
| 4732 | if(size(BO)>9) |
---|
| 4733 | { |
---|
| 4734 | for(i=1;i<=size(BO[10]);i++) |
---|
| 4735 | { |
---|
| 4736 | if(deg(std(invLocus0+BO[10][i][1]+BO[1])[1])!=0) |
---|
| 4737 | { |
---|
| 4738 | if(dim(std(BO[10][i][1]+BO[1])) > |
---|
| 4739 | dim(std(invLocus0+BO[10][i][1]+BO[1]))) |
---|
| 4740 | { |
---|
| 4741 | ERROR("Internal Error: Please send this example to the authors."); |
---|
| 4742 | } |
---|
| 4743 | setring R; |
---|
| 4744 | return(int(2)); |
---|
| 4745 | } |
---|
| 4746 | } |
---|
| 4747 | } |
---|
| 4748 | setring R; |
---|
| 4749 | return(int(0)); |
---|
| 4750 | //---------------------------------------------------------------------------- |
---|
| 4751 | // Return-Values: |
---|
| 4752 | // TRUE (=1) if the exceptional divisors coincide, |
---|
| 4753 | // TRUE (=2) if the exceptional divisors originate from different |
---|
| 4754 | // components of the same center |
---|
| 4755 | // FALSE (=0) otherwise |
---|
| 4756 | //---------------------------------------------------------------------------- |
---|
| 4757 | } |
---|
| 4758 | ////////////////////////////////////////////////////////////////////////////// |
---|
| 4759 | |
---|
| 4760 | proc fetchInTree(list L, |
---|
| 4761 | int o1, |
---|
| 4762 | int comPa, |
---|
| 4763 | int m1, |
---|
| 4764 | string idname, |
---|
| 4765 | list DivL, |
---|
| 4766 | list #); |
---|
| 4767 | "Internal procedure - no help and no example available |
---|
| 4768 | " |
---|
| 4769 | { |
---|
| 4770 | //---------------------------------------------------------------------------- |
---|
| 4771 | // Initialization and Sanity Checks |
---|
| 4772 | //---------------------------------------------------------------------------- |
---|
| 4773 | int i,j,k,m,branchPos,inJ,exception; |
---|
| 4774 | string algext; |
---|
| 4775 | //--- we need to be in L[2][m1] |
---|
| 4776 | def R=basering; |
---|
| 4777 | ideal test_for_the_same_ring=-77; |
---|
| 4778 | def Sm1=L[2][m1]; |
---|
| 4779 | setring Sm1; |
---|
| 4780 | if(!defined(test_for_the_same_ring)) |
---|
| 4781 | { |
---|
| 4782 | //--- we are not in L[2][m1] |
---|
| 4783 | ERROR("basering has to coincide with L[2][m1]"); |
---|
| 4784 | } |
---|
| 4785 | else |
---|
| 4786 | { |
---|
| 4787 | //--- we are in L[2][m1] |
---|
| 4788 | kill test_for_the_same_ring; |
---|
| 4789 | } |
---|
| 4790 | //--- non-embedded case? |
---|
| 4791 | if(size(#)>0) |
---|
| 4792 | { |
---|
| 4793 | inJ=1; |
---|
| 4794 | } |
---|
| 4795 | //--- do parameter values make sense? |
---|
| 4796 | if(comPa<1) |
---|
| 4797 | { |
---|
| 4798 | ERROR("Common Parent should at least be the first ring!"); |
---|
| 4799 | } |
---|
| 4800 | //--- do we need to pass to an algebraic field extension of Q? |
---|
| 4801 | if(typeof(attrib(idname,"algext"))=="string") |
---|
| 4802 | { |
---|
| 4803 | algext=attrib(idname,"algext"); |
---|
| 4804 | } |
---|
| 4805 | //--- check wheter comPa is in the history of m1 |
---|
| 4806 | //--- same test for o1 can be done later on (on the fly) |
---|
| 4807 | if(m1==comPa) |
---|
| 4808 | { |
---|
| 4809 | j=1; |
---|
| 4810 | i=ncols(path)+1; |
---|
| 4811 | } |
---|
| 4812 | else |
---|
| 4813 | { |
---|
| 4814 | for(i=1;i<=ncols(path);i++) |
---|
| 4815 | { |
---|
| 4816 | if(int(leadcoef(path[1,i]))==comPa) |
---|
| 4817 | { |
---|
| 4818 | //--- comPa occurs in the history |
---|
| 4819 | j=1; |
---|
| 4820 | break; |
---|
| 4821 | } |
---|
| 4822 | } |
---|
| 4823 | } |
---|
| 4824 | branchPos=i; |
---|
| 4825 | if(j==0) |
---|
| 4826 | { |
---|
| 4827 | ERROR("L[2][comPa] not in history of L[2][m1]!"); |
---|
| 4828 | } |
---|
| 4829 | //---------------------------------------------------------------------------- |
