1 | //////////////////////////////////////////////////////// |
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2 | version="version fpadim.lib 4.1.1.4 Oct_2018 "; // $Id$ |
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3 | category="Noncommutative"; |
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4 | info=" |
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5 | LIBRARY: fpadim.lib Vector space dimension, basis and Hilbert series for finitely presented algebras (Letterplace) |
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6 | AUTHORS: Grischa Studzinski, grischa.studzinski at rwth-aachen.de |
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7 | @* Viktor Levandovskyy, viktor.levandovskyy at math.rwth-aachen.de |
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8 | @* Karim Abou Zeid, karim.abou.zeid at rwth-aachen.de |
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9 | |
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10 | Support: Joint projects LE 2697/2-1 and KR 1907/3-1 of the Priority Programme SPP 1489: |
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11 | 'Algorithmische und Experimentelle Methoden in Algebra, Geometrie und Zahlentheorie' |
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12 | of the German DFG (2010-2013) |
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13 | and Project II.6 of the transregional collaborative research centre |
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14 | SFB-TRR 195 'Symbolic Tools in Mathematics and their Application' of the German DFG (from 2017 on) |
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15 | |
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16 | KEYWORDS: finitely presented algebra; Letterplace Groebner basis; K-basis; K-dimension; Hilbert series |
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17 | |
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18 | NOTE: |
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19 | - basering is a Letterplace ring |
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20 | - all intvecs correspond to Letterplace monomials |
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21 | - if a degree bound d is specified, d <= attrib(basering,uptodeg) holds |
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22 | |
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23 | In the procedures below, 'iv' stands for intvec representation |
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24 | and 'lp' for the letterplace representation of monomials |
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25 | |
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26 | OVERVIEW: |
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27 | Given the free associative algebra A = K<x_1,...,x_n> and |
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28 | a (finite or truncated) Groebner basis GB, one is interested in |
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29 | the following data: |
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30 | - the K-dimension of A/<GB> (check for finiteness or explicit value) |
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31 | - the Hilbert series of A/<GB> |
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32 | - the explicit monomial K-basis of A/<GB> |
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33 | In order to determine these, we need |
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34 | - the Ufnarovskij graph induced by GB |
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35 | - the mistletoes of A/<GB> (which are special monomials in a basis) |
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36 | |
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37 | The Ufnarovskij graph is used to determine whether A/<GB> has finite |
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38 | K-dimension. One has to check if the graph contains cycles. |
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39 | For the whole theory we refer to [Ufn]. Given a |
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40 | reduced set of monomials GB one can define the basis tree, whose vertex |
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41 | set V consists of all normal monomials w.r.t. GB. For every two |
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42 | monomials m_1, m_2 in V there is a direct edge from m_1 to m_2, if and |
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43 | only if there exists x_k in {x_1,..,x_n}, such that m_1*x_k = m_2. The |
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44 | set M = {m in V | there is no edge from m to another monomial in V} is |
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45 | called the set of mistletoes. As one can easily see it consists of |
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46 | the endpoints of the graph. Since there is a unique path to every |
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47 | monomial in V, the whole graph can be described only from the knowledge |
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48 | of the mistletoes. Note that V corresponds to a basis of A/<GB>, so |
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49 | knowing the mistletoes we know a K-basis. The name mistletoes was given |
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50 | to those points because of these miraculous value and the algorithm is |
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51 | named sickle, because a sickle is the tool to harvest mistletoes. |
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52 | For more details see [Stu]. This package uses the Letterplace |
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53 | format introduced by [LL09]. The algebra can either be represented as a |
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54 | Letterplace ring or via integer vectors: Every variable will only be |
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55 | represented by its number, so variable one is represented as 1, |
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56 | variable two as 2 and so on. The monomial x_1*x_3*x_2 for example will |
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57 | be stored as (1,3,2). Multiplication is concatenation. Note that the |
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58 | approach in this library does not need an algorithm for computing the normal |
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59 | form. Note that fpa is an acronym for Finitely Presented Algebra. |
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60 | |
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61 | |
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62 | REFERENCES: |
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63 | [Ufn] V. Ufnarovskij: Combinatorical and asymptotic methods in algebra, 1990. |
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64 | [LL09] R. La Scala, V. Levandovskyy: Letterplace ideals and non-commutative |
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65 | Groebner bases, Journal of Symbolic Computation, 2009. |
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66 | [Stu] G. Studzinski: Dimension computations in non-commutative, |
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67 | associative algebras, Diploma thesis, RWTH Aachen, 2010. |
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68 | |
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69 | PROCEDURES: |
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70 | lpKDimCheck(G); checks whether the K-dimension of A/<G> is finite |
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71 | lpKDim(G[,d,n]); computes the K-dimension of A/<G> |
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72 | lpMonomialBasis(d, donly, J); computes a list of monomials not contained in J |
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73 | lpHilbert(G[,d,n]); computes the truncated Hilbert series of A/<G> |
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74 | lpSickleDim(G[,d,n]); computes the mistletoes and the K-dimension of A/<G> |
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75 | |
