1 | ////////////////////////////////////////////////////////////////////////////// |
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2 | version="$Id$"; |
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3 | category="Miscellaneous"; |
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4 | info=" |
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5 | LIBRARY: standard.lib Procedures which are always loaded at Start-up |
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6 | |
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7 | PROCEDURES: |
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8 | stdfglm(ideal[,ord]) standard basis of ideal via fglm [and ordering ord] |
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9 | stdhilb(ideal[,h]) Hilbert driven Groebner basis of ideal |
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10 | groebner(ideal,...) standard basis using a heuristically chosen method |
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11 | res(ideal/module,[i]) free resolution of ideal or module |
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12 | sprintf(fmt,...) returns fomatted string |
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13 | fprintf(link,fmt,..) writes formatted string to link |
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14 | printf(fmt,...) displays formatted string |
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15 | weightKB(stc,dd,vl) degree dd part of a kbase w.r.t. some weigths |
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16 | qslimgb(i) computes a standard basis with slimgb in a qring |
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17 | par2varRing([i]) create a ring making pars to vars, together with i |
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18 | datetime() return date and time as a string |
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19 | |
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20 | "; |
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21 | //AUXILIARY PROCEDURES: |
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22 | // hilbRing([i]) ring for computing the (weighted) hilbert series |
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23 | // quotientList(L,...) ringlist for creating a correct quotient ring |
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24 | |
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25 | ////////////////////////////////////////////////////////////////////////////// |
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26 | |
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27 | proc stdfglm (ideal i, list #) |
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28 | "SYNTAX: @code{stdfglm (} ideal_expression @code{)} @* |
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29 | @code{stdfglm (} ideal_expression@code{,} string_expression @code{)} |
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30 | TYPE: ideal |
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31 | PURPOSE: computes the standard basis of the ideal in the basering |
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32 | via @code{fglm} from the ordering given as the second argument |
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33 | to the ordering of the basering. If no second argument is given, |
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34 | \"dp\" is used. The standard basis for the given ordering (resp. for |
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35 | \"dp\") is computed via the command groebner except if a further |
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36 | argument \"std\" or \"slimgb\" is given in which case std resp. |
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37 | slimgb is used. |
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38 | SEE ALSO: fglm, groebner, std, slimgb, stdhilb |
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39 | KEYWORDS: fglm |
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40 | EXAMPLE: example stdfglm; shows an example" |
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41 | { |
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42 | string os; |
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43 | int s = size(#); |
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44 | def P= basering; |
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45 | string algorithm; |
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46 | int ii; |
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47 | for( ii=1; ii<=s; ii++) |
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48 | { |
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49 | if ( typeof(#[ii])== "string" ) |
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50 | { |
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51 | if ( #[ii]=="std" || #[ii]=="slimgb" ) |
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52 | { |
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53 | algorithm = #[ii]; |
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54 | # = delete(#,ii); |
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55 | s--; |
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56 | ii--; |
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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 | if((s > 0) && (typeof(#[1]) == "string")) |
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62 | { |
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63 | os = #[1]; |
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64 | ideal Qideal = ideal(P); |
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65 | int sQ = size(Qideal); |
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66 | int sM = size(minpoly); |
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67 | if ( sM!=0 ) |
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68 | { |
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69 | string mpoly = string(minpoly); |
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70 | } |
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71 | if (sQ!=0 ) |
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72 | { |
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73 | execute("ring Rfglm=("+charstr(P)+"),("+varstr(P)+"),"+os+";"); |
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74 | ideal Qideal = fetch(P,Qideal); |
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75 | qring Pfglm = groebner(Qideal,"std","slimgb"); |
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76 | } |
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77 | else |
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78 | { |
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79 | execute("ring Pfglm=("+charstr(P)+"),("+varstr(P)+"),"+os+";"); |
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80 | } |
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81 | if ( sM!=0 ) |
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82 | { |
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83 | execute("minpoly="+mpoly+";"); |
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84 | } |
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85 | } |
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86 | else |
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87 | { |
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88 | list BRlist = ringlist(P); |
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89 | int nvarP = nvars(P); |
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90 | intvec w; //for ringweights of basering P |
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91 | int k; |
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92 | for(k=1; k <= nvarP; k++) |
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93 | { |
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94 | w[k]=deg(var(k)); |
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95 | } |
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96 | |
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97 | BRlist[3] = list(); |
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98 | if( s==0 or (typeof(#[1]) != "string") ) |
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99 | { |
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100 | if( w==1 ) |
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101 | { |
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102 | BRlist[3][1]=list("dp",w); |
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103 | } |
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104 | else |
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105 | { |
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106 | BRlist[3][1]=list("wp",w); |
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107 | } |
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108 | BRlist[3][2]=list("C",intvec(0)); |
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109 | def Pfglm = ring(quotientList(BRlist)); |
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110 | setring Pfglm; |
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111 | } |
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112 | } |
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113 | ideal i = fetch(P,i); |
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114 | |
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115 | intvec opt = option(get); //save options |
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116 | option(redSB); |
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117 | if (size(algorithm) > 0) |
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118 | { |
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119 | i = groebner(i,algorithm); |
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120 | } |
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121 | else |
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122 | { |
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123 | i = groebner(i); |
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124 | } |
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125 | option(set,opt); |
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126 | setring P; |
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127 | return (fglm(Pfglm,i)); |
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128 | } |
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129 | example |
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130 | { "EXAMPLE:"; echo = 2; |
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131 | ring r = 0,(x,y,z),lp; |
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132 | ideal i = y3+x2,x2y+x2,x3-x2,z4-x2-y; |
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133 | stdfglm(i); //uses fglm from "dp" (with groebner) to "lp" |
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134 | stdfglm(i,"std"); //uses fglm from "dp" (with std) to "lp" |
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135 | |
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136 | ring s = (0,x),(y,z,u,v),lp; |
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137 | minpoly = x2+1; |
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138 | ideal i = u5-v4,zv-u2,zu3-v3,z2u-v2,z3-uv,yv-zu,yu-z2,yz-v,y2-u,u-xy2; |
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139 | weight(i); |
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140 | stdfglm(i,"(a(2,3,4,5),dp)"); //uses fglm from "(a(2,3,4,5),dp)" to "lp" |
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141 | } |
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142 | |
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143 | ///////////////////////////////////////////////////////////////////////////// |
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144 | |
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145 | proc stdhilb(i,list #) |
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146 | "SYNTAX: @code{stdhilb (} ideal_expression @code{)} @* |
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147 | @code{stdhilb (} module_expression @code{)} @* |
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148 | @code{stdhilb (} ideal_expression, intvec_expression @code{)}@* |
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149 | @code{stdhilb (} module_expression, intvec_expression @code{)}@* |
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150 | @code{stdhilb (} ideal_expression@code{,} list of string_expressions, |
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151 | and intvec_expression @code{)} @* |
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152 | TYPE: type of the first argument |
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153 | PURPOSE: Compute a Groebner basis of the ideal/module in the basering by |
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154 | using the Hilbert driven Groebner basis algorithm. |
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155 | If an argument of type string, stating @code{\"std\"} resp. @code{\"slimgb\"}, |
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156 | is given, the standard basis computation uses @code{std} or |
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157 | @code{slimgb}, otherwise a heuristically chosen method (default)@* |
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158 | If an optional second argument w of type intvec is given, w is used |
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159 | as variable weights. If w is not given, it is computed as w[i] = |
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160 | deg(var(i)). If the ideal is homogeneous w.r.t. w then the |
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161 | Hilbert series is computed w.r.t. to these weights. |
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162 | THEORY: If the ideal is not homogeneous compute first a Groebner basis |
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163 | of the homogenization [w.r.t. the weights w] of the ideal/module, |
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164 | then the Hilbert function and, finally, a Groebner basis in the |
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165 | original ring by using the computed Hilbert function. If the given |
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166 | w does not coincide with the variable weights of the basering, the |
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167 | result may not be a groebner basis in the original ring. |