---|
| 4830 | // Blow down ideal "idname" from L[2][o1] to L[2][comPa], where the latter |
---|
| 4831 | // is assumed to be the common parent of L[2][o1] and L[2][m1] |
---|
| 4832 | //---------------------------------------------------------------------------- |
---|
| 4833 | if(size(algext)>0) |
---|
| 4834 | { |
---|
[2cd0ca] | 4835 | //--- size(algext)>0: case of algebraic extension of base field |
---|
[2e6eac2] | 4836 | if(defined(tstr)){kill tstr;} |
---|
| 4837 | string tstr="ring So1=(0,t),("+varstr(L[2][o1])+"),("+ordstr(L[2][o1])+");"; |
---|
| 4838 | execute(tstr); |
---|
| 4839 | setring So1; |
---|
| 4840 | execute(algext); |
---|
| 4841 | minpoly=leadcoef(p); |
---|
| 4842 | if(defined(id1)) { kill id1; } |
---|
| 4843 | if(defined(id2)) { kill id2; } |
---|
| 4844 | if(defined(idlist)) { kill idlist; } |
---|
| 4845 | execute("int bool2=defined("+idname+");"); |
---|
| 4846 | if(bool2==0) |
---|
| 4847 | { |
---|
| 4848 | execute("list ttlist=imap(L[2][o1],"+idname+");"); |
---|
| 4849 | } |
---|
| 4850 | else |
---|
| 4851 | { |
---|
| 4852 | execute("list ttlist="+idname+";"); |
---|
| 4853 | } |
---|
| 4854 | kill bool2; |
---|
| 4855 | def BO=imap(L[2][o1],BO); |
---|
| 4856 | def path=imap(L[2][o1],path); |
---|
| 4857 | def lastMap=imap(L[2][o1],lastMap); |
---|
| 4858 | ideal id2=1; |
---|
| 4859 | if(defined(notE)){kill notE;} |
---|
| 4860 | list notE; |
---|
| 4861 | intvec nE; |
---|
| 4862 | list idlist; |
---|
| 4863 | for(i=1;i<=size(ttlist);i++) |
---|
| 4864 | { |
---|
| 4865 | if((i==size(ttlist))&&(typeof(ttlist[i])!="string")) break; |
---|
| 4866 | execute("ideal tid="+ttlist[i]+";"); |
---|
| 4867 | idlist[i]=list(tid,ideal(1),nE); |
---|
| 4868 | kill tid; |
---|
| 4869 | } |
---|
| 4870 | } |
---|
| 4871 | else |
---|
| 4872 | { |
---|
[2cd0ca] | 4873 | //--- size(algext)==0: no algebraic extension of base needed |
---|
[2e6eac2] | 4874 | def So1=L[2][o1]; |
---|
| 4875 | setring So1; |
---|
| 4876 | if(defined(id1)) { kill id1; } |
---|
| 4877 | if(defined(id2)) { kill id2; } |
---|
| 4878 | if(defined(idlist)) { kill idlist; } |
---|
| 4879 | execute("ideal id1="+idname+";"); |
---|
| 4880 | if(deg(std(id1)[1])==0) |
---|
| 4881 | { |
---|
| 4882 | //--- problems with findTrans if id1 is empty set |
---|
| 4883 | //!!! todo: also correct in if branch!!! |
---|
| 4884 | setring R; |
---|
| 4885 | return(ideal(1)); |
---|
| 4886 | } |
---|
| 4887 | // id1=radical(id1); |
---|
| 4888 | ideal id2=1; |
---|
| 4889 | list idlist; |
---|
| 4890 | if(defined(notE)){kill notE;} |
---|
| 4891 | list notE; |
---|
| 4892 | intvec nE; |
---|
| 4893 | idlist[1]=list(id1,id2,nE); |
---|
[101775] | 4894 | } |
---|
[2e6eac2] | 4895 | if(defined(tli)){kill tli;} |
---|
| 4896 | list tli; |
---|
| 4897 | if(defined(id1)) { kill id1; } |
---|
| 4898 | if(defined(id2)) { kill id2; } |
---|
| 4899 | ideal id1; |
---|
| 4900 | ideal id2; |
---|
| 4901 | if(defined(Etemp)){kill Etemp;} |
---|
| 4902 | ideal Etemp; |
---|
| 4903 | for(m=1;m<=size(idlist);m++) |
---|
| 4904 | { |
---|
[2cd0ca] | 4905 | //!!! Duplicate Block!!! All changes also needed below!!! |
---|
| 4906 | //!!! no subprocedure due to large data overhead!!! |
---|
| 4907 | //--- run through all ideals to be fetched |
---|
[2e6eac2] | 4908 | id1=idlist[m][1]; |
---|
| 4909 | id2=idlist[m][2]; |
---|
| 4910 | nE=idlist[m][3]; |
---|
| 4911 | for(i=branchPos-1;i<=size(BO[4]);i++) |
---|
| 4912 | { |
---|
[2cd0ca] | 4913 | //--- run through all relevant exceptional divisors |
---|
[2e6eac2] | 4914 | if(size(reduce(BO[4][i],std(id1+BO[1])))==0) |
---|
| 4915 | { |
---|
[2cd0ca] | 4916 | //--- V(id1) is contained in except. div. i in this chart |