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76 | SEE ALSO: freegb_lib, fpaprops_lib, ncHilb_lib |
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77 | "; |
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78 | |
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79 | LIB "freegb.lib"; //for letterplace rings |
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80 | LIB "general.lib";//for sorting mistletoes |
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81 | |
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82 | ///////////////////////////////////////////////////////// |
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83 | |
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84 | /* very fast and cheap test of consistency and functionality |
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85 | DO NOT make it static ! |
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86 | after adding the new proc, add it here */ |
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87 | proc tstfpadim() |
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88 | { |
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89 | example ivDHilbert; |
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90 | example ivDHilbertSickle; |
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91 | example ivKDimCheck; |
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92 | example ivHilbert; |
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93 | example ivKDim; |
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94 | example ivMis2Base; |
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95 | example ivMis2Dim; |
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96 | example ivOrdMisLex; |
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97 | example ivSickle; |
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98 | example ivSickleHil; |
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99 | example ivSickleDim; |
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100 | example lpDHilbert; |
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101 | example lpDHilbertSickle; |
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102 | example lpHilbert; |
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103 | example lpKDimCheck; |
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104 | example lpKDim; |
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105 | example lpMis2Base; |
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106 | example lpMis2Dim; |
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107 | example lpOrdMisLex; |
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108 | example lpSickle; |
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109 | example lpSickleHil; |
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110 | example lpSickleDim; |
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111 | example sickle; |
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112 | example lpMonomialBasis; |
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113 | } |
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114 | |
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115 | |
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116 | //--------------- auxiliary procedures ------------------ |
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117 | |
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118 | static proc allVars(list L, intvec P, int n) |
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119 | "USAGE: allVars(L,P,n); L a list of intmats, P an intvec, n an integer |
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120 | RETURN: int, 0 if all variables are contained in the quotient algebra, 1 otherwise |
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121 | " |
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122 | {int i,j,r; |
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123 | intvec V; |
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124 | for (i = 1; i <= size(P); i++) {if (P[i] == 1){ j = i; break;}} |
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125 | V = L[j][1..nrows(L[j]),1]; |
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126 | for (i = 1; i <= n; i++) {if (isInVec(i,V) == 0) {r = 1; break;}} |
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127 | if (r == 0) {return(1);} |
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128 | else {return(0);} |
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129 | } |
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130 | |
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131 | static proc checkAssumptions(int d, list L) |
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132 | "PURPOSE: Checks, if all the Assumptions are holding |
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133 | " |
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134 | {if (!isFreeAlgebra(basering)) {ERROR("Basering is not a Letterplace ring!");} |
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135 | if (d > lpDegBound(basering)) {ERROR("Specified degree bound exceeds ring parameter!");} |
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136 | int i; |
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137 | for (i = 1; i <= size(L); i++) |
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138 | {if (entryViolation(L[i], lpVarBlockSize(basering))) |
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139 | {ERROR("Not allowed monomial/intvec found!");} |
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140 | } |
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141 | return(); |
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142 | } |
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143 | |
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144 | static proc createStartMat(int d, int n) |
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145 | "USAGE: createStartMat(d,n); d, n integers |
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146 | RETURN: intmat |
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147 | PURPOSE:Creating the intmat with all normal monomials in n variables and of degree d to start with |
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148 | NOTE: d has to be > 0 |
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149 | " |
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150 | {intmat M[(n^d)][d]; |
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151 | int i1,i2,i3,i4; |
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152 | for (i1 = 1; i1 <= d; i1++) //Spalten |
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153 | {i2 = 1; //durchlaeuft Zeilen |
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154 | while (i2 <= (n^d)) |
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155 | {for (i3 = 1; i3 <= n; i3++) |
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156 | {for (i4 = 1; i4 <= (n^(i1-1)); i4++) |
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157 | {M[i2,i1] = i3; |
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158 | i2 = i2 + 1; |
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159 | } |
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160 | } |
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161 | } |
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162 | } |
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163 | return(M); |
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164 | } |
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165 | |
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166 | static proc createStartMat1(int n, intmat M) |
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167 | "USAGE: createStartMat1(n,M); n an integer, M an intmat |
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168 | RETURN: intmat, with all variables except those in M |
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169 | " |
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170 | {int i; |
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171 | intvec V,Vt; |
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172 | V = M[(1..nrows(M)),1]; |