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168 | NOTE: 'Homogeneous' means weighted homogeneous with respect to the weights |
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169 | w[i] of the variables var(i) of the basering. Parameters are not |
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170 | converted to variables. |
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171 | SEE ALSO: stdfglm, std, slimgb, groebner |
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172 | KEYWORDS: Hilbert function |
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173 | EXAMPLE: example stdhilb; shows an example" |
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174 | { |
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175 | |
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176 | //--------------------- save data from basering -------------------------- |
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177 | def P=basering; |
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178 | int nr; |
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179 | if (typeof(i)=="ideal") { nr=1;} |
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180 | else { nr= nrows(i); } //nr=1 if i is an ideal |
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181 | ideal Qideal = ideal(P); //defining the quotient ideal if P is a qring |
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182 | int was_qring; //remembers if basering was a qring |
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183 | int is_homog =homog(i); //check for homogeneity of i and Qideal |
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184 | if (size(Qideal) > 0) |
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185 | { |
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186 | was_qring = 1; |
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187 | } |
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188 | |
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189 | // save ordering of basering P for later use |
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190 | list ord_P = ringlist(P)[3]; //ordering of basering in ringlist |
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191 | string ordstr_P = ordstr(P); //ordering of basering as string |
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192 | int nvarP = nvars(P); |
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193 | |
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194 | //save options: |
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195 | intvec gopt = option(get); |
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196 | int p_opt; |
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197 | string s_opt = option(); |
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198 | if (find(s_opt, "prot")) { p_opt = 1; } |
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199 | |
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200 | //-------------------- check the given method and weights --------------------- |
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201 | //Note: stdhilb is used in elim where it is applied to an elimination ordering |
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202 | //a(1..1,0..0),wp(w). In such a ring deg(var(k)=0 for all vars corresponding to |
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203 | //0 in a(1..1,0..0), hence we cannot identify w via w[k] = deg(var(k)); |
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204 | //Therefore hilbstd has the option to give ringweights. |
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205 | |
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206 | int k; |
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207 | string method; |
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208 | for (k=1; k<=size(#); k++) |
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209 | { |
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210 | if (typeof(#[k]) == "intvec") |
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211 | { |
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212 | intvec w = #[k]; //given ringweights of basering P |
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213 | } |
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214 | if (typeof(#[k]) == "string") |
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215 | { |
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216 | method = method + "," + #[k]; |
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217 | } |
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218 | } |
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219 | |
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220 | if ( defined(w)!=voice ) |
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221 | { |
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222 | intvec w; |
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223 | for(k=nvarP; k>=1; k--) |
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224 | { |
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225 | w[k] = deg(var(k)); //compute ring weights |
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226 | } |
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227 | } |
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228 | |
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229 | |
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230 | if (npars(P) > 0) //clear denominators of parameters |
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231 | { |
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232 | for( k=ncols(i); k>0; k-- ) |
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233 | { |
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234 | i[k]=cleardenom(i[k]); |
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235 | } |
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236 | } |
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237 | |
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238 | //---------- exclude cases to which stdhilb should no be applied ---------- |
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239 | //Note that quotient ideal of qring must be homogeneous too |
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240 | |
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241 | int neg=1-attrib (P,"global"); |
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242 | |
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243 | if( //find(ordstr_P,"s") ||// covered by neg |
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244 | find(ordstr_P,"M") || neg ) |
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245 | { |
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246 | // if( defined(hi) && is_homog ) |
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247 | // { |
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248 | // if (p_opt){"std with given Hilbert function in basering";} |
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249 | // return( std(i,hi,w) ); |
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250 | //### here we would need Hibert-Samuel function |
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251 | // } |
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252 | |
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253 | if (p_opt) |
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254 | {"//-- stdhilb not implemented, we use std in ring:"; string(P);} |
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255 | return( std(i) ); |
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256 | } |
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257 | |
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258 | //------------------------ change to hilbRing ---------------------------- |
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259 | //The ground field of P and Philb coincide, Philb has an extra variable |
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260 | //@ or @(k). Philb is no qring and the predefined ideal/module Id(1) in |
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261 | //Philb is homogeneous (it is the homogenized i w.r.t. @ or @(k)) |
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262 | //Parameters of P are not converted in Philb |
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263 | //Philb has only 1 block dp or wp(w) |
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264 | |
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265 | list hiRi = hilbRing(i,w); |
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266 | intvec W = hiRi[2]; |
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267 | def Philb = hiRi[1]; |
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268 | setring Philb; |
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269 | |
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270 | //-------- compute Hilbert series of homogenized ideal in Philb --------- |
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271 | //There are three cases |
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272 | |
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273 | string algorithm; //possibilities: std, slimgb, stdorslimgb |
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274 | //define algorithm: |
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275 | if( find(method,"std") && !find(method,"slimgb") ) |
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276 | { |
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277 | algorithm = "std"; |
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278 | } |
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279 | if( find(method,"slimgb") && !find(method,"std") ) |
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280 | { |
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281 | algorithm = "slimgb"; |
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282 | } |
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283 | if( find(method,"std") && find(method,"slimgb") || |
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284 | (!find(method,"std") && !find(method,"slimgb")) ) |
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285 | { |
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286 | algorithm = "stdorslimgb"; |
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287 | } |
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288 | |
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289 | //### geaendert Dez08: es wird std(Id(1)) statt Id(1) aus Philb nach Phelp |
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290 | // weitergegeben fuer hilbertgetriebenen std |
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291 | |
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292 | if (( algorithm=="std" || ( algorithm=="stdorslimgb" && char(P)>0 ) ) |
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293 | && (defined(hi)!=voice)) |
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294 | { |
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295 | if (p_opt) {"compute hilbert series with std in ring " + string(Philb); |
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296 | "weights used for hilbert series:",W;} |
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297 | Id(1) = std(Id(1)); |
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298 | intvec hi = hilb( Id(1),1,W ); |
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299 | } |
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300 | if (( algorithm=="slimgb" || ( algorithm=="stdorslimgb" && char(P)==0 ) ) |
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301 | && (defined(hi)!=voice)) |
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302 | { |
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303 | if (p_opt) {"compute hilbert series with slimgb in ring " + string(Philb); |
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304 | "weights used for hilbert series:",W;} |
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305 | Id(1) = qslimgb(Id(1)); |
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306 | intvec hi = hilb( Id(1),1,W ); |
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307 | } |
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308 | |
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309 | //-------------- we need another intermediate ring Phelp ---------------- |
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310 | //In Phelp we change only the ordering from Philb (otherwise it coincides |
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311 | //with Philb). Phelp has in addition to P an extra homogenizing variable |
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312 | //with name @ (resp. @(i) if @ and @(1), ..., @(i-1) are defined) with |
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313 | //ordering an extra last block dp(1). |
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314 | //Phelp has the same ordering as P on common variables. In Phelp |
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315 | //a quotient ideal from P is added to the input |
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316 | |
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317 | list BRlist = ringlist(Philb); |
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318 | BRlist[3] = list(); |
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319 | int so = size(ord_P); |
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320 | if( ord_P[so][1] =="c" || ord_P[so][1] =="C" ) |
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321 | { |
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322 | list moduleord = ord_P[so]; |
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323 | so = so-1; |
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324 | } |
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325 | for (k=1; k<=so; k++) |
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326 | { |
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327 | BRlist[3][k] = ord_P[k]; |
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328 | } |
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329 | |
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330 | BRlist[3][so+1] = list("dp",1); |
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331 | w = w,1; |
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332 | |
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333 | if( defined(moduleord)==voice ) |