---|
[2e6eac2] | 4917 | if(size(reduce(id1,std(BO[4][i])))!=0) |
---|
| 4918 | { |
---|
[2cd0ca] | 4919 | //--- V(id1) does not equal except. div. i of this chart |
---|
[2e6eac2] | 4920 | Etemp=BO[4][i]; |
---|
| 4921 | if(npars(basering)>0) |
---|
| 4922 | { |
---|
[2cd0ca] | 4923 | //--- we are in an algebraic extension of the base field |
---|
[2e6eac2] | 4924 | if(defined(prtemp)){kill prtemp;} |
---|
[2cd0ca] | 4925 | list prtemp=minAssGTZ(BO[4][i]); // C-comp. of except. div. |
---|
[101775] | 4926 | j=1; |
---|
[2e6eac2] | 4927 | if(size(prtemp)>1) |
---|
| 4928 | { |
---|
[2cd0ca] | 4929 | //--- more than 1 component |
---|
[2e6eac2] | 4930 | Etemp=ideal(1); |
---|
| 4931 | for(j=1;j<=size(prtemp);j++) |
---|
| 4932 | { |
---|
[2cd0ca] | 4933 | //--- find correct component |
---|
[2e6eac2] | 4934 | if(size(reduce(prtemp[j],std(id1)))==0) |
---|
| 4935 | { |
---|
| 4936 | Etemp=prtemp[j]; |
---|
| 4937 | break; |
---|
| 4938 | } |
---|
| 4939 | } |
---|
| 4940 | if(deg(std(Etemp)[1])==0) |
---|
| 4941 | { |
---|
| 4942 | ERROR("fetchInTree:something wrong in field extension"); |
---|
| 4943 | } |
---|
| 4944 | } |
---|
[2cd0ca] | 4945 | prtemp=delete(prtemp,j); // remove this comp. from list |
---|
| 4946 | while(size(prtemp)>1) |
---|
| 4947 | { |
---|
| 4948 | //--- collect all the others into prtemp[1] |
---|
| 4949 | prtemp[1]=intersect(prtemp[1],prtemp[size(prtemp)]); |
---|
| 4950 | prtemp=delete(prtemp,size(prtemp)); |
---|
| 4951 | } |
---|
[2e6eac2] | 4952 | } |
---|
[101775] | 4953 | //--- determine tli[1] and tli[2] such that |
---|
[2cd0ca] | 4954 | //--- V(id1) \cap D(id2) = V(tli[1]) \cap D(tli[2]) \cap BO[4][i] |
---|
| 4955 | //--- inside V(BO[1]) (and if necessary inside V(BO[1]+BO[2])) |
---|
[2e6eac2] | 4956 | if(inJ) |
---|
| 4957 | { |
---|
[2cd0ca] | 4958 | tli=findTrans(id1+BO[2]+BO[1],Etemp,notE,BO[2]); |
---|
[2e6eac2] | 4959 | } |
---|
| 4960 | else |
---|
| 4961 | { |
---|
[2cd0ca] | 4962 | tli=findTrans(id1+BO[1],Etemp,notE); |
---|
| 4963 | } |
---|
| 4964 | if(npars(basering)>0) |
---|
| 4965 | { |
---|
| 4966 | //--- in algebraic extension: make sure we stay outside the other components |
---|
| 4967 | if(size(prtemp)>0) |
---|
| 4968 | { |
---|
| 4969 | for(j=1;j<=ncols(prtemp[1]);j++) |
---|
| 4970 | { |
---|
| 4971 | //--- find the (univariate) generator of prtemp[1] which is the remaining |
---|
| 4972 | //--- factor from the factorization over the extension field |
---|
| 4973 | if(size(reduce(prtemp[1][j],std(id1)))>0) |
---|
| 4974 | { |
---|
| 4975 | tli[2]=tli[2]*prtemp[1][j]; |
---|
| 4976 | } |
---|
| 4977 | } |
---|
| 4978 | } |
---|
[2e6eac2] | 4979 | } |
---|
| 4980 | } |
---|
| 4981 | else |
---|
| 4982 | { |
---|
[2cd0ca] | 4983 | //--- V(id1) equals except. div. i of this chart |
---|
[2e6eac2] | 4984 | tli[1]=ideal(0); |
---|
| 4985 | tli[2]=ideal(1); |
---|
| 4986 | } |
---|
| 4987 | id1=tli[1]; |
---|
| 4988 | id2=id2*tli[2]; |
---|
| 4989 | notE[size(notE)+1]=BO[4][i]; |
---|
| 4990 | for(j=1;j<=size(DivL);j++) |
---|
| 4991 | { |
---|
| 4992 | if(inIVList(intvec(o1,i),DivL[j])) |
---|
| 4993 | { |
---|
| 4994 | nE[size(nE)+1]=j; |
---|
| 4995 | break; |
---|
| 4996 | } |
---|
| 4997 | } |
---|
| 4998 | if(size(nE)<size(notE)) |
---|
| 4999 | { |
---|
| 5000 | ERROR("fetchInTree: divisor not found in divL"); |
---|
| 5001 | } |
---|
| 5002 | } |
---|
| 5003 | idlist[m][1]=id1; |
---|
| 5004 | idlist[m][2]=id2; |
---|
| 5005 | idlist[m][3]=nE; |
---|
| 5006 | } |
---|
[2cd0ca] | 5007 | //!!! End of Duplicate Block !!!! |
---|
[2e6eac2] | 5008 | } |
---|
| 5009 | if(o1>1) |
---|
| 5010 | { |
---|
| 5011 | while(int(leadcoef(path[1,ncols(path)]))>=comPa) |