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173 | for (i = 1; i <= size(V); i++) {if (isInVec(i,V) == 0) {Vt = Vt,i;}} |
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174 | if (Vt == 0) {intmat S; return(S);} |
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175 | else {Vt = Vt[2..size(Vt)]; intmat S [size(Vt)][1]; S[1..size(Vt),1] = Vt; return(S);} |
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176 | } |
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177 | |
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178 | static proc entryViolation(intmat M, int n) |
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179 | "PURPOSE:checks, if all entries in M are variable-related |
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180 | " |
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181 | {int i,j; |
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182 | for (i = 1; i <= nrows(M); i++) |
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183 | {for (j = 1; j <= ncols(M); j++) |
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184 | {if(!((1<=M[i,j])&&(M[i,j]<=n))) {return(1);}} |
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185 | } |
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186 | return(0); |
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187 | } |
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188 | |
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189 | static proc findDimen(intvec V, int n, list L, intvec P, list #) |
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190 | "USAGE: findDimen(V,n,L,P,degbound); V,P intvecs, n, an integer, L a list, |
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191 | @* degbound an optional integer |
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192 | RETURN: int |
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193 | PURPOSE:Compute the K-dimension of the quotient algebra |
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194 | " |
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195 | {int degbound = 0; |
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196 | if (size(#) > 0) {if (#[1] > 0) {degbound = #[1];}} |
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197 | int dimen,i,j,w,it; |
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198 | intvec Vt,Vt2; |
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199 | module M; |
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200 | if (degbound == 0) |
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201 | {for (i = 1; i <= n; i++) |
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202 | {Vt = V, i; w = 0; |
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203 | for (j = 1; j<= size(P); j++) |
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204 | {if (P[j] <= size(Vt)) |
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205 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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206 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
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207 | } |
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208 | } |
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209 | if (w == 0) |
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210 | {vector Vtt; |
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211 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
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212 | M = M,Vtt; |
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213 | kill Vtt; |
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214 | } |
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215 | } |
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216 | if (size(M) == 0) {return(0);} |
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217 | else |
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218 | {M = simplify(M,2); |
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219 | for (i = 1; i <= size(M); i++) |
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220 | {kill Vt; intvec Vt; |
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221 | for (j =1; j <= size(M[i]); j++){Vt[j] = int(leadcoef(M[i][j]));} |
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222 | dimen = dimen + 1 + findDimen(Vt,n,L,P); |
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223 | } |
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224 | return(dimen); |
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225 | } |
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226 | } |
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227 | else |
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228 | {if (size(V) > degbound) {ERROR("monomial exceeds degreebound");} |
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229 | if (size(V) == degbound) {return(0);} |
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230 | for (i = 1; i <= n; i++) |
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231 | {Vt = V, i; w = 0; |
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232 | for (j = 1; j<= size(P); j++) |
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233 | {if (P[j] <= size(Vt)) |
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234 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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235 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
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236 | } |
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237 | } |
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238 | if (w == 0) {vector Vtt; |
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239 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
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240 | M = M,Vtt; |
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241 | kill Vtt; |
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242 | } |
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243 | } |
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244 | if (size(M) == 0) {return(0);} |
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245 | else |
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246 | {M = simplify(M,2); |
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247 | for (i = 1; i <= size(M); i++) |
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248 | {kill Vt; intvec Vt; |
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249 | for (j =1; j <= size(M[i]); j++){Vt[j] = int(leadcoef(M[i][j]));} |
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250 | dimen = dimen + 1 + findDimen(Vt,n,L,P,degbound); |
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251 | } |
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252 | return(dimen); |
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253 | } |
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254 | } |
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255 | } |
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256 | |
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257 | static proc findCycle(intvec V, list L, intvec P, int n, int ld, module M) |
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258 | "USAGE: |
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259 | RETURN: int, 1 if Ufn-graph contains a cycle, or 0 otherwise |
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260 | PURPOSE:Searching the Ufnarovskij graph for cycles |
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261 | " |
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262 | {int i,j,w,r;intvec Vt,Vt2; |
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263 | int it, it2; |
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264 | if (size(V) < ld) |
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265 | {for (i = 1; i <= n; i++) |
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266 | {Vt = V,i; w = 0; |
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267 | for (j = 1; j <= size(P); j++) |
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268 | {if (P[j] <= size(Vt)) |
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269 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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270 | if (isInMat(Vt2,L[j]) > 0) |