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334 | { |
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335 | BRlist[3][so+2] = moduleord; |
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336 | } |
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337 | |
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338 | //--- change to extended ring Phelp and compute std with hilbert series ---- |
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339 | def Phelp = ring(quotientList(BRlist)); |
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340 | setring Phelp; |
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341 | def i = imap(Philb, Id(1)); |
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342 | kill Philb; |
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343 | |
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344 | // compute std with Hilbert series |
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345 | option(redThrough); |
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346 | if (w == 1) |
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347 | { |
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348 | if (p_opt){ "std with hilb in " + string(Phelp);} |
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349 | i = std(i, hi); |
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350 | } |
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351 | else |
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352 | { |
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353 | if(p_opt){"std with weighted hilb in "+string(Phelp);} |
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354 | i = std(i, hi, w); |
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355 | } |
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356 | |
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357 | //-------------------- go back to original ring --------------------------- |
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358 | //The main computation is done. Do not forget to simplfy before maping. |
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359 | |
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360 | // subst 1 for homogenizing var |
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361 | if ( p_opt ) { "dehomogenization"; } |
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362 | i = subst(i, var(nvars(basering)), 1); |
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363 | |
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364 | if (p_opt) { "simplification"; } |
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365 | i= simplify(i,34); |
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366 | |
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367 | setring P; |
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368 | if (p_opt) { "imap to ring "+string(P); } |
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369 | i = imap(Phelp,i); |
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370 | kill Phelp; |
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371 | if( was_qring ) |
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372 | { |
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373 | i = NF(i,std(0)); |
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374 | } |
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375 | i = simplify(i,34); |
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376 | // compute reduced SB |
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377 | if (find(s_opt, "redSB") > 0) |
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378 | { |
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379 | if (p_opt) { "//interreduction"; } |
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380 | i=interred(i); |
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381 | } |
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382 | attrib(i, "isSB", 1); |
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383 | option(set,gopt); |
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384 | return (i); |
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385 | } |
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386 | example |
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387 | { "EXAMPLE:"; echo = 2; |
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388 | ring r = 0,(x,y,z),lp; |
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389 | ideal i = y3+x2,x2y+x2z2,x3-z9,z4-y2-xz; |
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390 | ideal j = stdhilb(i); j; |
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391 | |
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392 | ring r1 = 0,(x,y,z),wp(3,2,1); |
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393 | ideal i = y3+x2,x2y+x2z2,x3-z9,z4-y2-xz; //ideal is homogeneous |
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394 | ideal j = stdhilb(i,"std"); j; |
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395 | //this is equivalent to: |
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396 | intvec v = hilb(std(i),1); |
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397 | ideal j1 = std(i,v,intvec(3,2,1)); j1; |
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398 | |
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399 | size(NF(j,j1))+size(NF(j1,j)); //j and j1 define the same ideal |
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400 | } |
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401 | |
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402 | /////////////////////////////////////////////////////////////////////////////// |
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403 | proc quotientList (list RL, list #) |
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404 | "SYNTAX: @code{quotientList (} list_expression @code{)} @* |
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405 | @code{quotientList (} list_expression @code{,} string_expression@code{)} |
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406 | TYPE: list |
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407 | PURPOSE: define a ringlist, say QL, of the first argument, say RL, which is |
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408 | assumed to be the ringlist of a qring, but where the quotient ideal |
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409 | RL[4] is not a standard basis with respect to the given monomial |
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410 | order in RL[3]. Then QL will be obtained from RL just by replacing |
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411 | RL[4] by a standard of it with respect to this order. RL itself |
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412 | will be returnd if size(RL[4]) <= 1 (in which case it is known to be |
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413 | a standard basis w.r.t. any ordering) or if a second argument |
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414 | \"isSB\" of type string is given. |
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415 | NOTE: the command ring(quotientList(RL)) defines a quotient ring correctly |
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416 | and should be used instead of ring(RL) if the quotient ideal RL[4] |
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417 | is not (or not known to be) a standard basis with respect to the |
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418 | monomial ordering specified in RL[3]. |
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419 | SEE ALSO: ringlist, ring |
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420 | EXAMPLE: example quotientList; shows an example" |
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421 | { |
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422 | def P = basering; |
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423 | if( size(#) > 0 ) |
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424 | { |
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425 | if ( #[1] == "isSB") |
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426 | { |
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427 | return (RL); |
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428 | } |
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429 | } |
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430 | ideal Qideal = RL[4]; //##Achtung: falls basering Nullteiler hat, kann |
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431 | //die SB eines Elements mehrere Elemente enthalten |
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432 | if( size(Qideal) <= 0) |
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433 | { |
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434 | return (RL); |
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435 | } |
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436 | |
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437 | RL[4] = ideal(0); |
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438 | def Phelp = ring(RL); |
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439 | setring Phelp; |
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440 | ideal Qideal = groebner(fetch(P,Qideal)); |
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441 | setring P; |
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442 | RL[4]=fetch(Phelp,Qideal); |
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443 | return (RL); |
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444 | } |
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445 | example |
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446 | { "EXAMPLE:"; echo = 2; |
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447 | ring P = 0,(y,z,u,v),lp; |
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448 | ideal i = y+u2+uv3, z+uv3; //i is an lp-SB but not a dp_SB |
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449 | qring Q = std(i); |
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450 | list LQ = ringlist(Q); |
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451 | LQ[3][1][1]="dp"; |
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452 | def Q1 = ring(quotientList(LQ)); |
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453 | setring Q1; |
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454 | Q1; |
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455 | |
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456 | setring Q; |
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457 | ideal q1 = uv3+z, u2+y-z, yv3-zv3-zu; //q1 is a dp-standard basis |
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458 | LQ[4] = q1; |
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459 | def Q2 = ring(quotientList(LQ,"isSB")); |
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460 | setring Q2; |
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461 | Q2; |
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462 | } |
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463 | |
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464 | /////////////////////////////////////////////////////////////////////////////// |
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465 | proc par2varRing (list #) |
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466 | "USAGE: par2varRing([l]); l list of ideals/modules [default:l=empty list] |
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467 | RETURN: list, say L, with L[1] a ring where the parameters of the |
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468 | basering have been converted to an additional last block of |
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469 | variables, all of weight 1, and ordering dp. |
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470 | If a list l with l[i] an ideal/module is given, then |
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471 | l[i] + minpoly*freemodule(nrows(l[i])) is mapped to an ideal/module |
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472 | in L[1] with name Id(i). |
---|
473 | If the basering has no parameters then L[1] is the basering. |
---|
474 | EXAMPLE: example par2varRing; shows an example" |
---|
475 | { |
---|
476 | def P = basering; |
---|
477 | int npar = npars(P); //number of parameters |
---|
478 | int s = size(#); |
---|
479 | int ii; |
---|
480 | if ( npar == 0) |
---|
481 | { |
---|
482 | dbprint(printlevel-voice+3,"// ** no parameters, ring was not changed"); |
---|
483 | for( ii = 1; ii <= s; ii++) |
---|
484 | { |
---|
485 | def Id(ii) = #[ii]; |
---|
486 | export (Id(ii)); |
---|
487 | } |
---|
488 | return(list(P)); |
---|
489 | } |
---|
490 | |
---|
491 | list rlist = ringlist(P); |
---|
492 | list parlist = rlist[1]; |
---|
493 | rlist[1] = parlist[1]; |
---|
494 | poly Minpoly = minpoly; //check for minpoly: |
---|
495 | int sm = size(Minpoly); |
---|
496 | |
---|
497 | //now create new ring |
---|
498 | for( ii = 1; ii <= s; ii++) |
---|
499 | { |
---|
500 | def Id(ii) = #[ii]; |
---|
501 | } |
---|
502 | int nvar = size(rlist[2]); |
---|
503 | int nblock = size(rlist[3]); |
---|
504 | int k; |
---|
505 | for (k=1; k<=npar; k++) |
---|
506 | { |
---|
507 | rlist[2][nvar+k] = parlist[2][k]; //change variable list |
---|
508 | } |
---|
509 | |
---|
510 | //converted parameters get one block dp. If module ordering was in front |
---|
511 | //it stays in front, otherwise it will be moved to the end |
---|
512 | intvec OW = 1:npar; |
---|
513 | if( rlist[3][nblock][1] =="c" || rlist[3][nblock][1] =="C" ) |
---|
514 | { |
---|
515 | rlist[3][nblock+1] = rlist[3][nblock]; |
---|
516 | rlist[3][nblock] = list("dp",OW); |
---|
517 | } |
---|
518 | else |
---|
519 | { |
---|
520 | rlist[3][nblock+1] = list("dp",OW); |
---|
521 | } |
---|
522 | |
---|
523 | def Ppar2var = ring(quotientList(rlist)); |
---|
524 | setring Ppar2var; |
---|
525 | if ( sm == 0 ) |
---|
526 | { |
---|
527 | for( ii = 1; ii <= s; ii++) |
---|
528 | { |
---|
529 | def Id(ii) = imap(P,Id(ii)); |
---|
530 | export (Id(ii)); |
---|
531 | } |
---|
532 | } |
---|
533 | else |
---|
534 | { |
---|
535 | if( find(option(),"prot") ){"//add minpoly to input";} |
---|
536 | poly Minpoly = imap(P,Minpoly); |
---|
537 | for( ii = 1; ii <= s; ii++) |
---|
538 | { |
---|
539 | def Id(ii) = imap(P,Id(ii)); |
---|
540 | if (typeof(Id(ii))=="module") |
---|
541 | { |
---|
542 | Id(ii) = Id(ii),Minpoly*freemodule(nrows(Id(ii))); |
---|
543 | } |
---|
544 | else |
---|
545 | { |
---|
546 | Id(ii) = Id(ii),Minpoly; |
---|