---|
| 5012 | { |
---|
| 5013 | if((int(leadcoef(path[1,ncols(path)]))>comPa)&& |
---|
| 5014 | (int(leadcoef(path[1,ncols(path)-1]))<comPa)) |
---|
| 5015 | { |
---|
| 5016 | ERROR("L[2][comPa] not in history of L[2][o1]!"); |
---|
| 5017 | } |
---|
| 5018 | def S=basering; |
---|
| 5019 | if(int(leadcoef(path[1,ncols(path)]))==1) |
---|
| 5020 | { |
---|
| 5021 | //--- that's the very first ring!!! |
---|
| 5022 | int und_jetzt_raus; |
---|
| 5023 | } |
---|
| 5024 | if(defined(T)){kill T;} |
---|
| 5025 | if(size(algext)>0) |
---|
| 5026 | { |
---|
| 5027 | if(defined(T0)){kill T0;} |
---|
| 5028 | def T0=L[2][int(leadcoef(path[1,ncols(path)]))]; |
---|
| 5029 | if(defined(tstr)){kill tstr;} |
---|
| 5030 | string tstr="ring T=(0,t),(" |
---|
| 5031 | +varstr(L[2][int(leadcoef(path[1,ncols(path)]))])+"),(" |
---|
| 5032 | +ordstr(L[2][int(leadcoef(path[1,ncols(path)]))])+");"; |
---|
| 5033 | execute(tstr); |
---|
| 5034 | setring T; |
---|
| 5035 | execute(algext); |
---|
| 5036 | minpoly=leadcoef(p); |
---|
| 5037 | kill tstr; |
---|
| 5038 | def BO=imap(T0,BO); |
---|
| 5039 | if(!defined(und_jetzt_raus)) |
---|
| 5040 | { |
---|
| 5041 | def path=imap(T0,path); |
---|
| 5042 | def lastMap=imap(T0,lastMap); |
---|
| 5043 | } |
---|
| 5044 | if(defined(idlist)){kill idlist;} |
---|
| 5045 | list idlist=list(list(ideal(1),ideal(1))); |
---|
| 5046 | } |
---|
| 5047 | else |
---|
| 5048 | { |
---|
| 5049 | def T=L[2][int(leadcoef(path[1,ncols(path)]))]; |
---|
| 5050 | setring T; |
---|
| 5051 | if(defined(id1)) { kill id1; } |
---|
| 5052 | if(defined(id2)) { kill id2; } |
---|
| 5053 | if(defined(idlist)){kill idlist;} |
---|
| 5054 | list idlist=list(list(ideal(1),ideal(1))); |
---|
| 5055 | } |
---|
| 5056 | setring S; |
---|
| 5057 | if(defined(phi)) { kill phi; } |
---|
| 5058 | map phi=T,lastMap; |
---|
[2cd0ca] | 5059 | //--- now do the actual blowing down ... |
---|
[2e6eac2] | 5060 | for(m=1;m<=size(idlist);m++) |
---|
| 5061 | { |
---|
[2cd0ca] | 5062 | //--- ... for each entry of idlist separately |
---|
[2e6eac2] | 5063 | if(defined(id1)){kill id1;} |
---|
| 5064 | if(defined(id2)){kill id2;} |
---|
| 5065 | ideal id1=idlist[m][1]+BO[1]; |
---|
[2cd0ca] | 5066 | ideal id2=idlist[m][2]; |
---|
[2e6eac2] | 5067 | nE=idlist[m][3]; |
---|
[2cd0ca] | 5068 | if(defined(debug_fetchInTree)>0) |
---|
| 5069 | { |
---|
| 5070 | "Blowing down entry",m,"of idlist:"; |
---|
| 5071 | setring S; |
---|
| 5072 | "Abbildung:";phi; |
---|
| 5073 | "before preimage"; |
---|
| 5074 | id1; |
---|
| 5075 | id2; |
---|
| 5076 | } |
---|
[2e6eac2] | 5077 | setring T; |
---|
| 5078 | ideal id1=preimage(S,phi,id1); |
---|
| 5079 | ideal id2=preimage(S,phi,id2); |
---|
[2cd0ca] | 5080 | if(defined(debug_fetchInTree)>0) |
---|
| 5081 | { |
---|
| 5082 | "after preimage"; |
---|
| 5083 | id1; |
---|
| 5084 | id2; |
---|
| 5085 | } |
---|
| 5086 | if(size(id2)==0) |
---|
| 5087 | { |
---|
[101775] | 5088 | //--- preimage of (principal ideal) id2 was zero, i.e. |
---|
[2cd0ca] | 5089 | //--- generator of previous id2 not in image |
---|
| 5090 | setring S; |
---|
| 5091 | //--- it might just be one offending factor ==> factorize |
---|
| 5092 | ideal id2factors=factorize(id2[1])[1]; |
---|
| 5093 | int zzz=size(id2factors); |
---|
| 5094 | ideal curfactor; |
---|
| 5095 | setring T; |
---|
| 5096 | id2=ideal(1); |
---|
| 5097 | ideal curfactor; |
---|
| 5098 | for(int mm=1;mm<=zzz;mm++) |
---|
| 5099 | { |
---|
| 5100 | //--- blow down each factor separately |
---|
| 5101 | setring S; |
---|
| 5102 | curfactor=id2factors[mm]; |
---|
| 5103 | setring T; |
---|
| 5104 | curfactor=preimage(S,phi,curfactor); |
---|