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271 | {w = 1; break;} |
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272 | } |
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273 | } |
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274 | if (w == 0) {r = findCycle(Vt,L,P,n,ld,M);} |
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275 | if (r == 1) {break;} |
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276 | } |
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277 | return(r); |
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278 | } |
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279 | else |
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280 | {j = size(M); |
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281 | if (j > 0) |
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282 | { |
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283 | intmat Mt[j][nrows(M)]; |
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284 | for (it = 1; it <= j; it++) |
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285 | { for(it2 = 1; it2 <= nrows(M);it2++) |
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286 | {Mt[it,it2] = int(leadcoef(M[it2,it]));} |
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287 | } |
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288 | Vt = V[(size(V)-ld+1)..size(V)]; |
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289 | //Mt; type(Mt);Vt;type(Vt); |
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290 | if (isInMat(Vt,Mt) > 0) {return(1);} |
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291 | else |
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292 | {vector Vtt; |
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293 | for (it =1; it <= size(Vt); it++) |
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294 | {Vtt = Vtt + Vt[it]*gen(it);} |
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295 | M = M,Vtt; |
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296 | kill Vtt; |
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297 | for (i = 1; i <= n; i++) |
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298 | {Vt = V,i; w = 0; |
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299 | for (j = 1; j <= size(P); j++) |
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300 | {if (P[j] <= size(Vt)) |
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301 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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302 | //L[j]; type(L[j]);Vt2;type(Vt2); |
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303 | if (isInMat(Vt2,L[j]) > 0) |
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304 | {w = 1; break;} |
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305 | } |
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306 | } |
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307 | if (w == 0) {r = findCycle(Vt,L,P,n,ld,M);} |
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308 | if (r == 1) {break;} |
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309 | } |
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310 | return(r); |
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311 | } |
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312 | } |
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313 | else |
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314 | { Vt = V[(size(V)-ld+1)..size(V)]; |
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315 | vector Vtt; |
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316 | for (it = 1; it <= size(Vt); it++) |
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317 | {Vtt = Vtt + Vt[it]*gen(it);} |
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318 | M = Vtt; |
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319 | kill Vtt; |
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320 | for (i = 1; i <= n; i++) |
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321 | {Vt = V,i; w = 0; |
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322 | for (j = 1; j <= size(P); j++) |
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323 | {if (P[j] <= size(Vt)) |
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324 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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325 | //L[j]; type(L[j]);Vt2;type(Vt2); |
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326 | if (isInMat(Vt2,L[j]) > 0) |
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327 | {w = 1; break;} |
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328 | } |
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329 | } |
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330 | if (w == 0) {r = findCycle(Vt,L,P,n,ld,M);} |
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331 | if (r == 1) {break;} |
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332 | } |
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333 | return(r); |
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334 | } |
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335 | } |
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336 | } |
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337 | |
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338 | |
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339 | static proc findCycleDFS(int i, intmat T, intvec V) |
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340 | " |
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341 | PURPOSE: |
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342 | this is a classical deep-first search for cycles contained in a graph given by an intmat |
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343 | " |
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344 | { |
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345 | intvec rV; |
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346 | int k,k1,t; |
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347 | int j = V[size(V)]; |
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348 | if (T[j,i] > 0) {return(V);} |
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349 | else |
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350 | { |
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351 | for (k = 1; k <= ncols(T); k++) |
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352 | { |
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353 | t = 0; |
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354 | if (T[j,k] > 0) |
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355 | { |
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356 | for (k1 = 1; k1 <= size(V); k1++) {if (V[k1] == k) {t = 1; break;}} |
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357 | if (t == 0) |
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358 | { |
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359 | rV = V; |
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360 | rV[size(rV)+1] = k; |
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361 | rV = findCycleDFS(i,T,rV); |
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362 | if (rV[1] > -1) {return(rV);} |
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363 | } |
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364 | } |
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365 | } |
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366 | } |
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367 | return(intvec(-1)); |
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368 | } |
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369 | |
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370 | |
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371 | |
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372 | static proc findHCoeff(intvec V,int n,list L,intvec P,intvec H,list #) |
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373 | "USAGE: findHCoeff(V,n,L,P,H,degbound); L a list of intmats, degbound an integer |
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374 | RETURN: intvec |