547 | } |
---|
548 | export (Id(ii)); |
---|
549 | } |
---|
550 | } |
---|
551 | list Lpar2var = Ppar2var; |
---|
552 | return(Lpar2var); |
---|
553 | } |
---|
554 | example |
---|
555 | { "EXAMPLE:"; echo = 2; |
---|
556 | ring R = (0,x),(y,z,u,v),lp; |
---|
557 | minpoly = x2+1; |
---|
558 | ideal i = x3,x2+y+z+u+v,xyzuv-1; i; |
---|
559 | def P = par2varRing(i)[1]; P; |
---|
560 | setring(P); |
---|
561 | Id(1); |
---|
562 | |
---|
563 | setring R; |
---|
564 | module m = x3*[1,1,1], (xyzuv-1)*[1,0,1]; |
---|
565 | def Q = par2varRing(m)[1]; Q; |
---|
566 | setring(Q); |
---|
567 | print(Id(1)); |
---|
568 | } |
---|
569 | |
---|
570 | ////////////////////////////////////////////////////////////////////////////// |
---|
571 | proc hilbRing ( list # ) |
---|
572 | "USAGE: hilbRing([w,l]); w = intvec, l = list of ideals/modules |
---|
573 | RETURN: list, say L: L[1] is a ring and L[2] an intvec |
---|
574 | L[1] is a ring whith an extra homogenizing variable with name @, |
---|
575 | resp. @(i) if @ and @(1), ..., @(i-1) are defined. |
---|
576 | The monomial ordering of L[1] is consists of 1 block: dp if the |
---|
577 | weights of the variables of the basering, say R, are all 1, resp. |
---|
578 | wp(w,1) wehre w is either given or the intvec of weights of the |
---|
579 | variables of R, i.e. w[k]=deg(var(k)). |
---|
580 | If R is a quotient ring P/Q, then L[1] is not a quotient ring but |
---|
581 | contains the ideal @Qidealhilb@, the homogenized ideal Q of P. |
---|
582 | (Parameters of R are not touched). |
---|
583 | If a list l is given with l[i] an ideal/module, then l[i] is mapped |
---|
584 | to Id(i), the homogenized l[i]+Q*freemodule(nrows(l[i]) in L[1] |
---|
585 | (Id(i) = l[i] if l[i] is already homogeneous). |
---|
586 | L[2] is the intvec (w,1). |
---|
587 | PURPOSE: Prepare a ring for computing the (weighted) hilbert series of |
---|
588 | an ideal/module with an easy monomial ordering. |
---|
589 | NOTE: For this purpose we need w[k]=deg(var(k)). However, if the ordering |
---|
590 | contains an extra weight vector a(v,0..0)) deg(var(k)) returns 0 for |
---|
591 | k being an index which is 0 in a. Therefore we must compute w |
---|
592 | beforehand and give it to hilbRing. |
---|
593 | EXAMPLE: example hilbRing; shows an example |
---|
594 | " |
---|
595 | { |
---|
596 | def P = basering; |
---|
597 | ideal Qideal = ideal(P); //defining the quotient ideal if P is a qring |
---|
598 | if( size(Qideal) != 0 ) |
---|
599 | { |
---|
600 | int is_qring =1; |
---|
601 | } |
---|
602 | list BRlist = ringlist(P); |
---|
603 | BRlist[4] = ideal(0); //kill quotient ideal in BRlist |
---|
604 | |
---|
605 | int nvarP = nvars(P); |
---|
606 | int s = size(#); |
---|
607 | int k; |
---|
608 | |
---|
609 | for(k = 1; k <= s; k++) |
---|
610 | { |
---|
611 | if ( typeof(#[k]) == "intvec" ) |
---|
612 | { |
---|
613 | intvec w = #[k]; //given weights for the variables |
---|
614 | # = delete (#,k); |
---|
615 | } |
---|
616 | } |
---|
617 | |
---|
618 | s = size(#); |
---|
619 | for(k = 1; k <= s; k++) |
---|
620 | { |
---|
621 | def Id(k) = #[k]; |
---|
622 | int nr(k) = nrows(Id(k)); |
---|
623 | } |
---|
624 | |
---|
625 | if ( defined(w)!=voice ) |
---|
626 | { |
---|
627 | intvec w; //for ringweights of basering P |
---|
628 | for(k=1; k<=nvarP; k++) |
---|
629 | { |
---|
630 | w[k]=deg(var(k)); //degree of kth variable |
---|
631 | } |
---|
632 | } |
---|
633 | //--------------------- a homogenizing variable is added ------------------ |
---|
634 | // call it @, resp. @(k) if @(1),...,@(k-1) are defined |
---|
635 | string homvar; |
---|
636 | if ( defined(@)==0 ) |
---|
637 | { |
---|
638 | homvar = "@"; |
---|
639 | } |
---|
640 | else |
---|
641 | { |
---|
642 | k=1; |
---|
643 | while( defined(@(k)) != 0 ) |
---|
644 | { |
---|
645 | k++; |
---|
646 | } |
---|
647 | homvar = "@("+string(k)+")"; |
---|
648 | } |
---|
649 | BRlist[2][nvarP+1] = homvar; |
---|
650 | w[nvarP +1]=1; |
---|
651 | |
---|
652 | //ordering is set to (dp,C) if weights of all variables are 1 |
---|
653 | //resp. to (wp(w,1),C) where w are the ringweights of basering P |
---|
654 | //homogenizing var gets weight 1: |
---|
655 | |
---|
656 | BRlist[3] = list(); |
---|
657 | BRlist[3][2]=list("C",intvec(0)); //put module ordering always last |
---|
658 | if(w==1) |
---|
659 | { |
---|
660 | BRlist[3][1]=list("dp",w); |
---|
661 | } |
---|
662 | else |
---|
663 | { |
---|
664 | BRlist[3][1]=list("wp",w); |
---|
665 | } |
---|
666 | |
---|
667 | //-------------- change ring and get ideal from previous ring --------------- |
---|
668 | def Philb = ring(quotientList(BRlist)); |
---|
669 | kill BRlist; |
---|
670 | setring Philb; |
---|
671 | if( defined(is_qring)==voice ) |
---|
672 | { |
---|
673 | ideal @Qidealhilb@ = imap(P,Qideal); |
---|
674 | if ( ! homog(@Qidealhilb@) ) |
---|
675 | { |
---|
676 | @Qidealhilb@ = homog( @Qidealhilb@, `homvar` ); |
---|
677 | } |
---|
678 | export(@Qidealhilb@); |
---|
679 | |
---|
680 | if( find(option(),"prot") ){"add quotient ideal to input";} |
---|
681 | |
---|
682 | for(k = 1; k <= s; k++) |
---|
683 | { //homogenize if necessary |
---|
684 | def Id(k) = imap(P,Id(k)); |
---|
685 | if ( ! homog(Id(k)) ) |
---|
686 | { |
---|
687 | Id(k) = homog( imap(P,Id(k)), `homvar` ); |
---|
688 | } |
---|
689 | if (typeof(Id(k))=="module") |
---|
690 | { |
---|
691 | Id(k) = Id(k),@Qidealhilb@*freemodule(nr(k)) ; |
---|
692 | } |
---|
693 | else |
---|
694 | { |
---|
695 | Id(k) = Id(k),@Qidealhilb@ ; |
---|
696 | } |
---|
697 | export(Id(k)); |
---|
698 | } |
---|
699 | } |
---|
700 | else |
---|
701 | { |
---|
702 | for(k = 1; k <= s; k++) |
---|
703 | { //homogenize if necessary |
---|
704 | def Id(k) = imap(P,Id(k)); |
---|
705 | if ( ! homog(Id(k)) ) |
---|
706 | { |
---|
707 | Id(k) = homog( imap(P,Id(k)), `homvar` ); |
---|
708 | } |
---|
709 | export(Id(k)); |
---|
710 | } |
---|
711 | } |
---|
712 | list Lhilb = Philb,w; |
---|
713 | return(Lhilb); |
---|
714 | } |
---|
715 | example |
---|
716 | { "EXAMPLE:"; echo = 2; |
---|
717 | ring R = 0,(x,y,z,u,v),lp; |
---|
718 | ideal i = x+y2+z3,xy+xv+yz+zu+uv,xyzuv-1; |
---|
719 | intvec w = 6,3,2,1,1; |
---|
720 | hilbRing(i,w); |
---|
721 | def P = hilbRing(w,i)[1]; |
---|
722 | setring P; |
---|
723 | Id(1); |
---|
724 | hilb(std(Id(1)),1); |
---|
725 | |
---|
726 | ring S = 0,(x,y,z,u,v),lp; |
---|
727 | qring T = std(x+y2+z3); |
---|
728 | ideal i = xy+xv+yz+zu+uv,xyzuv-v5; |
---|
729 | module m = i*[0,1,1] + (xyzuv-v5)*[1,1,0]; |
---|
730 | def Q = hilbRing(m)[1]; Q; |
---|
731 | setring Q; |
---|
732 | print(Id(1)); |
---|
733 | } |
---|
734 | |
---|
735 | ////////////////////////////////////////////////////////////////////////////// |
---|
736 | proc qslimgb (i) |
---|
737 | "USAGE: qslimgb(i); i ideal or module |
---|
738 | RETURN: same type as input, a standard basis of i computed with slimgb |
---|
739 | NOTE: Only as long as slimgb does not know qrings qslimgb should be used |
---|
740 | in case the basering is (possibly) a quotient ring. |
---|
741 | The quotient ideal is added to the input and slimgb is applied. |
---|
742 | EXAMPLE: example qslimgb; shows an example" |
---|
743 | { |
---|
744 | def P = basering; |
---|
745 | ideal Qideal = ideal(P); //defining the quotient ideal if P is a qring |
---|
746 | int p_opt; |
---|
747 | if( find(option(),"prot") ) |
---|
748 | { |
---|
749 | p_opt=1; |
---|
750 | } |
---|
751 | if (size(Qideal) == 0) |
---|
752 | { |
---|
753 | if (p_opt) { "slimgb in ring " + string(P); } |
---|
754 | return(slimgb(i)); |
---|
755 | } |
---|
756 | |
---|
757 | //case of a qring; since slimgb does not know qrings we |
---|
758 | //delete the quotient ideal and add it to i |
---|
759 | |
---|
760 | list BRlist = ringlist(P); |
---|
761 | BRlist[4] = ideal(0); |
---|
762 | def Phelp = ring(BRlist); |
---|
763 | kill BRlist; |
---|
764 | setring Phelp; |
---|
765 | // module case: |
---|
766 | def iq = imap(P,i); |
---|
767 | iq = iq, imap(P,Qideal)*freemodule(nrows(iq)); |
---|
768 | if (p_opt) |
---|
769 | { |
---|
770 | "slimgb in ring " + string(Phelp); |
---|
771 | "(with quotient ideal added to input)"; |
---|
772 | } |
---|
773 | iq = slimgb(iq); |
---|
774 | |
---|
775 | setring P; |
---|
776 | if (p_opt) { "//imap to original ring"; } |
---|
777 | i = imap(Phelp,iq); |
---|
778 | kill Phelp; |
---|
779 | |
---|
780 | if (find(option(),"redSB") > 0) |
---|
781 | { |
---|
782 | if (p_opt) { "//interreduction"; } |
---|
783 | i=reduce(i,std(0)); |
---|
784 | i=interred(i); |
---|
785 | } |
---|
786 | attrib(i, "isSB", 1); |
---|
787 | return (i); |
---|
788 | } |
---|
789 | example |
---|
790 | { "EXAMPLE:"; echo = 2; |
---|
791 | ring R = (0,v),(x,y,z,u),dp; |
---|
792 | qring Q = std(x2-y3); |
---|
793 | ideal i = x+y2,xy+yz+zu+u*v,xyzu*v-1; |
---|
794 | ideal j = qslimgb(i); j; |
---|
795 | |
---|
796 | module m = [x+y2,1,0], [1,1,x2+y2+xyz]; |
---|
797 | print(qslimgb(m)); |
---|
798 | } |
---|
799 | |
---|
800 | ////////////////////////////////////////////////////////////////////////////// |
---|
801 | proc groebner(def i_par, list #) |
---|
802 | "SYNTAX: @code{groebner (} ideal_expression @code{)} @* |
---|
803 | @code{groebner (} module_expression @code{)} @* |
---|
804 | @code{groebner (} ideal_expression@code{,} int_expression @code{)} @* |
---|
805 | @code{groebner (} module_expression@code{,} int_expression @code{)} @* |
---|
806 | @code{groebner (} ideal_expression@code{,} list of string_expressions |
---|
807 | @code{)} @* |
---|
808 | @code{groebner (} ideal_expression@code{,} list of string_expressions |
---|
809 | and int_expression @code{)} @* |
---|
810 | @code{groebner (} ideal_expression@code{,} int_expression @code{)} |
---|
811 | TYPE: type of the first argument |
---|
812 | PURPOSE: computes a standard basis of the first argument @code{I} |
---|
813 | (ideal or module) by a heuristically chosen method (default) |
---|
814 | or by a method specified by further arguments of type string. |
---|
815 | Possible methods are: @* |
---|
816 | - the direct methods @code{\"std\"} or @code{\"slimgb\"} without |
---|
817 | conversion, @* |
---|
818 | - conversion methods @code{\"hilb\"} or @code{\"fglm\"} where |
---|
819 | a Groebner basis is first computed with an \"easy\" ordering |
---|
820 | and then converted to the ordering of the basering by the |
---|
821 | Hilbert driven Groebner basis computation or by linear algebra. |
---|
822 | The actual computation of the Groebner basis can be |
---|
823 | specified by @code{\"std\"} or by @code{\"slimgb\"} |
---|
824 | (not for all orderings implemented). @* |
---|
825 | A further string @code{\"par2var\"} converts parameters to an extra |
---|
826 | block of variables before a Groebner basis computation (and |
---|
827 | afterwards back). |
---|
828 | @code{option(prot)} informs about the chosen method. |
---|
829 | NOTE: If an additional argument, say @code{wait}, of type int is given, |
---|
830 | then the computation runs for at most @code{wait} seconds. |
---|
831 | That is, if no result could be computed in @code{wait} seconds, |
---|
832 | then the computation is interrupted, 0 is returned, a warning |
---|
833 | message is displayed, and the global variable |
---|
834 | @code{Standard::groebner_error} is defined. |
---|
835 | This feature uses MP and hence it is available on UNIX platforms, only. |
---|
836 | HINT: Since there exists no uniform best method for computing standard |
---|
837 | bases, and since the difference in performance of a method on |
---|
838 | different examples can be huge, it is recommended to test, for hard |
---|
839 | examples, first various methods on a simplified example (e.g. use |
---|
840 | characteristic 32003 instead of 0 or substitute a subset of |
---|
841 | parameters/variables by integers, etc.). @* |
---|
842 | SEE ALSO: stdhilb, stdfglm, std, slimgb |
---|
843 | KEYWORDS: time limit on computations; MP, groebner basis computations |
---|
844 | EXAMPLE: example groebner; shows an example" |
---|
845 | |
---|
846 | { |
---|
847 | //Vorgabe einer Teilmenge aus {hilb,fglm,par2var,std,slimgb} |
---|
848 | //V1: Erste Einstellungen (Jan 2007) |
---|
849 | //V2: Aktuelle Aenderungen (Juni 2008) |
---|
850 | //--------------------------------- |
---|
851 | //0. Immer Aufruf von std unabhaengig von der Vorgabe: |
---|
852 | // gemischte Ordnungen, extra Gewichtsvektor, Matrix Ordnungen |
---|
853 | // ### Todo: extra Gewichtsvektor sollte nicht immer mit std wirken, |
---|
854 | // sondern z.B. mit "hilb" arbeiten koennen |
---|
855 | // ### Todo: es sollte ein Gewichtsvektor mitgegeben werden koennen (oder |
---|
856 | // berechnet werden), z.B. groebner(I,"hilb",w) oder groebner(I,"withWeights") |
---|
857 | // wie bei elim in elim.lib |
---|
858 | |
---|
859 | //1. Keine Vorgabe: es wirkt die aktuelle Heuristk: |
---|
860 | // - Char = p: std |
---|
861 | //V1 - Char = 0: slimgb (im qring wird Quotientenideal zum Input addiert) |
---|
862 | //V2 - Char = 0: std |
---|
863 | // - 1-Block-Ordnungen/non-commutative: direkt Aufruf von std oder slimgb |
---|
864 | // - Komplizierte Ordnungen (lp oder > 1 Block): hilb |
---|
865 | //V1 - Parameter werden grundsaetzlich nicht in Variable umgewandelt |
---|
866 | //V2 - Mehr als ein Parmeter wird zu Variable konvertiert |
---|
867 | // - fglm is keine Heuristik, da sonst vorher dim==0 peprueft werden muss |
---|
868 | |
---|
869 | //2. Vorgabe aus {std,slimgb}: es wird wo immer moeglich das Angegebene |
---|
870 | // gewaehlt (da slimgb keine Hilbertfunktion kennt, wird std verwendet). |
---|
871 | // Bei slimgb im qring, wird das Quotientenideal zum Ideal addiert. |
---|
872 | // Bei Angabe von std zusammen mit slimgb (aequivalent zur Angabe von |
---|
873 | // keinem von beidem) wirkt obige Heuristik. |
---|
874 | |
---|
875 | //3. Nichtleere Vorgabe aus {hilb,fglm,std,slimgb}: |
---|
876 | // es wird nur das Angegebene und Moegliche sowie das Notwendige verwendet |
---|
877 | // und bei Wahlmoeglickeit je nach Heuristik. |
---|
878 | // Z.B. Vorgabe von {hilb} ist aequivalent zu {hilb,std,slimgb} und es wird |
---|
879 | // hilb und nach Heuristik std oder slimgb verwendet, |
---|
880 | // (V1: aber nicht par2var) |
---|
881 | // bei Vorgabe von {hilb,slimgb} wird hilb und wo moeglich slimgb verwendet. |
---|
882 | |
---|
883 | //4. Bei Vorgabe von {par2var} wird par2var immer mit hilb und nach Heuristik |
---|
884 | // std oder slimgb verwendet. Zu Variablen konvertierte Parameter haben |
---|
885 | // extra letzten Block und Gewichte 1. |
---|
886 | |
---|
887 | def P=basering; |
---|
888 | if ((typeof(i_par)=="vector")||(typeof(i_par)=="module")||(typeof(i_par)=="matrix")) {module i=i_par;} |