| 5105 | if(size(curfactor)>0) |
---|
| 5106 | { |
---|
| 5107 | id2[1]=id2[1]*curfactor[1]; |
---|
| 5108 | } |
---|
| 5109 | } |
---|
| 5110 | kill curfactor; |
---|
| 5111 | setring S; |
---|
| 5112 | kill curfactor; |
---|
| 5113 | kill id2factors; |
---|
| 5114 | setring T; |
---|
| 5115 | kill mm; |
---|
| 5116 | kill zzz; |
---|
| 5117 | if(defined(debug_fetchInTree)>0) |
---|
| 5118 | { |
---|
| 5119 | "corrected id2:"; |
---|
| 5120 | id2; |
---|
| 5121 | } |
---|
| 5122 | } |
---|
[2e6eac2] | 5123 | idlist[m]=list(id1,id2,nE); |
---|
| 5124 | kill id1,id2; |
---|
| 5125 | setring S; |
---|
| 5126 | } |
---|
| 5127 | setring T; |
---|
| 5128 | //--- after blowing down we might again be sitting inside a relevant |
---|
| 5129 | //--- exceptional divisor |
---|
| 5130 | for(m=1;m<=size(idlist);m++) |
---|
| 5131 | { |
---|
[2cd0ca] | 5132 | //!!! Duplicate Block!!! All changes also needed above!!! |
---|
| 5133 | //!!! no subprocedure due to large data overhead!!! |
---|
| 5134 | //--- run through all ideals to be fetched |
---|
[2e6eac2] | 5135 | if(defined(id1)) {kill id1;} |
---|
| 5136 | if(defined(id2)) {kill id2;} |
---|
| 5137 | if(defined(notE)) {kill notE;} |
---|
| 5138 | if(defined(notE)) {kill notE;} |
---|
| 5139 | list notE; |
---|
| 5140 | ideal id1=idlist[m][1]; |
---|
| 5141 | ideal id2=idlist[m][2]; |
---|
| 5142 | nE=idlist[m][3]; |
---|
| 5143 | for(i=branchPos-1;i<=size(BO[4]);i++) |
---|
| 5144 | { |
---|
[2cd0ca] | 5145 | //--- run through all relevant exceptional divisors |
---|
[2e6eac2] | 5146 | if(size(reduce(BO[4][i],std(id1)))==0) |
---|
| 5147 | { |
---|
[2cd0ca] | 5148 | //--- V(id1) is contained in except. div. i in this chart |
---|
[2e6eac2] | 5149 | if(size(reduce(id1,std(BO[4][i])))!=0) |
---|
| 5150 | { |
---|
[2cd0ca] | 5151 | //--- V(id1) does not equal except. div. i of this chart |
---|
[2e6eac2] | 5152 | if(defined(Etemp)) {kill Etemp;} |
---|
| 5153 | ideal Etemp=BO[4][i]; |
---|
| 5154 | if(npars(basering)>0) |
---|
| 5155 | { |
---|
[2cd0ca] | 5156 | //--- we are in an algebraic extension of the base field |
---|
[2e6eac2] | 5157 | if(defined(prtemp)){kill prtemp;} |
---|
[2cd0ca] | 5158 | list prtemp=minAssGTZ(BO[4][i]); // C-comp.except.div. |
---|
[2e6eac2] | 5159 | if(size(prtemp)>1) |
---|
| 5160 | { |
---|
[2cd0ca] | 5161 | //--- more than 1 component |
---|
[2e6eac2] | 5162 | Etemp=ideal(1); |
---|
| 5163 | for(j=1;j<=size(prtemp);j++) |
---|
| 5164 | { |
---|
[2cd0ca] | 5165 | //--- find correct component |
---|
[2e6eac2] | 5166 | if(size(reduce(prtemp[j],std(id1)))==0) |
---|
| 5167 | { |
---|
| 5168 | Etemp=prtemp[j]; |
---|
| 5169 | break; |
---|
| 5170 | } |
---|
| 5171 | } |
---|
| 5172 | if(deg(std(Etemp)[1])==0) |
---|
| 5173 | { |
---|
| 5174 | ERROR("fetchInTree:something wrong in field extension"); |
---|
| 5175 | } |
---|
| 5176 | } |
---|
[2cd0ca] | 5177 | prtemp=delete(prtemp,j); // remove this comp. from list |
---|
| 5178 | while(size(prtemp)>1) |
---|
| 5179 | { |
---|
| 5180 | //--- collect all the others into prtemp[1] |
---|
| 5181 | prtemp[1]=intersect(prtemp[1],prtemp[size(prtemp)]); |
---|
| 5182 | prtemp=delete(prtemp,size(prtemp)); |
---|
| 5183 | } |
---|
[2e6eac2] | 5184 | } |
---|
| 5185 | if(defined(tli)) {kill tli;} |
---|
[101775] | 5186 | //--- determine tli[1] and tli[2] such that |
---|
[2cd0ca] | 5187 | //--- V(id1) \cap D(id2) = V(tli[1]) \cap D(tli[2]) \cap BO[4][i] |
---|
| 5188 | //--- inside V(BO[1]) (and if necessary inside V(BO[1]+BO[2])) |
---|
[2e6eac2] | 5189 | if(inJ) |
---|
| 5190 | { |
---|
[2cd0ca] | 5191 | def tli=findTrans(id1+BO[2]+BO[1],Etemp,notE,BO[2]); |
---|
[2e6eac2] | 5192 | } |
---|
| 5193 | else |
---|
| 5194 | { |
---|