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375 | PURPOSE:Compute the coefficient of the Hilbert series (upto degree degbound) |
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376 | NOTE: Starting with a part of the Hilbert series we change the coefficient |
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377 | @* depending on how many basis elements we found on the actual branch |
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378 | " |
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379 | {int degbound = 0; |
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380 | if (size(#) > 0){if (#[1] > 0){degbound = #[1];}} |
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381 | int i,w,j,it; |
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382 | int h1 = 0; |
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383 | intvec Vt,Vt2,H1; |
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384 | module M; |
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385 | if (degbound == 0) |
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386 | {for (i = 1; i <= n; i++) |
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387 | {Vt = V, i; w = 0; |
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388 | for (j = 1; j<= size(P); j++) |
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389 | {if (P[j] <= size(Vt)) |
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390 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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391 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
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392 | } |
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393 | } |
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394 | if (w == 0) |
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395 | {vector Vtt; |
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396 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
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397 | M = M,Vtt; |
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398 | kill Vtt; |
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399 | } |
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400 | } |
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401 | if (size(M) == 0) {return(H);} |
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402 | else |
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403 | {M = simplify(M,2); |
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404 | for (i = 1; i <= size(M); i++) |
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405 | {kill Vt; intvec Vt; |
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406 | for (j =1; j <= size(M[i]); j++) {Vt[j] = int(leadcoef(M[i][j]));} |
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407 | h1 = h1 + 1; H1 = findHCoeff(Vt,n,L,P,H1); |
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408 | } |
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409 | if (size(H1) < (size(V)+2)) {H1[(size(V)+2)] = h1;} |
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410 | else {H1[(size(V)+2)] = H1[(size(V)+2)] + h1;} |
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411 | H1 = H1 + H; |
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412 | return(H1); |
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413 | } |
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414 | } |
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415 | else |
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416 | {if (size(V) > degbound) {ERROR("monomial exceeds degreebound");} |
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417 | if (size(V) == degbound) {return(H);} |
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418 | for (i = 1; i <= n; i++) |
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419 | {Vt = V, i; w = 0; |
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420 | for (j = 1; j<= size(P); j++) |
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421 | {if (P[j] <= size(Vt)) |
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422 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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423 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
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424 | } |
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425 | } |
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426 | if (w == 0) |
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427 | {vector Vtt; |
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428 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
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429 | M = M,Vtt; |
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430 | kill Vtt; |
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431 | } |
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432 | } |
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433 | if (size(M) == 0) {return(H);} |
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434 | else |
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435 | {M = simplify(M,2); |
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436 | for (i = 1; i <= size(M); i++) |
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437 | {kill Vt; intvec Vt; |
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438 | for (j =1; j <= size(M[i]); j++) |
---|
439 | {Vt[j] = int(leadcoef(M[i][j]));} |
---|
440 | h1 = h1 + 1; H1 = findHCoeff(Vt,n,L,P,H1,degbound); |
---|
441 | } |
---|
442 | if (size(H1) < (size(V)+2)) { H1[(size(V)+2)] = h1;} |
---|
443 | else {H1[(size(V)+2)] = H1[(size(V)+2)] + h1;} |
---|
444 | H1 = H1 + H; |
---|
445 | return(H1); |
---|
446 | } |
---|
447 | } |
---|
448 | } |
---|
449 | |
---|
450 | static proc findHCoeffMis(intvec V, int n, list L, intvec P, list R,list #) |
---|
451 | "USAGE: findHCoeffMis(V,n,L,P,R,degbound); degbound an optional integer, L a |
---|
452 | @* list of Intmats, R |
---|
453 | RETURN: list |
---|
454 | PURPOSE:Compute the coefficients of the Hilbert series and the Mistletoes all |
---|
455 | @* at once |
---|
456 | " |
---|
457 | {int degbound = 0; |
---|
458 | if (size(#) > 0) {if (#[1] > 0) {degbound = #[1];}} |
---|
459 | int i,w,j,h1; |
---|
460 | intvec Vt,Vt2,H1; int it; |
---|
461 | module M; |
---|
462 | if (degbound == 0) |
---|
463 | {for (i = 1; i <= n; i++) |
---|
464 | {Vt = V, i; w = 0; |
---|
465 | for (j = 1; j<= size(P); j++) |
---|
466 | {if (P[j] <= size(Vt)) |
---|
467 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
468 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
---|
469 | } |
---|
470 | } |
---|
471 | if (w == 0) |
---|
472 | {vector Vtt; |
---|
473 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
474 | M = M,Vtt; |
---|
475 | kill Vtt; |
---|
476 | } |
---|
477 | } |
---|
478 | if (size(M) == 0) {if (size(R) < 2){R[2] = list(V);} else {R[2] = R[2] + list(V);} return(R);} |
---|
479 | else |
---|
480 | {M = simplify(M,2); |
---|
481 | for (i = 1; i <= size(M); i++) |
---|
482 | {kill Vt; intvec Vt; |
---|
483 | for (j =1; j <= size(M[i]); j++) |
---|
484 | {Vt[j] = int(leadcoef(M[i][j]));} |
---|
485 | if (size(R[1]) < (size(V)+2)) { R[1][(size(V)+2)] = 1;} |
---|
486 | else |
---|
487 | {R[1][(size(V)+2)] = R[1][(size(V)+2)] + 1;} |
---|
488 | R = findHCoeffMis(Vt,n,L,P,R); |
---|
489 | } |
---|
490 | return(R); |
---|
491 | } |
---|
492 | } |
---|
493 | else |
---|
494 | {if (size(V) > degbound) {ERROR("monomial exceeds degreebound");} |
---|
495 | if (size(V) == degbound) |
---|
496 | {if (size(R) < 2){R[2] = list (V);} |
---|
497 | else{R[2] = R[2] + list (V);} |
---|
498 | return(R); |
---|
499 | } |
---|
500 | for (i = 1; i <= n; i++) |
---|
501 | {Vt = V, i; w = 0; |
---|
502 | for (j = 1; j<= size(P); j++) |
---|
503 | {if (P[j] <= size(Vt)) |
---|
504 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
505 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
---|
506 | } |
---|
507 | } |
---|
508 | if (w == 0) |
---|
509 | {vector Vtt; |
---|
510 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
511 | M = M,Vtt; |
---|
512 | kill Vtt; |
---|
513 | } |
---|
514 | } |
---|
515 | if (size(M) == 0) {if (size(R) < 2){R[2] = list(V);} else {R[2] = R[2] + list(V);} return(R);} |
---|
516 | else |