---|
889 | else {ideal i=i_par; } // int, poly, number, ideal |
---|
890 | kill i_par; |
---|
891 | |
---|
892 | //----------------------- save the given method --------------------------- |
---|
893 | string method; //all given methods as a coma separated string |
---|
894 | list Method; //all given methods as a list |
---|
895 | int k; |
---|
896 | for (k=1; k<=size(#); k++) |
---|
897 | { |
---|
898 | if (typeof(#[k]) == "int") |
---|
899 | { |
---|
900 | int wait = #[k]; |
---|
901 | } |
---|
902 | if (typeof(#[k]) == "string") |
---|
903 | { |
---|
904 | method = method + "," + #[k]; |
---|
905 | Method = Method + list(#[k]); |
---|
906 | } |
---|
907 | } |
---|
908 | |
---|
909 | //======= we have an argument of type int -- try to use MPfork links ======= |
---|
910 | if ( defined(wait) == voice ) |
---|
911 | { |
---|
912 | if ( system("with", "MP") ) |
---|
913 | { |
---|
914 | int j = 10; |
---|
915 | string bs = nameof(basering); |
---|
916 | link l_fork = "MPtcp:fork"; |
---|
917 | open(l_fork); |
---|
918 | write(l_fork, quote(system("pid"))); |
---|
919 | int pid = read(l_fork); |
---|
920 | // write(l_fork, quote(groebner(eval(i)))); |
---|
921 | write(l_fork, quote(groebner(eval(i),eval(Method)))); |
---|
922 | //###Fehlermeldung: |
---|
923 | // ***dError: undef. ringorder used |
---|
924 | // occured at: |
---|
925 | |
---|
926 | // sleep in small intervalls for appr. one second |
---|
927 | if (wait > 0) |
---|
928 | { |
---|
929 | while(j < 1000000) |
---|
930 | { |
---|
931 | if (status(l_fork, "read", "ready", j)) {break;} |
---|
932 | j = j + j; |
---|
933 | } |
---|
934 | } |
---|
935 | |
---|
936 | // sleep in intervalls of one second from now on |
---|
937 | j = 1; |
---|
938 | while (j < wait) |
---|
939 | { |
---|
940 | if (status(l_fork, "read", "ready", 1000000)) {break;} |
---|
941 | j = j + 1; |
---|
942 | } |
---|
943 | |
---|
944 | if (status(l_fork, "read", "ready")) |
---|
945 | { |
---|
946 | def result = read(l_fork); |
---|
947 | if (bs != nameof(basering)) |
---|
948 | { |
---|
949 | def PP = basering; |
---|
950 | setring P; |
---|
951 | def result = imap(PP, result); |
---|
952 | kill PP; |
---|
953 | } |
---|
954 | if (defined(groebner_error)==1) |
---|
955 | { |
---|
956 | kill groebner_error; |
---|
957 | } |
---|
958 | kill l_fork; |
---|
959 | } |
---|
960 | else |
---|
961 | { |
---|
962 | ideal result; |
---|
963 | if (! defined(groebner_error)) |
---|
964 | { |
---|
965 | int groebner_error = 1; |
---|
966 | export groebner_error; |
---|
967 | } |
---|
968 | "** groebner did not finish"; |
---|
969 | j = system("sh", "kill " + string(pid)); |
---|
970 | } |
---|
971 | return (result); |
---|
972 | } |
---|
973 | else |
---|
974 | { |
---|
975 | "** groebner with a time limit on computation is not supported |
---|
976 | in this configuration"; |
---|
977 | } |
---|
978 | } |
---|
979 | |
---|
980 | //=========== we are still here -- do the actual computation ============= |
---|
981 | |
---|
982 | //--------------------- save data from basering --------------------------- |
---|
983 | poly Minpoly = minpoly; //minimal polynomial |
---|
984 | int was_minpoly; //remembers if there was a minpoly in P |
---|
985 | if (size(Minpoly) > 0) |
---|
986 | { |
---|
987 | was_minpoly = 1; |
---|
988 | } |
---|
989 | |
---|
990 | ideal Qideal = ideal(P); //defining the quotient ideal if P is a qring |
---|
991 | int was_qring; //remembers if basering was a qring |
---|
992 | //int is_homog = 1; |
---|
993 | if (size(Qideal) > 0) |
---|
994 | { |
---|
995 | was_qring = 1; |
---|
996 | //is_homog = homog(Qideal); //remembers if Qideal was homog (homog(0)=1) |
---|
997 | } |
---|
998 | list BRlist = ringlist(P); //ringlist of basering |
---|
999 | |
---|
1000 | // save ordering of basering P for later use |
---|
1001 | list ord_P = BRlist[3]; //should be available in all rings |
---|
1002 | string ordstr_P = ordstr(P); |
---|
1003 | int nvars_P = nvars(P); |
---|
1004 | int npars_P = npars(P); |
---|
1005 | intvec w; //for ringweights of basering P |
---|
1006 | for(k=1; k<=nvars_P; k++) |
---|
1007 | { |
---|
1008 | w[k]=deg(var(k)); |
---|
1009 | } |
---|
1010 | int neg=1-attrib (P,"global"); |
---|
1011 | |
---|
1012 | //save options: |
---|
1013 | intvec opt=option(get); |
---|
1014 | string s_opt = option(); |
---|
1015 | int p_opt; |
---|
1016 | if (find(s_opt, "prot")) { p_opt = 1; } |
---|
1017 | |
---|
1018 | //------------------ cases where std is always used ------------------------ |
---|
1019 | //If other methods are not implemented or do not make sense, i.e. for |
---|
1020 | //local or mixed orderings, matrix orderings, extra weight vector |
---|
1021 | //### Todo: extra weight vector should be allowed for e.g. with "hilb" |
---|
1022 | |
---|
1023 | if( //( find(ordstr_P,"s") > 0 ) || // covered by neg |
---|
1024 | ( find(ordstr_P,"M") > 0 ) || ( find(ordstr_P,"a") > 0 ) || neg ) |
---|
1025 | { |
---|
1026 | if (p_opt) { "std in basering"; } |
---|
1027 | return(std(i)); |
---|
1028 | } |
---|
1029 | |
---|
1030 | //now we have: |
---|
1031 | //ideal or module, global ordering, no matrix ordering, no extra weight vector |
---|
1032 | //The interesting cases start now. |
---|
1033 | |
---|
1034 | //------------------ classify the possible settings --------------------- |
---|
1035 | string algorithm; //possibilities: std, slimgb, stdorslimgb |
---|
1036 | string conversion; //possibilities: hilb, fglm, hilborfglm, no |
---|
1037 | string partovar; //possibilities: yes, no |
---|
1038 | string order; //possibilities: simple, !simple |
---|
1039 | string direct; //possibilities: yes, no |
---|
1040 | |
---|
1041 | //define algorithm: |
---|
1042 | if( find(method,"std") && !find(method,"slimgb") ) |
---|
1043 | { |
---|
1044 | algorithm = "std"; |
---|
1045 | } |
---|
1046 | if( find(method,"slimgb") && !find(method,"std") ) |
---|
1047 | { |
---|
1048 | algorithm = "slimgb"; |
---|
1049 | } |
---|
1050 | if( find(method,"std") && find(method,"slimgb") || |
---|
1051 | (!find(method,"std") && !find(method,"slimgb")) ) |
---|
1052 | { |
---|
1053 | algorithm = "stdorslimgb"; |
---|
1054 | } |
---|
1055 | |
---|
1056 | //define conversion: |
---|
1057 | if( find(method,"hilb") && !find(method,"fglm") ) |
---|
1058 | { |
---|
1059 | conversion = "hilb"; |
---|
1060 | } |
---|
1061 | if( find(method,"fglm") && !find(method,"hilb") ) |
---|
1062 | { |
---|
1063 | conversion = "fglm"; |
---|
1064 | } |
---|
1065 | if( find(method,"fglm") && find(method,"hilb") ) |
---|
1066 | { |
---|
1067 | conversion = "hilborfglm"; |
---|
1068 | } |
---|
1069 | if( !find(method,"fglm") && !find(method,"hilb") ) |
---|
1070 | { |
---|
1071 | conversion = "no"; |
---|
1072 | } |
---|
1073 | |
---|
1074 | //define partovar: |
---|
1075 | //if( find(method,"par2var") && npars_P > 0 ) //V1 |
---|
1076 | if( find(method,"par2var") || npars_P > 1 ) //V2 |
---|
1077 | { |
---|
1078 | partovar = "yes"; |
---|
1079 | } |
---|
1080 | else |
---|
1081 | { |
---|
1082 | partovar = "no"; |
---|
1083 | } |
---|
1084 | |
---|
1085 | //define order: |
---|
1086 | if (system("nblocks") <= 2) |
---|
1087 | { |
---|
1088 | if ( find(ordstr_P,"M")+find(ordstr_P,"lp")+find(ordstr_P,"rp") <= 0 ) |
---|
1089 | { |
---|
1090 | order = "simple"; |
---|
1091 | } |
---|
1092 | } |
---|
1093 | |
---|
1094 | //define direct: |
---|
1095 | if ( (order=="simple" && (size(method)==0)) || |
---|
1096 | (size(BRlist)>4) || |
---|
1097 | (order=="simple" && (method==",par2var" && npars_P==0 )) || |
---|
1098 | (conversion=="no" && partovar=="no" && |
---|
1099 | (algorithm=="std" || algorithm=="slimgb" || |
---|
1100 | (find(method,"std") && find(method,"slimgb")) ) ) ) |
---|
1101 | { |
---|
1102 | direct = "yes"; |
---|
1103 | } |
---|
1104 | else |
---|
1105 | { |
---|
1106 | direct = "no"; |
---|
1107 | } |
---|
1108 | |
---|
1109 | //order=="simple" means that the ordering of the variables consists of one |
---|
1110 | //block which is not a matrix ordering and not a lexicographical ordering. |
---|
1111 | //(Note:Singular counts always least 2 blocks, one is for module component): |
---|
1112 | //Call a method "direct" if conversion=="no" && partovar="no" which means |
---|
1113 | //that we apply std or slimgb dircet in the basering (exception |
---|
1114 | //as long as slimgb does not know qrings: in a qring of a ring P |
---|
1115 | //the ideal Qideal is added to the ideal and slimgb is applied in P). |
---|
1116 | //We apply a direct method if we have a simple monomial ordering, if no |
---|
1117 | //conversion (fglm or hilb) is specified and if the parameters shall |
---|
1118 | //not be made to variables |
---|
1119 | //BRlist (=ringlist of basering) > 4 if the basering is non-commutative |
---|
1120 | //---------------------------- direct methods ----------------------------- |
---|
1121 | if ( direct == "yes" ) |
---|
1122 | { |
---|
1123 | //if ( algorithm=="std" || (algorithm=="stdorslimgb" && char(P)>0) ) //V1 |
---|
1124 | if ( algorithm=="std" || (algorithm=="stdorslimgb") ) //V2 |
---|
1125 | { |
---|
1126 | if (p_opt) { "std in " + string(P); } |
---|
1127 | return(std(i)); |
---|
1128 | } |
---|
1129 | //if( algorithm=="slimgb" || (algorithm=="stdorslimgb" && char(P)==0)) //V1 |
---|
1130 | if ( algorithm=="slimgb" ) //V2 |
---|
1131 | { |
---|
1132 | return(qslimgb(i)); |
---|
1133 | } |
---|
1134 | } |
---|
1135 | |
---|
1136 | //--------------------------- indirect methods ----------------------------- |
---|
1137 | //indirect methods are methods where a conversion is used with a ring change |
---|
1138 | //We are in the following situation: |
---|
1139 | //direct=="no" (i.e. "hilb" or "fglm" or "par2var" is given) |
---|
1140 | //or no method is given and we have a complicated monomial ordering |
---|
1141 | //V1: "par2var" is not a default strategy, it must be explicitely |
---|
1142 | //given in order to be performed. |
---|
1143 | //V2: "par2var" is a default strategy if there are more than 1 parameters |
---|
1144 | |
---|
1145 | //------------ case where no parameters are made to variables ------------- |
---|
1146 | if ( partovar == "no" && conversion == "hilb" |
---|
1147 | || (partovar == "no" && conversion == "fglm" ) |
---|
1148 | || (partovar == "no" && conversion == "hilborfglm" ) |
---|
1149 | || (partovar == "no" && conversion == "no" && direct == "no") ) |
---|
1150 | //last case: heuristic |
---|
1151 | { |
---|
1152 | if ( conversion=="fglm" ) |
---|
1153 | { |
---|
1154 | //if ( algorithm=="std" || (algorithm=="stdorslimgb" && char(P)>0) ) //V1 |
---|
1155 | if ( algorithm=="std" || (algorithm=="stdorslimgb") ) //V2 |
---|
1156 | { |
---|
1157 | return (stdfglm(i,"std")); |
---|
1158 | } |
---|
1159 | //if(algorithm=="slimgb" || (algorithm=="stdorslimgb" && char(P)==0))//V1 |
---|
1160 | if( algorithm=="slimgb" ) //V2 |
---|
1161 | { |
---|
1162 | return (stdfglm(i,"slimgb")); |
---|
1163 | } |
---|
1164 | } |
---|
1165 | else |
---|
1166 | { |
---|
1167 | //if ( algorithm=="std" || (algorithm=="stdorslimgb" && char(P)>0) )//V1 |
---|
1168 | if ( algorithm=="std" || (algorithm=="stdorslimgb" ) ) //V2 |
---|
1169 | { |
---|
1170 | return (stdhilb(i,"std")); |
---|
1171 | } |
---|
1172 | //if(algorithm=="slimgb" || (algorithm=="stdorslimgb" && char(P)==0))//V1 |
---|
1173 | if ( algorithm=="slimgb" ) //V2 |
---|
1174 | { |
---|
1175 | return (stdhilb(i,"slimgb")); |
---|
1176 | } |
---|
1177 | } |
---|
1178 | } |
---|
1179 | |
---|
1180 | //------------ case where parameters are made to variables ---------------- |
---|
1181 | //define a ring Phelp via par2varRing in which the parameters are variables |
---|
1182 | |
---|
1183 | else |
---|
1184 | { |
---|
1185 | // reset options |
---|
1186 | option(none); |
---|
1187 | // turn on options prot, mem, redSB, intStrategy if previously set |
---|
1188 | if ( find(s_opt, "prot") ) |
---|
1189 | { option(prot); } |
---|
1190 | if ( find(s_opt, "mem") ) |
---|
1191 | { option(mem); } |
---|
1192 | if ( find(s_opt, "redSB") ) |
---|
1193 | { option(redSB); } |
---|
1194 | if ( find(s_opt, "intStrategy") ) |
---|
1195 | { option(intStrategy); } |
---|
1196 | |
---|
1197 | //first clear denominators of parameters |
---|
1198 | if (npars_P > 0) |
---|
1199 | { |
---|
1200 | for( k=ncols(i); k>0; k-- ) |
---|
1201 | { i[k]=cleardenom(i[k]); } |
---|
1202 | } |
---|
1203 | |
---|
1204 | def Phelp = par2varRing(i)[1]; //minpoly is mapped with i |
---|
1205 | setring Phelp; |
---|
1206 | def i = Id(1); |
---|
1207 | //is_homog = homog(i); |
---|
1208 | |
---|
1209 | //If parameters are converted to ring variables, they appear in an extra |
---|
1210 | //block. Therefore we use always hilb for this block ordering: |
---|
1211 | if ( conversion=="fglm" ) |
---|
1212 | { |
---|
1213 | i = (stdfglm(i)); //only uesful for 1 parameter with minpoly |
---|
1214 | } |
---|
1215 | else |
---|
1216 | { |
---|
1217 | //if ( algorithm=="std" || (algorithm=="stdorslimgb" && char(P)>0) )//V1 |
---|
1218 | if ( algorithm=="std" || (algorithm=="stdorslimgb" )) //V2 |
---|
1219 | { |
---|
1220 | i = stdhilb(i,"std"); |
---|
1221 | } |
---|
1222 | //if(algorithm=="slimgb" || (algorithm=="stdorslimgb" && char(P)==0))//V1 |
---|
1223 | if ( algorithm=="slimgb" ) //V2 |
---|
1224 | { |
---|
1225 | i = stdhilb(i,"slimgb"); |
---|
1226 | } |
---|
1227 | } |
---|
1228 | } |
---|
1229 | |
---|
1230 | //-------------------- go back to original ring --------------------------- |
---|
1231 | //The main computation is done. However, the SB coming from a ring with |
---|
1232 | //extra variables is in general too big. We simplify it before mapping it |
---|
1233 | //to the basering. |
---|
1234 | |
---|
1235 | if (p_opt) { "//simplification"; } |
---|
1236 | |
---|
1237 | if (was_minpoly) |
---|
1238 | { |
---|
1239 | ideal Minpoly = imap(P,Minpoly); |
---|
1240 | attrib(Minpoly,"isSB",1); |
---|
1241 | i = simplify(NF(i,Minpoly),2); |
---|
1242 | } |
---|
1243 | |
---|
1244 | def Li = lead(i); |
---|
1245 | setring P; |
---|
1246 | def Li = imap(Phelp,Li); |
---|
1247 | Li = simplify(Li,32); |
---|
1248 | intvec vi; |
---|
1249 | for (k=1; k<=ncols(Li); k++) |
---|
1250 | { |
---|
1251 | vi[k] = Li[k]==0; |
---|
1252 | } |
---|
1253 | |
---|
1254 | setring Phelp; |
---|
1255 | for (k=1; k<=size(i) ;k++) |
---|
1256 | { |
---|
1257 | if(vi[k]==1) |
---|
1258 | { |
---|
1259 | i[k]=0; |
---|
1260 | } |
---|
1261 | } |
---|
1262 | i = simplify(i,2); |
---|
1263 | |
---|
1264 | setring P; |
---|
1265 | if (p_opt) { "//imap to original ring"; } |
---|
1266 | i = imap(Phelp,i); |
---|
1267 | kill Phelp; |
---|
1268 | i = simplify(i,34); |
---|
1269 | |
---|
1270 | // clean-up time |
---|
1271 | option(set, opt); |