[2cd0ca] | 5195 | def tli=findTrans(id1+BO[1],Etemp,notE); |
---|
[2e6eac2] | 5196 | } |
---|
[2cd0ca] | 5197 | if(npars(basering)>0) |
---|
| 5198 | { |
---|
| 5199 | //--- in algebraic extension: make sure we stay outside the other components |
---|
| 5200 | if(size(prtemp)>0) |
---|
| 5201 | { |
---|
| 5202 | for(j=1;j<=ncols(prtemp[1]);j++) |
---|
| 5203 | { |
---|
| 5204 | //--- find the (univariate) generator of prtemp[1] which is the remaining |
---|
| 5205 | //--- factor from the factorization over the extension field |
---|
| 5206 | if(size(reduce(prtemp[1][j],std(id1)))>0) |
---|
| 5207 | { |
---|
| 5208 | tli[2]=tli[2]*prtemp[1][j]; |
---|
| 5209 | } |
---|
| 5210 | } |
---|
| 5211 | } |
---|
| 5212 | } |
---|
[2e6eac2] | 5213 | } |
---|
| 5214 | else |
---|
| 5215 | { |
---|
| 5216 | tli[1]=ideal(0); |
---|
| 5217 | tli[2]=ideal(1); |
---|
| 5218 | } |
---|
| 5219 | id1=tli[1]; |
---|
| 5220 | id2=id2*tli[2]; |
---|
| 5221 | notE[size(notE)+1]=BO[4][i]; |
---|
| 5222 | for(j=1;j<=size(DivL);j++) |
---|
| 5223 | { |
---|
| 5224 | if(inIVList(intvec(o1,i),DivL[j])) |
---|
| 5225 | { |
---|
| 5226 | nE[size(nE)+1]=j; |
---|
| 5227 | break; |
---|
| 5228 | } |
---|
| 5229 | } |
---|
| 5230 | if(size(nE)<size(notE)) |
---|
| 5231 | { |
---|
| 5232 | ERROR("fetchInTree: divisor not found in divL"); |
---|
| 5233 | } |
---|
| 5234 | } |
---|
| 5235 | idlist[m][1]=id1; |
---|
| 5236 | idlist[m][2]=id2; |
---|
| 5237 | idlist[m][3]=nE; |
---|
| 5238 | } |
---|
[2cd0ca] | 5239 | //!!! End of Duplicate Block !!!! |
---|
[2e6eac2] | 5240 | } |
---|
| 5241 | kill S; |
---|
| 5242 | if(defined(und_jetzt_raus)) |
---|
| 5243 | { |
---|
| 5244 | kill und_jetzt_raus; |
---|
| 5245 | break; |
---|
| 5246 | } |
---|
| 5247 | } |
---|
[2cd0ca] | 5248 | if(defined(debug_fetchInTree)>0) |
---|
| 5249 | { |
---|
| 5250 | "idlist after current blow down step:"; |
---|
| 5251 | idlist; |
---|
| 5252 | } |
---|
| 5253 | } |
---|
| 5254 | if(defined(debug_fetchInTree)>0) |
---|
| 5255 | { |
---|
| 5256 | "Blowing down ended"; |
---|
[2e6eac2] | 5257 | } |
---|
| 5258 | //---------------------------------------------------------------------------- |
---|
| 5259 | // Blow up ideal id1 from L[2][comPa] to L[2][m1]. To this end, first |
---|
| 5260 | // determine the path to follow and save it in path_togo. |
---|
| 5261 | //---------------------------------------------------------------------------- |
---|
| 5262 | if(m1==comPa) |
---|
| 5263 | { |
---|
[2cd0ca] | 5264 | //--- no further blow ups needed |
---|
[2e6eac2] | 5265 | if(size(algext)==0) |
---|
| 5266 | { |
---|
[2cd0ca] | 5267 | //--- no field extension ==> we are done |
---|
[2e6eac2] | 5268 | return(idlist[1][1]); |
---|
| 5269 | } |
---|
| 5270 | else |
---|
| 5271 | { |
---|
[2cd0ca] | 5272 | //--- field extension ==> we need to encode the result |
---|
[2e6eac2] | 5273 | list retlist; |
---|
| 5274 | for(m=1;m<=size(idlist);m++) |
---|
| 5275 | { |
---|
| 5276 | retlist[m]=string(idlist[m][1]); |
---|
| 5277 | } |
---|
| 5278 | return(retlist); |
---|
| 5279 | } |
---|
| 5280 | } |
---|
[2cd0ca] | 5281 | //--- we need to blow up |
---|
[2e6eac2] | 5282 | if(defined(path_m1)) { kill path_m1; } |
---|
| 5283 | matrix path_m1=imap(Sm1,path); |
---|
| 5284 | intvec path_togo; |
---|
| 5285 | for(i=1;i<=ncols(path_m1);i++) |
---|
| 5286 | { |
---|
| 5287 | if(path_m1[1,i]>=comPa) |
---|
| 5288 | { |
---|
| 5289 | path_togo=path_togo,int(leadcoef(path_m1[1,i])); |
---|
| 5290 | } |
---|
| 5291 | } |
---|
| 5292 | path_togo=path_togo[2..size(path_togo)],m1; |
---|
| 5293 | i=1; |
---|
| 5294 | while(i<size(path_togo)) |
---|
| 5295 | { |
---|