---|
517 | {M = simplify(M,2); |
---|
518 | for (i = 1; i <= ncols(M); i++) |
---|
519 | {kill Vt; intvec Vt; |
---|
520 | for (j =1; j <= size(M[i]); j++) |
---|
521 | {Vt[j] = int(leadcoef(M[i][j]));} |
---|
522 | if (size(R[1]) < (size(V)+2)) { R[1][(size(V)+2)] = 1;} |
---|
523 | else |
---|
524 | {R[1][(size(V)+2)] = R[1][(size(V)+2)] + 1;} |
---|
525 | R = findHCoeffMis(Vt,n,L,P,R,degbound); |
---|
526 | } |
---|
527 | return(R); |
---|
528 | } |
---|
529 | } |
---|
530 | } |
---|
531 | |
---|
532 | |
---|
533 | static proc findMisDim(intvec V,int n,list L,intvec P,list R,list #) |
---|
534 | "USAGE: |
---|
535 | RETURN: list |
---|
536 | PURPOSE:Compute the K-dimension and the Mistletoes all at once |
---|
537 | " |
---|
538 | {int degbound = 0; |
---|
539 | if (size(#) > 0) {if (#[1] > 0) {degbound = #[1];}} |
---|
540 | int dimen,i,j,w; |
---|
541 | intvec Vt,Vt2; int it; |
---|
542 | module M; |
---|
543 | if (degbound == 0) |
---|
544 | {for (i = 1; i <= n; i++) |
---|
545 | {Vt = V, i; w = 0; |
---|
546 | for (j = 1; j<= size(P); j++) |
---|
547 | {if (P[j] <= size(Vt)) |
---|
548 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
549 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
---|
550 | } |
---|
551 | } |
---|
552 | if (w == 0) |
---|
553 | {vector Vtt; |
---|
554 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
555 | M = M,Vtt; |
---|
556 | kill Vtt; |
---|
557 | } |
---|
558 | } |
---|
559 | if (size(M) == 0) |
---|
560 | {if (size(R) < 2){R[2] = list (V);} |
---|
561 | else{R[2] = R[2] + list(V);} |
---|
562 | return(R); |
---|
563 | } |
---|
564 | else |
---|
565 | {M = simplify(M,2); |
---|
566 | for (i = 1; i <= size(M); i++) |
---|
567 | {kill Vt; intvec Vt; |
---|
568 | for (j =1; j <= size(M[i]); j++){Vt[j] = int(leadcoef(M[i][j]));} |
---|
569 | R[1] = R[1] + 1; R = findMisDim(Vt,n,L,P,R); |
---|
570 | } |
---|
571 | return(R); |
---|
572 | } |
---|
573 | } |
---|
574 | else |
---|
575 | {if (size(V) > degbound) {ERROR("monomial exceeds degreebound");} |
---|
576 | if (size(V) == degbound) |
---|
577 | {if (size(R) < 2){R[2] = list (V);} |
---|
578 | else{R[2] = R[2] + list (V);} |
---|
579 | return(R); |
---|
580 | } |
---|
581 | for (i = 1; i <= n; i++) |
---|
582 | {Vt = V, i; w = 0; |
---|
583 | for (j = 1; j<= size(P); j++) |
---|
584 | {if (P[j] <= size(Vt)) |
---|
585 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
586 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
---|
587 | } |
---|
588 | } |
---|
589 | if (w == 0) |
---|
590 | {vector Vtt; |
---|
591 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
592 | M = M,Vtt; |
---|
593 | kill Vtt; |
---|
594 | } |
---|
595 | } |
---|
596 | if (size(M) == 0) |
---|
597 | {if (size(R) < 2){R[2] = list (V);} |
---|
598 | else{R[2] = R[2] + list(V);} |
---|
599 | return(R); |
---|
600 | } |
---|
601 | else |
---|
602 | {M = simplify(M,2); |
---|
603 | for (i = 1; i <= size(M); i++) |
---|
604 | {kill Vt; intvec Vt; |
---|
605 | for (j =1; j <= size(M[i]); j++){Vt[j] = int(leadcoef(M[i][j]));} |
---|
606 | R[1] = R[1] + 1; R = findMisDim(Vt,n,L,P,R,degbound); |
---|
607 | } |
---|
608 | return(R); |
---|
609 | } |
---|
610 | } |
---|
611 | } |
---|
612 | |
---|
613 | |
---|
614 | static proc findmistletoes(intvec V, int n, list L, intvec P, list #) |
---|
615 | "USAGE: findmistletoes(V,n,L,P,degbound); V a normal word, n the number of |
---|
616 | @* variables, L the GB, P the occuring degrees, |
---|
617 | @* and degbound the (optional) degreebound |
---|
618 | RETURN: list |
---|
619 | PURPOSE:Compute mistletoes starting in V |
---|
620 | NOTE: V has to be normal w.r.t. L, it will not be checked for being so |
---|
621 | " |
---|
622 | {int degbound = 0; |
---|
623 | if (size(#) > 0) {if (#[1] > 0) {degbound = #[1];}} |
---|
624 | list R; intvec Vt,Vt2; int it; |
---|
625 | int i,j; |
---|
626 | module M; |
---|
627 | if (degbound == 0) |
---|
628 | {int w; |
---|
629 | for (i = 1; i <= n; i++) |
---|
630 | {Vt = V,i; w = 0; |
---|
631 | for (j = 1; j <= size(P); j++) |
---|
632 | {if (P[j] <= size(Vt)) |
---|
633 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
634 | if (isInMat(Vt2,L[j]) > 0) |
---|
635 | {w = 1; break;} |
---|
636 | } |
---|
637 | } |
---|
638 | if (w == 0) |
---|
639 | {vector Vtt; |
---|
640 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
641 | M = M,Vtt; |
---|
642 | kill Vtt; |
---|
643 | } |
---|
644 | } |
---|
645 | if (size(M)==0) {R = V; return(R);} |
---|
646 | else |
---|
647 | {M = simplify(M,2); |
---|
648 | for (i = 1; i <= size(M); i++) |
---|
649 | {kill Vt; intvec Vt; |
---|
650 | for (j =1; j <= size(M[i]); j++){Vt[j] = int(leadcoef(M[i][j]));} |
---|
651 | R = R + findmistletoes(Vt,n,L,P); |
---|
652 | } |
---|
653 | return(R); |
---|
654 | } |
---|
655 | } |
---|
656 | else |
---|
657 | {if (size(V) > degbound) {ERROR("monomial exceeds degreebound");} |
---|
658 | if (size(V) == degbound) {R = V; return(R);} |
---|
659 | int w; |
---|
660 | for (i = 1; i <= n; i++) |
---|
661 | {Vt = V,i; w = 0; |
---|
662 | for (j = 1; j <= size(P); j++) |
---|
663 | {if (P[j] <= size(Vt)) |
---|
664 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
665 | if (isInMat(Vt2,L[j]) > 0){w = 1; break;} |
---|
666 | } |
---|
667 | } |
---|
668 | if (w == 0) |
---|
669 | {vector Vtt; |
---|
670 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
671 | M = M,Vtt; |
---|
672 | kill Vtt; |
---|
673 | } |
---|
674 | } |
---|
675 | if (size(M) == 0) {R = V; return(R);} |
---|
676 | else |
---|
677 | {M = simplify(M,2); |
---|
678 | for (i = 1; i <= ncols(M); i++) |
---|
679 | {kill Vt; intvec Vt; |
---|
680 | for (j =1; j <= size(M[i]); j++) |
---|
681 | {Vt[j] = int(leadcoef(M[i][j]));} |
---|
682 | //Vt; typeof(Vt); size(Vt); |
---|
683 | R = R + findmistletoes(Vt,n,L,P,degbound); |
---|
684 | } |
---|
685 | return(R); |
---|
686 | } |
---|
687 | } |
---|
688 | } |
---|
689 | |
---|
690 | static proc growthAlg(intmat T, list #) |
---|
691 | " |
---|
692 | real algorithm for checking the growth of an algebra |
---|
693 | " |
---|
694 | { |
---|
695 | int s = 1; |
---|
696 | if (size(#) > 0) { s = #[1];} |
---|
697 | int j; |
---|
698 | int n = ncols(T); |
---|
699 | intvec NV,C; NV[n] = 0; int m,i; |
---|
700 | intmat T2[n][n] = T[1..n,1..n]; intmat N[n][n]; |
---|
701 | if (T2 == N) |
---|
702 | { |
---|
703 | for (i = 1; i <= n; i++) |
---|
704 | { |
---|
705 | if (m < T[n+1,i]) { m = T[n+1,i];} |
---|
706 | } |
---|
707 | return(m); |
---|
708 | } |
---|
709 | |
---|
710 | //first part: the diagonals |
---|
711 | for (i = s; i <= n; i++) |
---|
712 | { |
---|
713 | if (T[i,i] > 0) |
---|
714 | { |
---|
715 | if ((T[i,i] >= 1) && (T[n+1,i] > 0)) {return(-1);} |
---|
716 | if ((T[i,i] == 1) && (T[n+1,i] == 0)) |
---|
717 | { |
---|
718 | T[i,i] = 0; |
---|
719 | T[n+1,i] = 1; |
---|
720 | return(growthAlg(T)); |
---|
721 | } |
---|
722 | } |
---|
723 | } |
---|
724 | |
---|
725 | //second part: searching for the last but one vertices |
---|
726 | T2 = T2*T2; |
---|
727 | for (i = s; i <= n; i++) |
---|
728 | { |
---|
729 | if ((intvec(T[i,1..n]) <> intvec(0)) && (intvec(T2[i,1..n]) == intvec(0))) |
---|
730 | { |
---|
731 | for (j = 1; j <= n; j++) |
---|
732 | { |
---|
733 | if ((T[i,j] > 0) && (m < T[n+1,j])) {m = T[n+1,j];} |
---|
734 | } |
---|
735 | T[n+1,i] = T[n+1,i] + m; |
---|
736 | T[i,1..n] = NV; |
---|
737 | return(growthAlg(T)); |
---|
738 | } |
---|
739 | } |
---|
740 | m = 0; |
---|
741 | |
---|
742 | //third part: searching for circles |
---|
743 | for (i = s; i <= n; i++) |
---|
744 | { |
---|
745 | T2 = T[1..n,1..n]; |
---|
746 | C = findCycleDFS(i,T2, intvec(i)); |
---|
747 | if (C[1] > 0) |
---|
748 | { |
---|
749 | for (j = 2; j <= size(C); j++) |
---|
750 | { |
---|
751 | T[i,1..n] = T[i,1..n] + T[C[j],1..n]; |
---|
752 | T[C[j],1..n] = NV; |
---|
753 | } |
---|
754 | for (j = 2; j <= size(C); j++) |
---|
755 | { |
---|
756 | T[1..n,i] = T[1..n,i] + T[1..n,C[j]]; |
---|
757 | T[1..n,C[j]] = NV; |
---|
758 | } |
---|
759 | T[i,i] = T[i,i] - size(C) + 1; |
---|
760 | m = 0; |
---|
761 | for (j = 1; j <= size(C); j++) |
---|
762 | { |
---|
763 | m = m + T[n+1,C[j]]; |
---|
764 | } |
---|
765 | for (j = 1; j <= size(C); j++) |
---|
766 | { |
---|
767 | T[n+1,C[j]] = m; |
---|
768 | } |
---|
769 | return(growthAlg(T,i)); |
