1 | /**************************************** |
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2 | * Computer Algebra System SINGULAR * |
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3 | ****************************************/ |
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4 | /* $Id: khstd.cc,v 1.3 2006-09-21 16:02:20 Singular Exp $ */ |
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5 | /* |
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6 | * ABSTRACT:utils for hilbert driven kStd |
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7 | */ |
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8 | |
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9 | #include "mod2.h" |
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10 | #include "structs.h" |
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11 | #include "febase.h" |
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12 | #include "polys.h" |
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13 | #include "intvec.h" |
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14 | #include "kutil.h" |
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15 | #include "stairc.h" |
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16 | #include "kstd1.h" |
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17 | #include "khstd.h" |
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18 | |
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19 | |
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20 | /*2 |
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21 | * compare the given hilbert series with the current one, |
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22 | * delete not needed pairs (if possible) |
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23 | */ |
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24 | void khCheck( ideal Q, intvec *w, intvec *hilb, int &eledeg, int &count, |
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25 | kStrategy strat) |
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26 | /* ideal S=strat->Shdl, poly p=strat->P.p */ |
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27 | /* |
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28 | * compute the number eledeg of elements with a degree >= deg(p) going into kStd, |
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29 | * p is already in S and for all further q going into S yields deg(q) >= deg(p), |
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30 | * the real computation is only done if the degree has changed, |
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31 | * then we have eledeg == 0 on this degree and we make: |
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32 | * - compute the Hilbert series newhilb from S |
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33 | * (hilb is the final Hilbert series) |
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34 | * - compute the eledeg from newhilb-hilb for the first degree deg with |
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35 | * newhilb-hilb != 0 |
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36 | * (Remark: consider the Hilbert series with coeff. up to infinity) |
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37 | * - clear the set L for degree < deg |
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38 | * the number count is only for statistics (in the caller initialise count = 0), |
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39 | * in order to get a first computation, initialise eledeg = 1 in the caller. |
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40 | * The weights w are needed in the module case, otherwise NULL. |
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41 | */ |
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42 | { |
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43 | intvec *newhilb; |
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44 | int deg,l,ln,mw; |
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45 | pFDegProc degp; |
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46 | |
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47 | eledeg--; |
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48 | if (eledeg == 0) |
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49 | { |
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50 | degp=pFDeg; |
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51 | // if weights for variables were given to std computations, |
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52 | // then pFDeg == degp == kHomModDeg (see kStd) |
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53 | if ((degp!=kModDeg) && (degp!=kHomModDeg)) degp=pTotaldegree; |
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54 | // degp = pWDegree; |
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55 | l = hilb->length()-1; |
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56 | mw = (*hilb)[l]; |
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57 | newhilb = hHstdSeries(strat->Shdl,w,strat->kHomW,Q,strat->tailRing); |
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58 | ln = newhilb->length()-1; |
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59 | deg = degp(strat->P.p,currRing)-mw; |
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60 | loop // compare the series in degree deg, try to increase deg ----------- |
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61 | { |
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62 | if (deg < ln) // deg may be out of range |
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63 | { |
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64 | if (deg < l) |
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65 | eledeg = (*newhilb)[deg]-(*hilb)[deg]; |
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66 | else |
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67 | eledeg = (*newhilb)[deg]; |
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68 | } |
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69 | else |
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70 | { |
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71 | if (deg < l) |
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72 | eledeg = -(*hilb)[deg]; |
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73 | else // we have newhilb = hilb |
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74 | { |
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75 | while (strat->Ll>=0) |
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76 | { |
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77 | count++; |
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78 | if(TEST_OPT_PROT) |
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79 | { |
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80 | PrintS("h"); |
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81 | mflush(); |
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82 | } |
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83 | deleteInL(strat->L,&strat->Ll,strat->Ll,strat); |
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84 | } |
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85 | delete newhilb; |
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86 | return; |
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87 | } |
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88 | } |
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89 | if (eledeg > 0) // elements to delete |
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90 | break; |
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91 | else if (eledeg <0) // strange....see bug_43 |
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92 | return; |
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93 | deg++; |
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94 | } /* loop */ |
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95 | delete newhilb; |
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96 | while ((strat->Ll>=0) && (degp(strat->L[strat->Ll].p,currRing)-mw < deg)) // the essential step |
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97 | { |
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98 | count++; |
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99 | if(TEST_OPT_PROT) |
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100 | { |
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101 | PrintS("h"); |
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102 | mflush(); |
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103 | } |
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104 | deleteInL(strat->L,&strat->Ll,strat->Ll,strat); |
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105 | } |
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106 | } |
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107 | } |
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