[101775] | 5296 | //--- we need to blow up following the path path_togo through the tree |
---|
[2e6eac2] | 5297 | def S=basering; |
---|
| 5298 | if(defined(T)){kill T;} |
---|
| 5299 | if(size(algext)>0) |
---|
| 5300 | { |
---|
[2cd0ca] | 5301 | //--- in an algebraic extension of the base field |
---|
[2e6eac2] | 5302 | if(defined(T0)){kill T0;} |
---|
| 5303 | def T0=L[2][path_togo[i+1]]; |
---|
| 5304 | if(defined(tstr)){kill tstr;} |
---|
| 5305 | string tstr="ring T=(0,t),(" +varstr(T0)+"),(" +ordstr(T0)+");"; |
---|
| 5306 | execute(tstr); |
---|
| 5307 | setring T; |
---|
| 5308 | execute(algext); |
---|
| 5309 | minpoly=leadcoef(p); |
---|
| 5310 | kill tstr; |
---|
| 5311 | def path=imap(T0,path); |
---|
| 5312 | def BO=imap(T0,BO); |
---|
| 5313 | def lastMap=imap(T0,lastMap); |
---|
| 5314 | if(defined(phi)){kill phi;} |
---|
| 5315 | map phi=S,lastMap; |
---|
| 5316 | list idlist=phi(idlist); |
---|
[2cd0ca] | 5317 | if(defined(debug_fetchInTree)>0) |
---|
| 5318 | { |
---|
| 5319 | "in blowing up (algebraic extension case):"; |
---|
| 5320 | phi; |
---|
| 5321 | idlist; |
---|
| 5322 | } |
---|
[2e6eac2] | 5323 | } |
---|
| 5324 | else |
---|
| 5325 | { |
---|
| 5326 | def T=L[2][path_togo[i+1]]; |
---|
| 5327 | setring T; |
---|
| 5328 | if(defined(phi)) { kill phi; } |
---|
| 5329 | map phi=S,lastMap; |
---|
| 5330 | if(defined(idlist)) {kill idlist;} |
---|
| 5331 | list idlist=phi(idlist); |
---|
| 5332 | idlist[1][1]=radical(idlist[1][1]); |
---|
| 5333 | idlist[1][2]=radical(idlist[1][2]); |
---|
[2cd0ca] | 5334 | if(defined(debug_fetchInTree)>0) |
---|
| 5335 | { |
---|
| 5336 | "in blowing up (case without field extension):"; |
---|
| 5337 | phi; |
---|
| 5338 | idlist; |
---|
| 5339 | } |
---|
[2e6eac2] | 5340 | } |
---|
| 5341 | for(m=1;m<=size(idlist);m++) |
---|
| 5342 | { |
---|
[2cd0ca] | 5343 | //--- get rid of new exceptional divisor |
---|
[2e6eac2] | 5344 | idlist[m][1]=sat(idlist[m][1]+BO[1],BO[4][size(BO[4])])[1]; |
---|
| 5345 | idlist[m][2]=sat(idlist[m][2],BO[4][size(BO[4])])[1]; |
---|
| 5346 | } |
---|
[2cd0ca] | 5347 | if(defined(debug_fetchInTree)>0) |
---|
| 5348 | { |
---|
| 5349 | "after saturation:"; |
---|
| 5350 | idlist; |
---|
| 5351 | } |
---|
[2e6eac2] | 5352 | if((size(algext)==0)&&(deg(std(idlist[1][1])[1])==0)) |
---|
| 5353 | { |
---|
| 5354 | //--- strict transform empty in this chart, it will stay empty till the end |
---|
| 5355 | setring Sm1; |
---|
| 5356 | return(ideal(1)); |
---|
| 5357 | } |
---|
| 5358 | kill S; |
---|
| 5359 | i++; |
---|
| 5360 | } |
---|
[2cd0ca] | 5361 | if(defined(debug_fetchInTree)>0) |
---|
| 5362 | { |
---|
| 5363 | "End of blowing up steps"; |
---|
| 5364 | } |
---|
| 5365 | //--------------------------------------------------------------------------- |
---|
| 5366 | // prepare results for returning them |
---|
| 5367 | //--------------------------------------------------------------------------- |
---|
[2e6eac2] | 5368 | ideal E,bla; |
---|
| 5369 | intvec kv; |
---|
| 5370 | list retlist; |
---|
| 5371 | for(m=1;m<=size(idlist);m++) |
---|
| 5372 | { |
---|
| 5373 | for(j=2;j<=size(idlist[m][3]);j++) |
---|
| 5374 | { |
---|
| 5375 | kv=findInIVList(1,path_togo[size(path_togo)],DivL[idlist[m][3][j]]); |
---|
| 5376 | if(kv!=intvec(0)) |
---|
| 5377 | { |
---|
| 5378 | E=E+BO[4][kv[2]]; |
---|
| 5379 | } |
---|
| 5380 | } |
---|
| 5381 | bla=quotient(idlist[m][1]+E,idlist[m][2]); |
---|
| 5382 | retlist[m]=string(bla); |
---|
| 5383 | } |
---|
| 5384 | if(size(algext)==0) |
---|
| 5385 | { |
---|
| 5386 | return(bla); |
---|
| 5387 | } |
---|
| 5388 | return(retlist); |
---|
| 5389 | } |
---|
| 5390 | ///////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 5391 | static proc findInIVList(int pos, int val, list ivl) |