---|
770 | } |
---|
771 | else {ERROR("No Cycle found, something seems wrong! Please contact the authors.");} |
---|
772 | } |
---|
773 | |
---|
774 | m = 0; |
---|
775 | for (i = 1; i <= n; i++) |
---|
776 | { |
---|
777 | if (m < T[n+1,i]) |
---|
778 | { |
---|
779 | m = T[n+1,i]; |
---|
780 | } |
---|
781 | } |
---|
782 | return(m); |
---|
783 | } |
---|
784 | |
---|
785 | static proc GlDimSuffix(intvec v, intvec g) |
---|
786 | { |
---|
787 | //Computes the shortest r such that g is a suffix for vr |
---|
788 | //only valid for lex orderings? |
---|
789 | intvec r,gt,vt,lt,g2; |
---|
790 | int lg,lv,l,i,c,f; |
---|
791 | lg = size(g); lv = size(v); |
---|
792 | if (lg <= lv) |
---|
793 | { |
---|
794 | l = lv-lg; |
---|
795 | } |
---|
796 | else |
---|
797 | { |
---|
798 | l = 0; g2 = g[(lv+1)..lg]; |
---|
799 | g = g[1..lv]; lg = size(g); |
---|
800 | c = 1; |
---|
801 | } |
---|
802 | while (l < lv) |
---|
803 | { |
---|
804 | vt = v[(l+1)..lv]; |
---|
805 | gt = g[1..(lv-l)]; |
---|
806 | lt = size(gt); |
---|
807 | for (i = 1; i <= lt; i++) |
---|
808 | { |
---|
809 | if (vt[i]<>gt[i]) {l++; break;} |
---|
810 | } |
---|
811 | if (lt <=i ) { f = 1; break;} |
---|
812 | } |
---|
813 | if (f == 0) {return(g);} |
---|
814 | r = g[(lv-l+1)..lg]; |
---|
815 | if (c == 1) {r = r,g2;} |
---|
816 | return(r); |
---|
817 | } |
---|
818 | |
---|
819 | static proc isNormal(intvec V, list G) |
---|
820 | { |
---|
821 | int i,j,k,l; |
---|
822 | k = 0; |
---|
823 | for (i = 1; i <= size(G); i++) |
---|
824 | { |
---|
825 | if ( size(G[i]) <= size(V) ) |
---|
826 | { |
---|
827 | while ( size(G[i])+k <= size(V) ) |
---|
828 | { |
---|
829 | if ( G[i] == V[(1+k)..size(V)] ) {return(1);} |
---|
830 | } |
---|
831 | } |
---|
832 | } |
---|
833 | return(0); |
---|
834 | } |
---|
835 | |
---|
836 | static proc findDChain(list L) |
---|
837 | { |
---|
838 | list Li; int i,j; |
---|
839 | for (i = 1; i <= size(L); i++) {Li[i] = size(L[i]);} |
---|
840 | Li = sort(Li); Li = Li[1]; |
---|
841 | return(Li[size(Li)]); |
---|
842 | } |
---|
843 | |
---|
844 | static proc isInList(intvec V, list L) |
---|
845 | "USAGE: isInList(V,L); V an intvec, L a list of intvecs |
---|
846 | RETURN: int |
---|
847 | PURPOSE:Finding the position of V in L, returns 0, if V is not in M |
---|
848 | " |
---|
849 | {int i,n; |
---|
850 | n = 0; |
---|
851 | for (i = 1; i <= size(L); i++) {if (L[i] == V) {n = i; break;}} |
---|
852 | return(n); |
---|
853 | } |
---|
854 | |
---|
855 | static proc isInMat(intvec V, intmat M) |
---|
856 | "USAGE: isInMat(V,M);V an intvec, M an intmat |
---|
857 | RETURN: int |
---|
858 | PURPOSE:Finding the position of V in M, returns 0, if V is not in M |
---|
859 | " |
---|
860 | {if (size(V) <> ncols(M)) {return(0);} |
---|
861 | int i; |
---|
862 | intvec Vt; |
---|
863 | for (i = 1; i <= nrows(M); i++) |
---|
864 | {Vt = M[i,1..ncols(M)]; |
---|
865 | if ((V-Vt) == 0){return(i);} |
---|
866 | } |
---|
867 | return(0); |
---|
868 | } |
---|
869 | |
---|
870 | static proc isInVec(int v,intvec V) |
---|
871 | "USAGE: isInVec(v,V); v an integer,V an intvec |
---|
872 | RETURN: int |
---|
873 | PURPOSE:Finding the position of v in V, returns 0, if v is not in V |
---|
874 | " |
---|
875 | {int i,n; |
---|
876 | n = 0; |
---|
877 | for (i = 1; i <= size(V); i++) {if (V[i] == v) {n = i; break;}} |
---|
878 | return(n); |
---|
879 | } |
---|
880 | |
---|
881 | |
---|
882 | static proc isPF(intvec P, intvec I) |
---|
883 | " |
---|
884 | PURPOSE: |
---|
885 | checks, if a word P is a praefix of another word I |
---|
886 | " |
---|
887 | { |
---|
888 | int n = size(P); |
---|
889 | if (n <= 0 || P == 0) {return(1);} |
---|
890 | if (size(I) < n) {return(0);} |
---|
891 | intvec IP = I[1..n]; |
---|
892 | if (IP == P) {return(1);} |
---|
893 | else {return(0);} |
---|
894 | } |
---|
895 | |
---|
896 | // -----------------main procedures---------------------- |
---|
897 | |
---|
898 | static proc lpGraphOfNormalWords(ideal G) |
---|
899 | "USAGE: lpGraphOfNormalWords(G); G a set of monomials in a letterplace ring |
---|
900 | RETURN: intmat |
---|
901 | PURPOSE: Constructs the graph of normal words induced by G |
---|
902 | @*: the adjacency matrix of the graph of normal words induced by G |
---|
903 | ASSUME: - basering is a Letterplace ring |
---|
904 | - G are the leading monomials of a Groebner basis |
---|
905 | " |
---|
906 | { |
---|
907 | // construct the Graph of normal words [Studzinski page 78] |
---|
908 | // construct set of vertices |
---|
909 | int v = lpVarBlockSize(basering); int d = lpDegBound(basering); |
---|
910 | ideal V; poly p,q,w; |
---|
911 | ideal LG = lead(G); |
---|
912 | int i,j,k,b; intvec E,Et; |
---|
913 | for (i = 1; i <= v; i++){V = V, var(i);} |
---|
914 | for (i = 1; i <= size(LG); i++) |
---|
915 | { |
---|
916 | E = leadexp(LG[i]); |
---|
917 | if (E == intvec(0)) {V = V,monomial(intvec(0));} |
---|
918 | else |
---|
919 | { |
---|
920 | for (j = 1; j < d; j++) |
---|
921 | { |
---|
922 | Et = E[(j*v+1)..(d*v)]; |
---|
923 | if (Et == intvec(0)) {break;} |
---|
924 | else {V = V, monomial(Et);} |
---|
925 | } |
---|
926 | } |
---|
927 | } |
---|
928 | V = simplify(V,2+4); |
---|
929 | printf("V = %p", V); |
---|
930 | |
---|
931 | |
---|
932 | // construct incidence matrix |
---|
933 | |
---|
934 | list LV = lpId2ivLi(V); |
---|
935 | intvec Ip,Iw; |
---|
936 | int n = size(V); |
---|
937 | intmat T[n+1][n]; |
---|
938 | for (i = 1; i <= n; i++) |
---|
939 | { |
---|
940 | // printf("for1 (i=%p, n=%p)", i, n); |
---|
941 | p = V[i]; Ip = lp2iv(p); |
---|
942 | for (j = 1; j <= n; j++) |
---|
943 | { |
---|
944 | // printf("for2 (j=%p, n=%p)", j, n); |
---|
945 | k = 1; b = 1; |
---|
946 | q = V[j]; |
---|
947 | w = lpNF(p*q,LG); |
---|
948 | if (w <> 0) |
---|
949 | { |
---|
950 | Iw = lp2iv(w); |
---|
951 | while (k <= n) |
---|
952 | { |
---|
953 | // printf("while (k=%p, n=%p)", k, n); |
---|
954 | if (isPF(LV[k],Iw) > 0) |
---|
955 | {if (isPF(LV[k],Ip) == 0) {b = 0; k = n+1;} else {k++;} |
---|
956 | } |
---|
957 | else {k++;} |
---|
958 | } |
---|
959 | T[i,j] = b; |
---|
960 | // print("Incidence Matrix:"); |
---|
961 | // print(T); |
---|
962 | } |
---|
963 | } |
---|
964 | } |
---|
965 | return(T); |
---|
966 | } |
---|
967 | |
---|
968 | // This proc is deprecated, see lpGkDim() in fpaprops.lib |
---|
969 | /* proc lpGkDim(ideal G) */ |
---|
970 | /* "USAGE: lpGkDim(G); G an ideal in a letterplace ring */ |
---|
971 | /* RETURN: int */ |
---|
972 | /* PURPOSE: Determines the Gelfand Kirillov dimension of A/<G> */ |
---|
973 | /* @*: -1 means it is infinite */ |
---|
974 | /* ASSUME: - basering is a Letterplace ring */ |
---|
975 | /* - G is a Groebner basis */ |
---|
976 | /* NOTE: see fpaprops.lib for a faster and more up to date version of this method */ |
---|
977 | /* " */ |
---|
978 | /* { */ |
---|
979 | /* return(growthAlg(lpGraphOfNormalWords(G))); */ |
---|
980 | /* } */ |
---|
981 | |
---|
982 | static proc ivDHilbert(list L, int n, list #) |
---|
983 | "USAGE: ivDHilbert(L,n[,degbound]); L a list of intmats, n an integer, |
---|
984 | @* degbound an optional integer |
---|
985 | RETURN: list |
---|
986 | PURPOSE:Compute the K-dimension and the Hilbert series |
---|
987 | ASSUME: - basering is a Letterplace ring |
---|
988 | @* - all rows of each intmat correspond to a Letterplace monomial |
---|
989 | @* - if you specify a different degree bound degbound, |
---|
990 | @* degbound <= attrib(basering,uptodeg) holds |
---|
991 | NOTE: - If L is the list returned, then L[1] is an integer corresponding to the |
---|
992 | @* dimension, L[2] is an intvec which contains the coefficients of the |
---|
993 | @* Hilbert series |
---|
994 | @* - If degbound is set, there will be a degree bound added. By default there |
---|
995 | @* is no degree bound |
---|
996 | @* - n is the number of variables |
---|
997 | @* - If I = L[2] is the intvec returned, then I[k] is the (k-1)-th coefficient of |
---|
998 | @* the Hilbert series. |
---|
999 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
1000 | EXAMPLE: example ivDHilbert; shows examples |
---|
1001 | " |
---|
1002 | {int degbound = 0; |
---|
1003 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] > 0){degbound = #[1];}}} |
---|
1004 | checkAssumptions(degbound,L); |