---|
1272 | if (find(s_opt, "redSB") > 0) |
---|
1273 | { |
---|
1274 | if (p_opt) { "//interreduction"; } |
---|
1275 | i=interred(i); |
---|
1276 | } |
---|
1277 | attrib(i, "isSB", 1); |
---|
1278 | return (i); |
---|
1279 | } |
---|
1280 | example |
---|
1281 | { "EXAMPLE: "; echo=2; |
---|
1282 | intvec opt = option(get); |
---|
1283 | option(prot); |
---|
1284 | ring r = 0,(a,b,c,d),dp; |
---|
1285 | ideal i = a+b+c+d,ab+ad+bc+cd,abc+abd+acd+bcd,abcd-1; |
---|
1286 | groebner(i); |
---|
1287 | |
---|
1288 | ring s = 0,(a,b,c,d),lp; |
---|
1289 | ideal i = imap(r,i); |
---|
1290 | groebner(i,"hilb"); |
---|
1291 | |
---|
1292 | ring R = (0,a),(b,c,d),lp; |
---|
1293 | minpoly = a2+1; |
---|
1294 | ideal i = a+b+c+d,ab+ad+bc+cd,abc+abd+acd+bcd,d2-c2b2; |
---|
1295 | groebner(i,"par2var","slimgb"); |
---|
1296 | |
---|
1297 | groebner(i,"fglm"); //computes a reduced standard basis |
---|
1298 | |
---|
1299 | option(set,opt); |
---|
1300 | } |
---|
1301 | |
---|
1302 | ////////////////////////////////////////////////////////////////////////// |
---|
1303 | |
---|
1304 | proc res(list #) |
---|
1305 | "@c we do texinfo here: |
---|
1306 | @cindex resolution, computation of |
---|
1307 | @table @code |
---|
1308 | @item @strong{Syntax:} |
---|
1309 | @code{res (} ideal_expression@code{,} int_expression @code{[,} any_expression @code{])} |
---|
1310 | @*@code{res (} module_expression@code{,} int_expression @code{[,} any_expression @code{])} |
---|
1311 | @item @strong{Type:} |
---|
1312 | resolution |
---|
1313 | @item @strong{Purpose:} |
---|
1314 | computes a (possibly minimal) free resolution of an ideal or module using |
---|
1315 | a heuristically chosen method. |
---|
1316 | @* The second (int) argument (say @code{k}) specifies the length of |
---|
1317 | the resolution. If it is not positive then @code{k} is assumed to be the |
---|
1318 | number of variables of the basering. |
---|
1319 | @* If a third argument is given, the returned resolution is minimized. |
---|
1320 | |
---|
1321 | Depending on the input, the returned resolution is computed using the |
---|
1322 | following methods: |
---|
1323 | @table @asis |
---|
1324 | @item @strong{quotient rings:} |
---|
1325 | @code{nres} (classical method using syzygies) , see @ref{nres}. |
---|
1326 | |
---|
1327 | @item @strong{homogeneous ideals and k=0:} |
---|
1328 | @code{lres} (La'Scala's method), see @ref{lres}. |
---|
1329 | |
---|
1330 | @item @strong{not minimized resolution and (homogeneous input with k not 0, or local rings):} |
---|
1331 | @code{sres} (Schreyer's method), see @ref{sres}. |
---|
1332 | |
---|
1333 | @item @strong{all other inputs:} |
---|
1334 | @code{mres} (classical method), see @ref{mres}. |
---|
1335 | @end table |
---|
1336 | @item @strong{Note:} |
---|
1337 | Accessing single elements of a resolution may require some partial |
---|
1338 | computations to be finished and may therefore take some time. |
---|
1339 | @end table |
---|
1340 | @c ref |
---|
1341 | See also |
---|
1342 | @ref{betti}; |
---|
1343 | @ref{ideal}; |
---|
1344 | @ref{minres}; |
---|
1345 | @ref{module}; |
---|
1346 | @ref{mres}; |
---|
1347 | @ref{nres}; |
---|
1348 | @ref{lres}; |
---|
1349 | @ref{hres}; |
---|
1350 | @ref{sres}; |
---|
1351 | @ref{resolution}. |
---|
1352 | @c ref |
---|
1353 | " |
---|
1354 | { |
---|
1355 | def P=basering; |
---|
1356 | if (size(#) < 2) |
---|
1357 | { |
---|
1358 | ERROR("res: need at least two arguments: ideal/module, int"); |
---|
1359 | } |
---|
1360 | |
---|
1361 | def m=#[1]; //the ideal or module |
---|
1362 | int i=#[2]; //the length of the resolution |
---|
1363 | if (i< 0) { i=0;} |
---|
1364 | |
---|
1365 | string varstr_P = varstr(P); |
---|
1366 | |
---|
1367 | int p_opt; |
---|
1368 | string s_opt = option(); |
---|
1369 | // set p_opt, if option(prot) is set |
---|
1370 | if (find(s_opt, "prot")) |
---|
1371 | { |
---|
1372 | p_opt = 1; |
---|
1373 | } |
---|
1374 | |
---|
1375 | if( (size(ideal(basering)) > 0) || (size(ringlist(P)) > 4) ) |
---|
1376 | { |
---|
1377 | // the quick hack for qrings - seems to fit most needs |
---|
1378 | // (lres is not implemented for qrings, sres is not so efficient) |
---|
1379 | // || non-commutative, since only n/m-res are implemented for NC rings |
---|
1380 | if (p_opt) { "using nres";} |
---|
1381 | return(nres(m,i)); |
---|
1382 | } |
---|
1383 | |
---|
1384 | if(homog(m)==1) |
---|
1385 | { |
---|
1386 | resolution re; |
---|
1387 | if (((i==0) or (i>=nvars(basering))) && typeof(m) != "module") |
---|
1388 | { |
---|
1389 | //LaScala for the homogeneous case and i == 0 |
---|
1390 | if (p_opt) { "using lres";} |
---|
1391 | re=lres(m,i); |
---|
1392 | if(size(#)>2) |
---|
1393 | { |
---|
1394 | re=minres(re); |
---|
1395 | } |
---|
1396 | } |
---|
1397 | else |
---|
1398 | { |
---|
1399 | if(size(#)>2) |
---|
1400 | { |
---|
1401 | if (p_opt) { "using mres";} |
---|
1402 | re=mres(m,i); |
---|
1403 | } |
---|
1404 | else |
---|
1405 | { |
---|
1406 | if (p_opt) { "using sres";} |
---|
1407 | re=sres(std(m),i); |
---|
1408 | } |
---|
1409 | } |
---|
1410 | return(re); |
---|
1411 | } |
---|
1412 | |
---|
1413 | //mres for the global non homogeneous case |
---|
1414 | if(find(ordstr(P),"s")==0) |
---|
1415 | { |
---|
1416 | string ri= "ring Phelp =" |
---|
1417 | +string(char(P))+",("+varstr_P+"),(dp,C);"; |
---|
1418 | ri = ri + "minpoly = "+string(minpoly) + ";"; |
---|
1419 | execute(ri); |
---|
1420 | def m=imap(P,m); |
---|
1421 | if (p_opt) { "using mres in another ring";} |
---|
1422 | list re=mres(m,i); |
---|
1423 | setring P; |
---|
1424 | resolution result=imap(Phelp,re); |
---|
1425 | if (size(#) > 2) {result = minres(result);} |
---|
1426 | return(result); |
---|
1427 | } |
---|
1428 | |
---|
1429 | //sres for the local case and not minimal resolution |
---|
1430 | if(size(#)<=2) |
---|
1431 | { |
---|
1432 | string ri= "ring Phelp =" |
---|
1433 | +string(char(P))+",("+varstr_P+"),(ls,c);"; |
---|
1434 | ri = ri + "minpoly = "+string(minpoly) + ";"; |
---|
1435 | execute(ri); |
---|
1436 | def m=imap(P,m); |
---|
1437 | m=std(m); |
---|
1438 | if (p_opt) { "using sres in another ring";} |
---|
1439 | list re=sres(m,i); |
---|
1440 | setring P; |
---|
1441 | resolution result=imap(Phelp,re); |
---|
1442 | return(result); |
---|
1443 | } |
---|
1444 | |
---|
1445 | //mres for the local case and minimal resolution |
---|
1446 | string ri= "ring Phelp =" |
---|
1447 | +string(char(P))+",("+varstr_P+"),(ls,C);"; |
---|
1448 | ri = ri + "minpoly = "+string(minpoly) + ";"; |
---|
1449 | execute(ri); |
---|
1450 | def m=imap(P,m); |
---|
1451 | if (p_opt) { "using mres in another ring";} |
---|
1452 | list re=mres(m,i); |
---|
1453 | setring P; |
---|
1454 | resolution result=imap(Phelp,re); |
---|
1455 | result = minres(result); |
---|
1456 | return(result); |
---|
1457 | } |
---|
1458 | example |
---|
1459 | {"EXAMPLE:"; echo = 2; |
---|
1460 | ring r=0,(x,y,z),dp; |
---|
1461 | ideal i=xz,yz,x3-y3; |
---|
1462 | def l=res(i,0); // homogeneous ideal: uses lres |
---|
1463 | l; |
---|
1464 | print(betti(l), "betti"); // input to betti may be of type resolution |
---|
1465 | l[2]; // element access may take some time |
---|
1466 | i=i,x+1; |
---|
1467 | l=res(i,0); // inhomogeneous ideal: uses mres |
---|
1468 | l; |
---|
1469 | ring rs=0,(x,y,z),ds; |
---|
1470 | ideal i=imap(r,i); |
---|
1471 | def l=res(i,0); // local ring not minimized: uses sres |
---|
1472 | l; |
---|
1473 | res(i,0,0); // local ring and minimized: uses mres |
---|
1474 | } |
---|
1475 | ///////////////////////////////////////////////////////////////////////// |
---|
1476 | |
---|
1477 | proc quot (m1,m2,list #) |
---|
1478 | "SYNTAX: @code{quot (} module_expression@code{,} module_expression @code{)} |
---|
1479 | @*@code{quot (} module_expression@code{,} module_expression@code{,} |
---|
1480 | int_expression @code{)} |
---|
1481 | @*@code{quot (} ideal_expression@code{,} ideal_expression @code{)} |
---|
1482 | @*@code{quot (} ideal_expression@code{,} ideal_expression@code{,} |
---|
1483 | int_expression @code{)} |
---|
1484 | TYPE: ideal |
---|
1485 | SYNTAX: @code{quot (} module_expression@code{,} ideal_expression @code{)} |
---|
1486 | TYPE: module |
---|
1487 | PURPOSE: computes the quotient of the 1st and the 2nd argument. |
---|
1488 | If a 3rd argument @code{n} is given the @code{n}-th method is used |
---|
1489 | (@code{n}=1...5). |
---|
1490 | SEE ALSO: quotient |
---|
1491 | EXAMPLE: example quot; shows an example" |
---|
1492 | { |
---|
1493 | if (((typeof(m1)!="ideal") and (typeof(m1)!="module")) |
---|
1494 | or ((typeof(m2)!="ideal") and (typeof(m2)!="module"))) |
---|
1495 | { |
---|
1496 | "USAGE: quot(m1, m2[, n]); m1, m2 two submodules of k^s,"; |
---|
1497 | " n (optional) integer (1<= n <=5)"; |
---|
1498 | "RETURN: the quotient of m1 and m2"; |
---|
1499 | "EXAMPLE: example quot; shows an example"; |
---|
1500 | return(); |
---|
1501 | } |
---|
1502 | if (typeof(m1)!=typeof(m2)) |
---|
1503 | { |
---|
1504 | return(quotient(m1,m2)); |
---|
1505 | } |
---|
1506 | if (size(#)>0) |
---|
1507 | { |
---|
1508 | if (typeof(#[1])=="int" ) |
---|
1509 | { |
---|
1510 | return(quot1(m1,m2,#[1])); |
---|
1511 | } |
---|
1512 | } |
---|
1513 | else |
---|
1514 | { |
---|
1515 | return(quot1(m1,m2,2)); |
---|
1516 | } |
---|
1517 | } |
---|
1518 | example |
---|
1519 | { "EXAMPLE:"; echo = 2; |
---|
1520 | ring r=181,(x,y,z),(c,ls); |
---|
1521 | ideal id1=maxideal(4); |
---|
1522 | ideal id2=x2+xyz,y2-z3y,z3+y5xz; |
---|
1523 | option(prot); |
---|
1524 | ideal id3=quotient(id1,id2); |
---|
1525 | id3; |
---|
1526 | ideal id4=quot(id1,id2,1); |
---|
1527 | id4; |
---|
1528 | ideal id5=quot(id1,id2,2); |
---|
1529 | id5; |
---|
1530 | } |
---|
1531 | |
---|
1532 | static proc quot1 (module m1, module m2,int n) |
---|
1533 | "USAGE: quot1(m1, m2, n); m1, m2 two submodules of k^s, |
---|
1534 | n integer (1<= n <=5) |
---|
1535 | RETURN: the quotient of m1 and m2 |
---|
1536 | EXAMPLE: example quot1; shows an example" |
---|
1537 | { |
---|
1538 | if (n==1) |
---|
1539 | { |
---|
1540 | return(quotient1(m1,m2)); |
---|
1541 | } |
---|
1542 | else |
---|
1543 | { |
---|
1544 | if (n==2) |
---|
1545 | { |
---|
1546 | return(quotient2(m1,m2)); |
---|
1547 | } |
---|
1548 | else |
---|
1549 | { |
---|
1550 | if (n==3) |
---|
1551 | { |
---|
1552 | return(quotient3(m1,m2)); |
---|
1553 | } |
---|
1554 | else |
---|
1555 | { |
---|
1556 | if (n==4) |
---|
1557 | { |
---|
1558 | return(quotient4(m1,m2)); |
---|
1559 | } |
---|
1560 | else |
---|
1561 | { |
---|
1562 | if (n==5) |
---|
1563 | { |
---|
1564 | return(quotient5(m1,m2)); |
---|
1565 | } |
---|
1566 | else |
---|
1567 | { |
---|
1568 | return(quotient(m1,m2)); |
---|
1569 | } |
---|
1570 | } |
---|
1571 | } |
---|
1572 | } |
---|
1573 | } |
---|
1574 | } |
---|
1575 | example |
---|
1576 | { "EXAMPLE:"; echo = 2; |
---|
1577 | ring r=181,(x,y,z),(c,ls); |
---|
1578 | ideal id1=maxideal(4); |
---|
1579 | ideal id2=x2+xyz,y2-z3y,z3+y5xz; |
---|
1580 | option(prot); |
---|
1581 | ideal id6=quotient(id1,id2); |
---|
1582 | id6; |
---|
1583 | ideal id7=quot1(id1,id2,1); |
---|
1584 | id7; |
---|
1585 | ideal id8=quot1(id1,id2,2); |
---|
1586 | id8; |
---|
1587 | } |
---|
1588 | |
---|
1589 | static proc quotient0(module a,module b) |
---|
1590 | { |
---|
1591 | module mm=b+a; |
---|
1592 | resolution rs=lres(mm,0); |
---|
1593 | list I=list(rs); |
---|
1594 | matrix M=I[2]; |
---|
1595 | matrix A[1][nrows(M)]=M[1..nrows(M),1]; |
---|
1596 | ideal i=A; |
---|
1597 | return (i); |
---|
1598 | } |
---|
1599 | proc quotient1(module a,module b) //17sec |
---|
1600 | "USAGE: quotient1(m1, m2); m1, m2 two submodules of k^s, |
---|
1601 | RETURN: the quotient of m1 and m2" |
---|
1602 | { |
---|
1603 | int i; |
---|
1604 | a=std(a); |
---|
1605 | module dummy; |
---|
1606 | module B=NF(b,a)+dummy; |
---|
1607 | ideal re=quotient(a,module(B[1])); |
---|
1608 | for(i=2;i<=ncols(B);i++) |
---|
1609 | { |
---|
1610 | re=intersect1(re,quotient(a,module(B[i]))); |
---|
1611 | } |
---|
1612 | return(re); |
---|
1613 | } |
---|
1614 | proc quotient2(module a,module b) //13sec |
---|
1615 | "USAGE: quotient2(m1, m2); m1, m2 two submodules of k^s, |
---|
1616 | RETURN: the quotient of m1 and m2" |
---|
1617 | { |
---|
1618 | a=std(a); |
---|
1619 | module dummy; |
---|
1620 | module bb=NF(b,a)+dummy; |
---|
1621 | int i=ncols(bb); |
---|
1622 | ideal re=quotient(a,module(bb[i])); |
---|
1623 | bb[i]=0; |
---|
1624 | module temp; |
---|
1625 | module temp1; |
---|
1626 | module bbb; |
---|
1627 | int mx; |
---|
1628 | i=i-1; |
---|
1629 | while (1) |
---|
1630 | { |
---|
1631 | if (i==0) break; |
---|
1632 | temp = a+bb*re; |
---|
1633 | temp1 = lead(interred(temp)); |
---|
1634 | mx=ncols(a); |
---|
1635 | if (ncols(temp1)>ncols(a)) |
---|
1636 | { |
---|
1637 | mx=ncols(temp1); |
---|
1638 | } |
---|
1639 | temp1 = matrix(temp1,1,mx)-matrix(lead(a),1,mx); |
---|
1640 | temp1 = dummy+temp1; |
---|
1641 | if (deg(temp1[1])<0) break; |
---|
1642 | re=intersect1(re,quotient(a,module(bb[i]))); |
---|
1643 | bb[i]=0; |
---|
1644 | i = i-1; |
---|
1645 | } |
---|
1646 | return(re); |
---|
1647 | } |
---|
1648 | proc quotient3(module a,module b) //89sec |
---|
1649 | "USAGE: quotient3(m1, m2); m1, m2 two submodules of k^s, |
---|
1650 | only for global rings |
---|
1651 | RETURN: the quotient of m1 and m2" |
---|
1652 | { |
---|
1653 | string s="ring @newr=("+charstr(basering)+ |
---|
1654 | "),("+varstr(basering)+",@t,@w),dp;"; |
---|
1655 | def @newP=basering; |
---|
1656 | execute(s); |
---|
1657 | module b=imap(@newP,b); |
---|
1658 | module a=imap(@newP,a); |
---|
1659 | int i; |
---|
1660 | int j=ncols(b); |
---|
1661 | vector @b; |
---|
1662 | for(i=1;i<=j;i++) |
---|
1663 | { |
---|
1664 | @b=@b+@t^(i-1)*@w^(j-i+1)*b[i]; |
---|
1665 | } |
---|
1666 | ideal re=quotient(a,module(@b)); |
---|
1667 | setring @newP; |
---|
1668 | ideal re=imap(@newr,re); |
---|
1669 | return(re); |
---|
1670 | } |
---|
1671 | proc quotient5(module a,module b) //89sec |
---|
1672 | "USAGE: quotient5(m1, m2); m1, m2 two submodules of k^s, |
---|
1673 | only for global rings |
---|
1674 | RETURN: the quotient of m1 and m2" |
---|
1675 | { |
---|
1676 | string s="ring @newr=("+charstr(basering)+ |
---|
1677 | "),("+varstr(basering)+",@t),dp;"; |
---|
1678 | def @newP=basering; |
---|
1679 | execute(s); |
---|
1680 | module b=imap(@newP,b); |
---|
1681 | module a=imap(@newP,a); |
---|
1682 | int i; |
---|
1683 | int j=ncols(b); |
---|
1684 | vector @b; |
---|
1685 | for(i=1;i<=j;i++) |
---|
1686 | { |
---|
1687 | @b=@b+@t^(i-1)*b[i]; |
---|
1688 | } |
---|
1689 | @b=homog(@b,@w); |
---|