---|
[2e6eac2] | 5392 | "Internal procedure - no help and no example available |
---|
| 5393 | " |
---|
| 5394 | { |
---|
| 5395 | //--- find entry with value val at position pos in list of intvecs |
---|
| 5396 | //--- and return the corresponding entry |
---|
| 5397 | int i; |
---|
| 5398 | for(i=1;i<=size(ivl);i++) |
---|
| 5399 | { |
---|
| 5400 | if(ivl[i][pos]==val) |
---|
| 5401 | { |
---|
| 5402 | return(ivl[i]); |
---|
| 5403 | } |
---|
| 5404 | } |
---|
| 5405 | return(intvec(0)); |
---|
| 5406 | } |
---|
| 5407 | ///////////////////////////////////////////////////////////////////////////// |
---|
[1cd62d] | 5408 | //static |
---|
[2e6eac2] | 5409 | proc inIVList(intvec iv, list li) |
---|
| 5410 | "Internal procedure - no help and no example available |
---|
| 5411 | " |
---|
| 5412 | { |
---|
| 5413 | //--- if intvec iv is contained in list li return 1, 0 otherwise |
---|
| 5414 | int i; |
---|
| 5415 | int s=size(iv); |
---|
| 5416 | for(i=1;i<=size(li);i++) |
---|
| 5417 | { |
---|
| 5418 | if(typeof(li[i])!="intvec"){ERROR("Not integer vector in the list");} |
---|
| 5419 | if(s==size(li[i])) |
---|
| 5420 | { |
---|
| 5421 | if(iv==li[i]){return(1);} |
---|
| 5422 | } |
---|
| 5423 | } |
---|
| 5424 | return(0); |
---|
| 5425 | } |
---|
| 5426 | ////////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 5427 | static proc Vielfachheit(ideal J,ideal I) |
---|
[2e6eac2] | 5428 | "Internal procedure - no help and no example available |
---|
| 5429 | " |
---|
| 5430 | { |
---|
| 5431 | //--- auxilliary procedure for addSelfInter |
---|
| 5432 | //--- compute multiplicity, suitable for the special situation there |
---|
| 5433 | int d=1; |
---|
| 5434 | int vd; |
---|
| 5435 | int c; |
---|
| 5436 | poly p; |
---|
| 5437 | ideal Ip,Jp; |
---|
| 5438 | while((d>0)||(!vd)) |
---|
| 5439 | { |
---|
| 5440 | p=randomLast(100)[nvars(basering)]; |
---|
| 5441 | Ip=std(I+ideal(p)); |
---|
| 5442 | c++; |
---|
| 5443 | if(c>20){ERROR("Vielfachheit: Dimension is wrong");} |
---|
| 5444 | d=dim(Ip); |
---|
| 5445 | vd=vdim(Ip); |
---|
| 5446 | } |
---|
| 5447 | Jp=std(J+ideal(p)); |
---|
[b1707e] | 5448 | return(vdim(Jp) div vdim(Ip)); |
---|
[2e6eac2] | 5449 | } |
---|
| 5450 | ///////////////////////////////////////////////////////////////////////////// |
---|
[f27ab81] | 5451 | static proc genus_E(list re, list iden0, intvec Eindex) |
---|
[2e6eac2] | 5452 | "Internal procedure - no help and no example available |
---|
| 5453 | " |
---|
| 5454 | { |
---|
| 5455 | int i,ge,gel,num; |
---|
| 5456 | def R=basering; |
---|
| 5457 | ring Rhelp=0,@t,dp; |
---|
| 5458 | def S=re[2][Eindex[1]]; |
---|
| 5459 | setring S; |
---|
| 5460 | def Sh=S+Rhelp; |
---|
| 5461 | //---------------------------------------------------------------------------- |
---|
| 5462 | //--- The Q-component X is reducible over C, decomposes into s=num components |
---|
| 5463 | //--- X_i, we assume they have n.c. |
---|
| 5464 | //--- s*g(X_i)=g(X)+s-1. |
---|
| 5465 | //---------------------------------------------------------------------------- |
---|
| 5466 | if(defined(I2)){kill I2;} |
---|
| 5467 | ideal I2=dcE[Eindex[2]][Eindex[3]][1]; |
---|
| 5468 | num=ncols(dcE[Eindex[2]][Eindex[3]][4]); |
---|
| 5469 | setring Sh; |
---|
| 5470 | if(defined(I2)){kill I2;} |
---|
| 5471 | ideal I2=imap(S,I2); |
---|
| 5472 | I2=homog(I2,@t); |
---|
| 5473 | ge=genus(I2); |
---|
[d44974d] | 5474 | gel=(ge+(num-1)) div num; |
---|
[2e6eac2] | 5475 | if(gel*num-ge-num+1!=0){ERROR("genus_E: not divisible by num");} |
---|
| 5476 | setring R; |
---|
| 5477 | return(gel,num); |
---|
| 5478 | } |
---|
| 5479 | |
---|