1690 | ideal re=quotient(a,module(@b)); |
---|
1691 | setring @newP; |
---|
1692 | ideal re=imap(@newr,re); |
---|
1693 | return(re); |
---|
1694 | } |
---|
1695 | proc quotient4(module a,module b) //95sec |
---|
1696 | "USAGE: quotient4(m1, m2); m1, m2 two submodules of k^s, |
---|
1697 | only for global rings |
---|
1698 | RETURN: the quotient of m1 and m2" |
---|
1699 | { |
---|
1700 | string s="ring @newr=("+charstr(basering)+ |
---|
1701 | "),("+varstr(basering)+",@t),dp;"; |
---|
1702 | def @newP=basering; |
---|
1703 | execute(s); |
---|
1704 | module b=imap(@newP,b); |
---|
1705 | module a=imap(@newP,a); |
---|
1706 | int i; |
---|
1707 | vector @b=b[1]; |
---|
1708 | for(i=2;i<=ncols(b);i++) |
---|
1709 | { |
---|
1710 | @b=@b+@t^(i-1)*b[i]; |
---|
1711 | } |
---|
1712 | matrix sy=modulo(@b,a); |
---|
1713 | ideal re=sy; |
---|
1714 | setring @newP; |
---|
1715 | ideal re=imap(@newr,re); |
---|
1716 | return(re); |
---|
1717 | } |
---|
1718 | static proc intersect1(ideal i,ideal j) |
---|
1719 | { |
---|
1720 | def R=basering; |
---|
1721 | execute("ring gnir = ("+charstr(basering)+"), |
---|
1722 | ("+varstr(basering)+",@t),(C,dp);"); |
---|
1723 | ideal i=var(nvars(basering))*imap(R,i)+(var(nvars(basering))-1)*imap(R,j); |
---|
1724 | ideal j=eliminate(i,var(nvars(basering))); |
---|
1725 | setring R; |
---|
1726 | map phi=gnir,maxideal(1); |
---|
1727 | return(phi(j)); |
---|
1728 | } |
---|
1729 | |
---|
1730 | ////////////////////////////////////////////////////////////////// |
---|
1731 | /// |
---|
1732 | /// sprintf, fprintf printf |
---|
1733 | /// |
---|
1734 | proc sprintf(string fmt, list #) |
---|
1735 | "SYNTAX: @code{sprintf (} string_expression @code{[,} any_expressions |
---|
1736 | @code{] )} |
---|
1737 | RETURN: string |
---|
1738 | PURPOSE: @code{sprintf(fmt,...);} performs output formatting. The first |
---|
1739 | argument is a format control string. Additional arguments may be |
---|
1740 | required, depending on the content of the control string. A series |
---|
1741 | of output characters is generated as directed by the control string; |
---|
1742 | these characters are returned as a string. @* |
---|
1743 | The control string @code{fmt} is simply text to be copied, |
---|
1744 | except that the string may contain conversion specifications.@* |
---|
1745 | Type @code{help print;} for a listing of valid conversion |
---|
1746 | specifications. As an addition to the conversions of @code{print}, |
---|
1747 | the @code{%n} and @code{%2} conversion specification does not |
---|
1748 | consume an additional argument, but simply generates a newline |
---|
1749 | character. |
---|
1750 | NOTE: If one of the additional arguments is a list, then it should be |
---|
1751 | wrapped in an additional @code{list()} command, since passing a list |
---|
1752 | as an argument flattens the list by one level. |
---|
1753 | SEE ALSO: fprintf, printf, print, string |
---|
1754 | EXAMPLE : example sprintf; shows an example |
---|
1755 | " |
---|
1756 | { |
---|
1757 | int sfmt = size(fmt); |
---|
1758 | if (sfmt <= 1) |
---|
1759 | { |
---|
1760 | return (fmt); |
---|
1761 | } |
---|
1762 | int next, l, nnext; |
---|
1763 | string ret; |
---|
1764 | list formats = "%l", "%s", "%2l", "%2s", "%t", "%;", "%p", "%b", "%n", "%2"; |
---|
1765 | while (1) |
---|
1766 | { |
---|
1767 | if (size(#) <= 0) |
---|
1768 | { |
---|
1769 | return (ret + fmt); |
---|
1770 | } |
---|
1771 | nnext = 0; |
---|
1772 | while (nnext < sfmt) |
---|
1773 | { |
---|
1774 | nnext = find(fmt, "%", nnext + 1); |
---|
1775 | if (nnext == 0) |
---|
1776 | { |
---|
1777 | next = 0; |
---|
1778 | break; |
---|
1779 | } |
---|
1780 | l = 1; |
---|
1781 | while (l <= size(formats)) |
---|
1782 | { |
---|
1783 | next = find(fmt, formats[l], nnext); |
---|
1784 | if (next == nnext) break; |
---|
1785 | l++; |
---|
1786 | } |
---|
1787 | if (next == nnext) break; |
---|
1788 | } |
---|
1789 | if (next == 0) |
---|
1790 | { |
---|
1791 | return (ret + fmt); |
---|
1792 | } |
---|
1793 | if (formats[l] != "%2" && formats[l] != "%n") |
---|
1794 | { |
---|
1795 | ret = ret + fmt[1, next - 1] + print(#[1], formats[l]); |
---|
1796 | # = delete(#, 1); |
---|
1797 | } |
---|
1798 | else |
---|
1799 | { |
---|
1800 | ret = ret + fmt[1, next - 1] + print("", "%2s"); |
---|
1801 | } |
---|
1802 | if (size(fmt) <= (next + size(formats[l]) - 1)) |
---|
1803 | { |
---|
1804 | return (ret); |
---|
1805 | } |
---|
1806 | fmt = fmt[next + size(formats[l]), size(fmt)-next-size(formats[l]) + 1]; |
---|
1807 | } |
---|
1808 | } |
---|
1809 | example |
---|
1810 | { "EXAMPLE:"; echo=2; |
---|
1811 | ring r=0,(x,y,z),dp; |
---|
1812 | module m=[1,y],[0,x+z]; |
---|
1813 | intmat M=betti(mres(m,0)); |
---|
1814 | list l = r, m, M; |
---|
1815 | string s = sprintf("s:%s,%n l:%l", 1, 2); s; |
---|
1816 | s = sprintf("s:%n%s", l); s; |
---|
1817 | s = sprintf("s:%2%s", list(l)); s; |
---|
1818 | s = sprintf("2l:%n%2l", list(l)); s; |
---|
1819 | s = sprintf("%p", list(l)); s; |
---|
1820 | s = sprintf("%;", list(l)); s; |
---|
1821 | s = sprintf("%b", M); s; |
---|
1822 | } |
---|
1823 | |
---|
1824 | proc printf(string fmt, list #) |
---|
1825 | "SYNTAX: @code{printf (} string_expression @code{[,} any_expressions@code{] )} |
---|
1826 | RETURN: none |
---|
1827 | PURPOSE: @code{printf(fmt,...);} performs output formatting. The first |
---|
1828 | argument is a format control string. Additional arguments may be |
---|
1829 | required, depending on the content of the control string. A series |
---|
1830 | of output characters is generated as directed by the control string; |
---|
1831 | these characters are displayed (i.e., printed to standard out). @* |
---|
1832 | The control string @code{fmt} is simply text to be copied, except |
---|
1833 | that the string may contain conversion specifications. @* |
---|
1834 | Type @code{help print;} for a listing of valid conversion |
---|
1835 | specifications. As an addition to the conversions of @code{print}, |
---|
1836 | the @code{%n} and @code{%2} conversion specification does not |
---|
1837 | consume an additional argument, but simply generates a newline |
---|
1838 | character. |
---|
1839 | NOTE: If one of the additional arguments is a list, then it should be |
---|
1840 | enclosed once more into a @code{list()} command, since passing a |
---|
1841 | list as an argument flattens the list by one level. |
---|
1842 | SEE ALSO: sprintf, fprintf, print, string |
---|
1843 | EXAMPLE : example printf; shows an example |
---|
1844 | " |
---|
1845 | { |
---|
1846 | write("", sprintf(fmt, #)); |
---|
1847 | } |
---|
1848 | example |
---|
1849 | { "EXAMPLE:"; echo=2; |
---|
1850 | ring r=0,(x,y,z),dp; |
---|
1851 | module m=[1,y],[0,x+z]; |
---|
1852 | intmat M=betti(mres(m,0)); |
---|
1853 | list l=r,m,matrix(M); |
---|
1854 | printf("s:%s,l:%l",1,2); |
---|
1855 | printf("s:%s",l); |
---|
1856 | printf("s:%s",list(l)); |
---|
1857 | printf("2l:%2l",list(l)); |
---|
1858 | printf("%p",matrix(M)); |
---|
1859 | printf("%;",matrix(M)); |
---|
1860 | printf("%b",M); |
---|
1861 | } |
---|
1862 | |
---|
1863 | |
---|
1864 | proc fprintf(link l, string fmt, list #) |
---|
1865 | "SYNTAX: @code{fprintf (} link_expression@code{,} string_expression @code{[,} |
---|
1866 | any_expressions@code{] )} |
---|
1867 | RETURN: none |
---|
1868 | PURPOSE: @code{fprintf(l,fmt,...);} performs output formatting. |
---|
1869 | The second argument is a format control string. Additional |
---|
1870 | arguments may be required, depending on the content of the |
---|
1871 | control string. A series of output characters is generated as |
---|
1872 | directed by the control string; these characters are |
---|
1873 | written to the link l. |
---|
1874 | The control string @code{fmt} is simply text to be copied, except |
---|
1875 | that the string may contain conversion specifications.@* |
---|
1876 | Type @code{help print;} for a listing of valid conversion |
---|
1877 | specifications. As an addition to the conversions of @code{print}, |
---|
1878 | the @code{%n} and @code{%2} conversion specification does not |
---|
1879 | consume an additional argument, but simply generates a newline |
---|
1880 | character. |
---|
1881 | NOTE: If one of the additional arguments is a list, then it should be |
---|
1882 | enclosed once more into a @code{list()} command, since passing |
---|
1883 | a list as an argument flattens the list by one level. |
---|
1884 | SEE ALSO: sprintf, printf, print, string |
---|
1885 | EXAMPLE : example fprintf; shows an example |
---|
1886 | " |
---|
1887 | { |
---|
1888 | write(l, sprintf(fmt, #)); |
---|
1889 | } |
---|
1890 | example |
---|
1891 | { "EXAMPLE:"; echo=2; |
---|
1892 | ring r=0,(x,y,z),dp; |
---|
1893 | module m=[1,y],[0,x+z]; |
---|
1894 | intmat M=betti(mres(m,0)); |
---|
1895 | list l=r,m,M; |
---|
1896 | link li=""; // link to stdout |
---|
1897 | fprintf(li,"s:%s,l:%l",1,2); |
---|
1898 | fprintf(li,"s:%s",l); |
---|
1899 | fprintf(li,"s:%s",list(l)); |
---|
1900 | fprintf(li,"2l:%2l",list(l)); |
---|
1901 | fprintf(li,"%p",list(l)); |
---|
1902 | fprintf(li,"%;",list(l)); |
---|
1903 | fprintf(li,"%b",M); |
---|
1904 | } |
---|
1905 | |
---|
1906 | ////////////////////////////////////////////////////////////////////////// |
---|
1907 | |
---|
1908 | /* |
---|
1909 | proc minres(list #) |
---|
1910 | { |
---|
1911 | if (size(#) == 2) |
---|
1912 | { |
---|
1913 | if (typeof(#[1]) == "ideal" || typeof(#[1]) == "module") |
---|
1914 | { |
---|
1915 | if (typeof(#[2] == "int")) |
---|
1916 | { |
---|
1917 | return (res(#[1],#[2],1)); |
---|
1918 | } |
---|
1919 | } |
---|
1920 | } |
---|
1921 | |
---|
1922 | if (typeof(#[1]) == "resolution") |
---|
1923 | { |
---|
1924 | return minimizeres(#[1]); |
---|
1925 | } |
---|
1926 | else |
---|
1927 | { |
---|
1928 | return minimizeres(#); |
---|
1929 | } |
---|
1930 | |
---|
1931 | } |
---|
1932 | */ |
---|
1933 | /////////////////////////////////////////////////////////////////////////////// |
---|
1934 | |
---|
1935 | proc weightKB(def stc, int dd, list wim) |
---|
1936 | "SYNTAX: @code{weightKB (} module_expression@code{,} int_expression @code{,} |
---|
1937 | list_expression @code{)}@* |
---|
1938 | @code{weightKB (} ideal_expression@code{,} int_expression@code{,} |
---|
1939 | list_expression @code{)} |
---|
1940 | RETURN: the same as the input type of the first argument |
---|
1941 | PURPOSE: If @code{I,d,wim} denotes the three arguments then weightKB |
---|
1942 | computes the weighted degree- @code{d} part of a vector space basis |
---|
1943 | (consisting of monomials) of the quotient ring, resp. of the |
---|
1944 | quotient module, modulo @code{I} w.r.t. weights given by @code{wim} |
---|
1945 | The information about the weights is given as a list of two intvec: |
---|
1946 | @code{wim[1]} weights for all variables (positive), |
---|
1947 | @code{wim[2]} weights for the module generators. |
---|
1948 | NOTE: This is a generalization of the command @code{kbase} with the same |
---|
1949 | first two arguments. |
---|
1950 | SEE ALSO: kbase |
---|
1951 | EXAMPLE: example weightKB; shows an example |
---|
1952 | " |
---|
1953 | { |
---|
1954 | if(checkww(wim)){ERROR("wrong weights";);} |
---|
1955 | kbclass(); |
---|
1956 | wwtop=wim[1]; |
---|
1957 | stc=interred(lead(stc)); |
---|
1958 | if(typeof(stc)=="ideal") |
---|
1959 | { |
---|
1960 | stdtop=stc; |
---|
1961 | ideal out=widkbase(dd); |
---|
1962 | delkbclass(); |
---|
1963 | out=simplify(out,2); // delete 0 |
---|
1964 | return(out); |
---|
1965 | } |
---|
1966 | list mbase=kbprepare(stc); |
---|
1967 | module mout; |
---|
1968 | int im,ii; |
---|
1969 | if(size(wim)>1){mmtop=wim[2];} |
---|
1970 | else{mmtop=0;} |
---|
1971 | for(im=size(mbase);im>0;im--) |
---|
1972 | { |
---|
1973 | stdtop=mbase[im]; |
---|
1974 | if(im>size(mmtop)){ii=dd;} |
---|
1975 | else{ii=dd-mmtop[im];} |
---|
1976 | mout=mout+widkbase(ii)*gen(im); |
---|
1977 | } |
---|
1978 | delkbclass(); |
---|
1979 | mout=simplify(mout,2); // delete 0 |
---|
1980 | return(mout); |
---|
1981 | } |
---|
1982 | example |
---|
1983 | { "EXAMPLE:"; echo=2; |
---|
1984 | ring R=0, (x,y), wp(1,2); |
---|
1985 | weightKB(ideal(0),3,intvec(1,2)); |
---|
1986 | } |
---|
1987 | |
---|
1988 | /////////////////////////////////////////////////////////////////////////////// |
---|
1989 | |
---|
1990 | proc datetime() |
---|
1991 | "SYNTAX: @code{datetime ()} |
---|
1992 | RETURN: string |
---|
1993 | PURPOSE: return the curent date and time as a string |
---|
1994 | EXAMPLE: example datetime; shows an example |
---|
1995 | " |
---|
1996 | { |
---|
1997 | return(read("|: date")); |
---|
1998 | } |
---|
1999 | example |
---|
2000 | { "EXAMPLE:"; echo=2; |
---|
2001 | datetime(); |
---|
2002 | } |
---|
2003 | |
---|
2004 | /////////////////////////////////////////////////////////////////////////////// |
---|
2005 | // construct global values |
---|
2006 | static proc kbclass() |
---|
2007 | { |
---|
2008 | intvec wwtop,mmtop; |
---|
2009 | export (wwtop,mmtop); |
---|
2010 | ideal stdtop,kbtop; |
---|
2011 | export (stdtop,kbtop); |
---|
2012 | } |
---|
2013 | // delete global values |
---|
2014 | static proc delkbclass() |
---|
2015 | { |
---|
2016 | kill wwtop,mmtop; |
---|
2017 | kill stdtop,kbtop; |
---|
2018 | } |
---|
2019 | // select parts of the modul |
---|
2020 | static proc kbprepare(module mstc) |
---|
2021 | { |
---|
2022 | list rr; |
---|
2023 | ideal kk; |
---|
2024 | int i1,i2; |
---|
2025 | mstc=transpose(mstc); |
---|
2026 | for(i1=ncols(mstc);i1>0;i1--) |
---|
2027 | { |
---|
2028 | kk=0; |
---|
2029 | for(i2=nrows(mstc[i1]);i2>0;i2--) |
---|
2030 | { |
---|
2031 | kk=kk+mstc[i1][i2]; |
---|
2032 | } |
---|
2033 | rr[i1]=kk; |
---|
2034 | } |
---|
2035 | return(rr); |
---|
2036 | } |
---|
2037 | // check for weights |
---|
2038 | static proc checkww(list vv) |
---|
2039 | { |
---|
2040 | if(typeof(vv[1])!="intvec"){return(1);} |
---|
2041 | intvec ww=vv[1]; |
---|
2042 | int mv=nvars(basering); |
---|
2043 | if(size(ww)<mv){return(1);} |
---|
2044 | while(mv>0) |
---|
2045 | { |
---|
2046 | if(ww[mv]<=0){return(1);} |
---|
2047 | mv--; |
---|
2048 | } |
---|
2049 | if(size(vv)>1) |
---|
2050 | { |
---|
2051 | if(typeof(vv[2])!="intvec"){return(1);} |
---|
2052 | } |
---|
2053 | return(0); |
---|
2054 | } |
---|
2055 | /////////////////////////////////////////////////////// |
---|
2056 | // The "Caller" for ideals |
---|
2057 | // dd - the degree of the result |
---|
2058 | static proc widkbase(int dd) |
---|
2059 | { |
---|
2060 | if((size(stdtop)==1)&&(deg(stdtop[1])==0)){return(0);} |
---|
2061 | if(dd<=0) |
---|
2062 | { |
---|
2063 | if(dd<0){return(0);} |
---|
2064 | else{return(1);} |
---|
2065 | } |
---|
2066 | int m1,m2; |
---|
2067 | m1=nvars(basering); |
---|
2068 | while(wwtop[m1]>dd) |
---|
2069 | { |
---|
2070 | m1--; |
---|
2071 | if(m1==0){return(0);} |
---|
2072 | } |
---|
2073 | attrib(stdtop,"isSB",1); |
---|
2074 | poly mo=1; |
---|
2075 | if(m1==1) |
---|
2076 | { |
---|
2077 | m2=dd/wwtop[1]; |
---|
2078 | if((m2*wwtop[1])==dd) |
---|
2079 | { |
---|
2080 | mo=var(1)^m2; |
---|
2081 | if(reduce(mo,stdtop)==mo){return(mo);} |
---|
2082 | else{return(0);} |
---|
2083 | } |
---|
2084 | } |
---|
2085 | kbtop=0; |
---|
2086 | m2=dd; |
---|
2087 | weightmon(m1-1,m2,mo); |
---|
2088 | while(m2>=wwtop[m1]) |
---|
2089 | { |
---|
2090 | m2=m2-wwtop[m1]; |
---|
2091 | mo=var(m1)*mo; |
---|
2092 | if(m2==0) |
---|
2093 | { |
---|
2094 | if((mo!=0) and (reduce(mo,stdtop)==mo)) |
---|
2095 | { |
---|
2096 | kbtop[ncols(kbtop)+1]=mo; |
---|
2097 | return(kbtop); |
---|
2098 | } |
---|
2099 | } |
---|
2100 | weightmon(m1-1,m2,mo); |
---|
2101 | } |
---|
2102 | return(kbtop); |
---|
2103 | } |
---|
2104 | ///////////////////////////////////////////////////////// |
---|
2105 | // the recursive procedure |
---|
2106 | // va - number of the variable |
---|
2107 | // drest - rest of the degree |
---|
2108 | // mm - the candidate |
---|
2109 | static proc weightmon(int va, int drest, poly mm) |
---|
2110 | { |
---|
2111 | while(wwtop[va]>drest) |
---|
2112 | { |
---|
2113 | va--; |
---|
2114 | if(va==0){return();} |
---|
2115 | } |
---|
2116 | int m2; |
---|
2117 | if(va==1) |
---|
2118 | { |
---|
2119 | m2=drest/wwtop[1]; |
---|
2120 | if((m2*wwtop[1])==drest) |
---|
2121 | { |
---|
2122 | mm=var(1)^m2*mm; |
---|
2123 | if ((mm!=0) and (reduce(mm,stdtop)==mm)) |
---|
2124 | { |
---|
2125 | kbtop[ncols(kbtop)+1]=mm; |
---|
2126 | } |
---|
2127 | } |
---|
2128 | return(); |
---|
2129 | } |
---|
2130 | m2=drest; |
---|
2131 | if ((mm!=0) and (reduce(mm,stdtop)==mm)) |
---|
2132 | { |
---|
2133 | weightmon(va-1,m2,mm); |
---|
2134 | } |
---|
2135 | while(m2>=wwtop[va]) |
---|
2136 | { |
---|
2137 | m2=m2-wwtop[va]; |
---|
2138 | mm=var(va)*mm; |
---|
2139 | if(m2==0) |
---|
2140 | { |
---|
2141 | if ((mm!=0) and (reduce(mm,stdtop)==mm)) |
---|
2142 | { |
---|
2143 | kbtop[ncols(kbtop)+1]=mm; |
---|
2144 | return(); |
---|
2145 | } |
---|
2146 | } |
---|
2147 | if ((mm!=0) and (reduce(mm,stdtop)==mm)) |
---|
2148 | { |
---|
2149 | weightmon(va-1,m2,mm); |
---|
2150 | } |
---|
2151 | } |
---|
2152 | return(); |
---|
2153 | } |
---|
2154 | example |
---|
2155 | { "EXAMPLE:"; echo=2; |
---|
2156 | ring r=0,(x,y,z),dp; |
---|
2157 | ideal i = x6,y4,xyz; |
---|
2158 | intvec w = 2,3,6; |
---|
2159 | weightKB(i, 12, list(w)); |
---|
2160 | } |
---|
2161 | |
---|
2162 | /////////////////////////////////////////////////////////////////////////////// |
---|
2163 | /* |
---|
2164 | Versuche: |
---|
2165 | /////////////////////////////////////////////////////////////////////////////// |
---|
2166 | proc downsizeSB (I, list #) |
---|
2167 | "USAGE: downsizeSB(I [,l]); I ideal, l list of integers [default: l=0] |
---|
2168 | RETURN: intvec, say v, with v[j] either 1 or 0. We have v[j]=1 if |
---|
2169 | leadmonom(I[j]) is divisible by some leadmonom(I[k]) or if |
---|
2170 | leadmonom(i[j]) == leadmonom(i[k]) and l[j] >= l[k], with k!=j. |
---|
2171 | PURPOSE: The procedure is applied in a situation where the standard basis |
---|
2172 | computation in the basering R is done via a conversion through an |
---|
2173 | overring Phelp with additional variables and where a direct |
---|
2174 | imap from Phelp to R is too expensive. |
---|
2175 | Assume Phelp is created by the procedure @code{par2varRing} or |
---|
2176 | @code{hilbRing} and IPhelp is a SB in Phelp [ with l[j]= |
---|
2177 | length(IPhelp(j)) or any other integer reflecting the complexity |
---|
2178 | of a IPhelp[j] ]. Let I = lead(IPhelp) mapped to R and compute |
---|
2179 | v = downsizeSB(imap(Phelp,I),l) in R. Then, if Ihelp[j] is deleted |
---|
2180 | for all j with v[j]=1, we can apply imap to the remaining generators |
---|
2181 | of Ihelp and still get SB in R (in general not minimal). |
---|
2182 | EXAMPLE: example downsizeSB; shows an example" |
---|
2183 | { |
---|
2184 | int k,j; |
---|
2185 | intvec v,l; |
---|
2186 | poly M,N,W; |
---|
2187 | int c=size(I); |
---|
2188 | if( size(#) != 0 ) |
---|
2189 | { |
---|
2190 | if ( typeof(#[1]) == "intvec" ) |
---|
2191 | { |
---|
2192 | l = #[1]; |
---|
2193 | } |
---|
2194 | else |
---|
2195 | { |
---|
2196 | ERROR("// 2nd argument must be an intvec"); |
---|
2197 | } |
---|
2198 | } |
---|
2199 | |
---|
2200 | l[c+1]=0; |
---|
2201 | v[c]=0; |
---|
2202 | |
---|
2203 | j=0; |
---|
2204 | while(j<c-1) |
---|
2205 | { |
---|
2206 | j++; |
---|
2207 | M = leadmonom(I[j]); |
---|
2208 | if( M != 0 ) |
---|
2209 | { |
---|
2210 | for( k=j+1; k<=c; k++ ) |
---|
2211 | { |
---|
2212 | N = leadmonom(I[k]); |
---|
2213 | if( N != 0 ) |
---|
2214 | { |
---|
2215 | if( (M==N) && (l[j]>l[k]) ) |
---|
2216 | { |
---|
2217 | I[j]=0; |
---|
2218 | v[j]=1; |
---|
2219 | break; |
---|
2220 | } |
---|
2221 | if( (M==N) && (l[j]<=l[k]) || N/M != 0 ) |
---|
2222 | { |
---|
2223 | I[k]=0; |
---|
2224 | v[k]=1; |
---|
2225 | } |
---|
2226 | } |
---|
2227 | } |
---|
2228 | } |
---|
2229 | } |
---|
2230 | return(v); |
---|
2231 | } |
---|
2232 | example |
---|
2233 | { "EXAMPLE:"; echo = 2; |
---|
2234 | ring r = 0,(x,y,z,t),(dp(3),dp); |
---|
2235 | ideal i = x+y+z+t,xy+yz+xt+zt,xyz+xyt+xzt+yzt,xyzt-t4; |
---|
2236 | ideal Id = std(i); |
---|
2237 | ideal I = lead(Id); I; |
---|
2238 | ring S = (0,t),(x,y,z),dp; |
---|
2239 | downsizeSB(imap(r,I)); |
---|
2240 | //Id[5] can be deleted, we still have a SB of i in the ring S |
---|
2241 | |
---|
2242 | ring R = (0,x),(y,z,u),lp; |
---|
2243 | ideal i = x+y+z+u,xy+xu+yz+zu,xyz+xyu+xzu+yzu,xyzu-1; |
---|
2244 | def Phelp = par2varRing()[1]; |
---|
2245 | setring Phelp; |
---|
2246 | ideal IPhelp = std(imap(R,i)); |
---|
2247 | ideal I = lead(IPhelp); |
---|
2248 | setring R; |
---|
2249 | ideal I = imap(Phelp,I); I; |
---|
2250 | intvec v = downsizeSB(I); v; |
---|
2251 | } |
---|
2252 | /////////////////////////////////////////////////////////////////////////// |
---|
2253 | // PROBLEM: Die Prozedur funktioniert nur fuer Ringe die global bekannt |
---|
2254 | // sind, also interaktiv, aber nicht aus einer Prozedur. |
---|
2255 | // Z.B. funktioniert example imapDownsize; nicht |
---|
2256 | |
---|
2257 | proc imapDownsize (string R, string I) |
---|
2258 | "SYNTAX: @code{imapDownsize (} string @code{,} string @code{)} *@ |
---|
2259 | First string must be the string of the name of a ring, second |
---|
2260 | string must be the string of the name of an object in the ring. |
---|
2261 | TYPE: same type as the object with name the second string |
---|
2262 | PURPOSE: maps the object given by the second string to the basering. |
---|
2263 | If R resp. I are the first resp. second string, then |
---|
2264 | imapDownsize(R,I) is equivalent to simplify(imap(`R`,`I`),34). |
---|
2265 | NOTE: imapDownsize is usually faster than imap if `I` is large and if |
---|
2266 | simplify has a great effect, since the procedure maps only those |
---|
2267 | generators from `I` which are not killed by simplify( - ,34). |
---|
2268 | This is useful if `I` is a standard bases for a block ordering of |
---|
2269 | `R` and if some variables from the last block in `R` are mapped |
---|
2270 | to parameters. Then the returned result is a standard basis in |
---|
2271 | the basering. |
---|
2272 | SEE ALSO: imap, fetch, map |
---|
2273 | EXAMPLE: example imapDownsize; shows an example" |
---|
2274 | { |
---|
2275 | def BR = basering; |
---|
2276 | int k; |
---|
2277 | |
---|
2278 | setring `R`; |
---|
2279 | def @leadI@ = lead(`I`); |
---|
2280 | int s = ncols(@leadI@); |
---|
2281 | setring BR; |
---|
2282 | ideal @leadI@ = simplify(imap(`R`,@leadI@),32); |
---|
2283 | intvec vi; |
---|
2284 | for (k=1; k<=s; k++) |
---|
2285 | { |
---|
2286 | vi[k] = @leadI@[k]==0; |
---|
2287 | } |
---|
2288 | kill @leadI@; |
---|
2289 | |
---|
2290 | setring `R`; |
---|
2291 | kill @leadI@; |
---|
2292 | for (k=1; k<=s; k++) |
---|
2293 | { |
---|
2294 | if( vi[k]==1 ) |
---|
2295 | { |
---|
2296 | `I`[k]=0; |
---|
2297 | } |
---|
2298 | } |
---|
2299 | `I` = simplify(`I`,2); |
---|
2300 | |
---|
2301 | setring BR; |
---|
2302 | return(imap(`R`,`I`)); |
---|
2303 | } |
---|
2304 | example |
---|
2305 | { "EXAMPLE:"; echo = 2; |
---|
2306 | ring r = 0,(x,y,z,t),(dp(3),dp); |
---|
2307 | ideal i = x+y+z+t,xy+yz+xt+zt,xyz+xyt+xzt+yzt,xyzt-1; |
---|
2308 | i = std(i); i; |
---|
2309 | |
---|
2310 | ring s = (0,t),(x,y,z),dp; |
---|
2311 | imapDownsize("r","i"); //i[5] is omitted since lead(i[2]) | lead(i[5]) |
---|
2312 | } |
---|
2313 | /////////////////////////////////////////////////////////////////////////////// |
---|
2314 | //die folgende proc war fuer groebner mit fglm vorgesehen, ist aber zu teuer. |
---|
2315 | //Um die projektive Dimension korrekt zu berechnen, muss man aber teuer |
---|
2316 | //voerher ein SB bzgl. einer Gradordnung berechnen und dann homogenisieren. |
---|
2317 | //Sonst koennen hoeherdimensionale Komponenten in Unendlich entstehen |
---|
2318 | |
---|
2319 | proc projInvariants(ideal i,list #) |
---|
2320 | "SYNTAX: @code{projInvariants (} ideal_expression @code{)} @* |
---|
2321 | @code{projInvariants (} ideal_expression@code{,} list of string_expres sions@code{)} |
---|
2322 | TYPE: list, say L, with L[1] and L[2] of type int and L[3] of type intvec |
---|
2323 | PURPOSE: Computes the (projective) dimension (L[1]), degree (L[2]) and the |
---|
2324 | first Hilbert series (L[3], as intvec) of the homogenized ideal |
---|
2325 | in the ring given by the procedure @code{hilbRing} with global |
---|
2326 | ordering dp (resp. wp if the variables have weights >1) |
---|
2327 | If an argument of type string @code{\"std\"} resp. @code{\"slimgb\"} |
---|
2328 | is given, the standard basis computatuion uses @code{std} or |
---|
2329 | @code{slimgb}, otherwise a heuristically chosen method (default) |
---|
2330 | NOTE: Homogenized means weighted homogenized with respect to the weights |
---|
2331 | w[i] of the variables var(i) of the basering. The returned dimension, |
---|
2332 | degree and Hilbertseries are the respective invariants of the |
---|
2333 | projective variety defined by the homogenized ideal. The dimension |
---|
2334 | is equal to the (affine) dimension of the ideal in the basering |
---|
2335 | (degree and Hilbert series make only sense for homogeneous ideals). |
---|
2336 | SEE ALSO: dim, dmult, hilb |
---|
2337 | KEYWORDS: dimension, degree, Hilbert function |
---|
2338 | EXAMPLE: example projInvariants; shows an example" |
---|
2339 | { |
---|
2340 | def P = basering; |
---|
2341 | int p_opt; |
---|
2342 | string s_opt = option(); |
---|
2343 | if (find(option(), "prot")) { p_opt = 1; } |
---|
2344 | |
---|
2345 | //---------------- check method and clear denomintors -------------------- |
---|
2346 | int k; |
---|
2347 | string method; |
---|
2348 | for (k=1; k<=size(#); k++) |
---|
2349 | { |
---|
2350 | if (typeof(#[k]) == "string") |
---|
2351 | { |
---|
2352 | method = method + "," + #[k]; |
---|
2353 | } |
---|
2354 | } |
---|
2355 | |
---|
2356 | if (npars(P) > 0) //clear denominators of parameters |
---|
2357 | { |
---|
2358 | for( k=ncols(i); k>0; k-- ) |
---|
2359 | { |
---|
2360 | i[k]=cleardenom(i[k]); |
---|
2361 | } |
---|
2362 | } |
---|
2363 | |
---|
2364 | //------------------------ change to hilbRing ---------------------------- |
---|
2365 | list hiRi = hilbRing(i); |
---|
2366 | intvec W = hiRi[2]; |
---|
2367 | def Philb = hiRi[1]; //note: Philb is no qring and the predefined |
---|
2368 | setring Philb; //ideal Id(1) in Philb is homogeneous |
---|
2369 | int di, de; //for dimension, degree |
---|
2370 | intvec hi; //for hilbert series |
---|
2371 | |
---|
2372 | //-------- compute Hilbert function of homogenized ideal in Philb --------- |
---|
2373 | //Philb has only 1 block. There are three cases |
---|
2374 | |
---|
2375 | string algorithm; //possibilities: std, slimgb, stdorslimgb |
---|
2376 | //define algorithm: |
---|
2377 | if( find(method,"std") && !find(method,"slimgb") ) |
---|
2378 | { |
---|
2379 | algorithm = "std"; |
---|
2380 | } |
---|
2381 | if( find(method,"slimgb") && !find(method,"std") ) |
---|
2382 | { |
---|
2383 | algorithm = "slimgb"; |
---|
2384 | } |
---|
2385 | if( find(method,"std") && find(method,"slimgb") || |
---|
2386 | (!find(method,"std") && !find(method,"slimgb")) ) |
---|
2387 | { |
---|
2388 | algorithm = "stdorslimgb"; |
---|
2389 | } |
---|
2390 | |
---|
2391 | if ( algorithm=="std" || ( algorithm=="stdorslimgb" && char(P)>0 ) ) |
---|
2392 | { |
---|
2393 | if (p_opt) {"std in ring " + string(Philb);} |
---|
2394 | Id(1) = std(Id(1)); |
---|
2395 | di = dim(Id(1))-1; |
---|
2396 | de = mult(Id(1)); |
---|
2397 | hi = hilb( Id(1),1,W ); |
---|
2398 | } |
---|
2399 | if ( algorithm=="slimgb" || ( algorithm=="stdorslimgb" && char(P)==0 ) ) |
---|
2400 | { |
---|
2401 | if (p_opt) {"slimgb in ring " + string(Philb);} |
---|
2402 | Id(1) = slimgb(Id(1)); |
---|
2403 | di = dim( Id(1) ); |
---|
2404 | if (di > -1) |
---|
2405 | { |
---|
2406 | di = di-1; |
---|
2407 | } |
---|
2408 | de = mult( Id(1) ); |
---|
2409 | hi = hilb( Id(1),1,W ); |
---|
2410 | } |
---|
2411 | kill Philb; |
---|
2412 | list L = di,de,hi; |
---|
2413 | return(L); |
---|
2414 | } |
---|
2415 | example |
---|
2416 | { "EXAMPLE:"; echo = 2; |
---|
2417 | ring r = 32003,(x,y,z),lp; |
---|
2418 | ideal i = y2-xz,x2-z; |
---|
2419 | projInvariants(i); |
---|
2420 | |
---|
2421 | ring R = (0),(x,y,z,u,v),lp; |
---|
2422 | //minpoly = x2+1; |
---|
2423 | ideal i = x2+1,x2+y+z+u+v,xyzuv-1; |
---|
2424 | projInvariants(i); |
---|
2425 | qring S =std(x2+1); |
---|
2426 | ideal i = imap(R,i); |
---|
2427 | projInvariants(i); |
---|
2428 | } |
---|
2429 | |
---|
2430 | */ |
---|
2431 | /////////////////////////////////////////////////////////////////////////////// |
---|
2432 | // EXAMPLES |
---|
2433 | /////////////////////////////////////////////////////////////////////////////// |
---|
2434 | /* |
---|
2435 | example stdfglm; |
---|
2436 | example stdhilb; |
---|
2437 | example groebner; |
---|
2438 | example res; |
---|
2439 | example sprintf; |
---|
2440 | example fprintf; |
---|
2441 | example printf; |
---|
2442 | example weightKB; |
---|
2443 | example qslimgb; |
---|
2444 | example par2varRing; |
---|
2445 | */ |
---|
2446 | static proc mod_init() |
---|
2447 | { |
---|
2448 | //int pagelength=24; |
---|
2449 | //exportto(Top,pagelength); |
---|
2450 | } |
---|