---|
1005 | intvec H; int i,dimen; |
---|
1006 | H = ivHilbert(L,n,degbound); |
---|
1007 | for (i = 1; i <= size(H); i++){dimen = dimen + H[i];} |
---|
1008 | L = dimen,H; |
---|
1009 | return(L); |
---|
1010 | } |
---|
1011 | example |
---|
1012 | { |
---|
1013 | "EXAMPLE:"; echo = 2; |
---|
1014 | ring r = 0,(x,y),dp; |
---|
1015 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1016 | R; |
---|
1017 | setring R; // sets basering to Letterplace ring |
---|
1018 | //some intmats, which contain monomials in intvec representation as rows |
---|
1019 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
1020 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
1021 | print(I1); |
---|
1022 | print(I2); |
---|
1023 | print(J1); |
---|
1024 | print(J2); |
---|
1025 | list G = I1,I2; // ideal, which is already a Groebner basis |
---|
1026 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
1027 | //the procedure without a degree bound |
---|
1028 | ivDHilbert(G,2); |
---|
1029 | // the procedure with degree bound 5 |
---|
1030 | ivDHilbert(I,2,5); |
---|
1031 | } |
---|
1032 | |
---|
1033 | static proc ivDHilbertSickle(list L, int n, list #) |
---|
1034 | "USAGE: ivDHilbertSickle(L,n[,degbound]); L a list of intmats, n an integer, |
---|
1035 | @* degbound an optional integer |
---|
1036 | RETURN: list |
---|
1037 | PURPOSE:Compute the K-dimension, Hilbert series and mistletoes |
---|
1038 | ASSUME: - basering is a Letterplace ring. |
---|
1039 | @* - All rows of each intmat correspond to a Letterplace monomial. |
---|
1040 | @* - If you specify a different degree bound degbound, |
---|
1041 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
1042 | NOTE: - If L is the list returned, then L[1] is an integer, L[2] is an intvec |
---|
1043 | @* which contains the coefficients of the Hilbert series and L[3] |
---|
1044 | @* is a list, containing the mistletoes as intvecs. |
---|
1045 | @* - If degbound is set, a degree bound will be added. By default there |
---|
1046 | @* is no degree bound. |
---|
1047 | @* - n is the number of variables. |
---|
1048 | @* - If I = L[2] is the intvec returned, then I[k] is the (k-1)-th |
---|
1049 | @* coefficient of the Hilbert series. |
---|
1050 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
1051 | EXAMPLE: example ivDHilbertSickle; shows examples |
---|
1052 | " |
---|
1053 | {int degbound = 0; |
---|
1054 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] > 0){degbound = #[1];}}} |
---|
1055 | checkAssumptions(degbound,L); |
---|
1056 | int i,dimen; list R; |
---|
1057 | R = ivSickleHil(L,n,degbound); |
---|
1058 | for (i = 1; i <= size(R[1]); i++){dimen = dimen + R[1][i];} |
---|
1059 | R[3] = R[2]; R[2] = R[1]; R[1] = dimen; |
---|
1060 | return(R); |
---|
1061 | } |
---|
1062 | example |
---|
1063 | { |
---|
1064 | "EXAMPLE:"; echo = 2; |
---|
1065 | ring r = 0,(x,y),dp; |
---|
1066 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1067 | R; |
---|
1068 | setring R; // sets basering to Letterplace ring |
---|
1069 | //some intmats, which contain monomials in intvec representation as rows |
---|
1070 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
1071 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
1072 | print(I1); |
---|
1073 | print(I2); |
---|
1074 | print(J1); |
---|
1075 | print(J2); |
---|
1076 | list G = I1,I2;// ideal, which is already a Groebner basis |
---|
1077 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
1078 | ivDHilbertSickle(G,2); // invokes the procedure without a degree bound |
---|
1079 | ivDHilbertSickle(I,2,3); // invokes the procedure with degree bound 3 |
---|
1080 | } |
---|
1081 | |
---|
1082 | static proc ivKDimCheck(list L, int n) |
---|
1083 | "USAGE: ivKDimCheck(L,n); L a list of intmats, n an integer |
---|
1084 | RETURN: int, 0 if the dimension is finite, or 1 otherwise |
---|
1085 | PURPOSE:Decides, whether the K-dimension is finite or not |
---|
1086 | ASSUME: - basering is a Letterplace ring. |
---|
1087 | @* - All rows of each intmat correspond to a Letterplace monomial. |
---|
1088 | NOTE: - n is the number of variables. |
---|
1089 | EXAMPLE: example ivKDimCheck; shows examples |
---|
1090 | " |
---|
1091 | {checkAssumptions(0,L); |
---|
1092 | int i,r; |
---|
1093 | intvec P,H; |
---|
1094 | for (i = 1; i <= size(L); i++) |
---|
1095 | {P[i] = ncols(L[i]); |
---|
1096 | if (P[i] == 1) {if (isInMat(H,L[i]) > 0) {ERROR("Quotient algebra is trivial");}} |
---|
1097 | } |
---|
1098 | if (size(L) == 0) {ERROR("GB is empty, quotient algebra corresponds to free algebra");} |
---|
1099 | kill H; |
---|
1100 | intmat S; int sd,ld; intvec V; |
---|
1101 | sd = P[1]; ld = P[1]; |
---|
1102 | for (i = 2; i <= size(P); i++) |
---|
1103 | {if (P[i] < sd) {sd = P[i];} |
---|
1104 | if (P[i] > ld) {ld = P[i];} |
---|
1105 | } |
---|
1106 | sd = (sd - 1); ld = ld - 1; |
---|
1107 | if (ld == 0) { return(allVars(L,P,n));} |
---|
1108 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
1109 | else {S = createStartMat(sd,n);} |
---|
1110 | module M; |
---|
1111 | for (i = 1; i <= nrows(S); i++) |
---|
1112 | {V = S[i,1..ncols(S)]; |
---|
1113 | if (findCycle(V,L,P,n,ld,M)) {r = 1; break;} |
---|
1114 | } |
---|
1115 | return(r); |
---|
1116 | } |
---|
1117 | example |
---|
1118 | { |
---|
1119 | "EXAMPLE:"; echo = 2; |
---|
1120 | ring r = 0,(x,y),dp; |
---|
1121 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1122 | R; |
---|
1123 | setring R; // sets basering to Letterplace ring |
---|
1124 | //some intmats, which contain monomials in intvec representation as rows |
---|
1125 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
1126 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
1127 | print(I1); |
---|
1128 | print(I2); |
---|
1129 | print(J1); |
---|
1130 | print(J2); |
---|
1131 | list G = I1,I2;// ideal, which is already a Groebner basis |
---|
1132 | list I = J1,J2; // ideal, which is already a Groebner basis and which |
---|
1133 | ivKDimCheck(G,2); // invokes the procedure, factor is of finite K-dimension |
---|
1134 | ivKDimCheck(I,2); // invokes the procedure, factor is not of finite K-dimension |
---|
1135 | } |
---|
1136 | |
---|
1137 | static proc ivHilbert(list L, int n, list #) |
---|
1138 | "USAGE: ivHilbert(L,n[,degbound]); L a list of intmats, n an integer, |
---|
1139 | @* degbound an optional integer |
---|
1140 | RETURN: intvec, containing the coefficients of the Hilbert series |
---|
1141 | PURPOSE:Compute the Hilbert series |
---|
1142 | ASSUME: - basering is a Letterplace ring. |
---|
1143 | @* - all rows of each intmat correspond to a Letterplace monomial |
---|
1144 | @* - if you specify a different degree bound degbound, |
---|
1145 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
1146 | NOTE: - If degbound is set, a degree bound will be added. By default there |
---|
1147 | @* is no degree bound. |
---|
1148 | @* - n is the number of variables. |
---|
1149 | @* - If I is returned, then I[k] is the (k-1)-th coefficient of the Hilbert |
---|
1150 | @* series. |
---|
1151 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
1152 | EXAMPLE: example ivHilbert; shows examples |
---|
1153 | " |
---|
1154 | {int degbound = 0; |
---|
1155 | if (size(#) > 0) {if (typeof(#[1])=="int"){if (#[1] > 0) {degbound = #[1];}}} |
---|
1156 | intvec P,H; int i; |
---|
1157 | for (i = 1; i <= size(L); i++) |
---|
1158 | {P[i] = ncols(L[i]); |
---|
1159 | if (P[i] == 1) {if ( isInMat(H,L[i]) > 0) {ERROR("Quotient algebra is trivial");}} |
---|
1160 | } |
---|
1161 | if (size(L) == 0) {ERROR("GB is empty, quotient algebra corresponds to free algebra");} |
---|
1162 | H[1] = 1; |
---|
1163 | checkAssumptions(degbound,L); |
---|
1164 | if (degbound == 0) |
---|
1165 | {int sd; |
---|
1166 | intmat S; |
---|
1167 | sd = P[1]; |
---|
1168 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
1169 | sd = (sd - 1); |
---|
1170 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
1171 | else {S = createStartMat(sd,n);} |
---|
1172 | if (intvec(S) == 0) {return(H);} |
---|
1173 | for (i = 1; i <= sd; i++) {H = H,(n^i);} |
---|
1174 | for (i = 1; i <= nrows(S); i++) |
---|
1175 | {intvec St = S[i,1..ncols(S)]; |
---|
1176 | H = findHCoeff(St,n,L,P,H); |
---|
1177 | kill St; |
---|
1178 | } |
---|
1179 | return(H); |
---|
1180 | } |
---|
1181 | else |
---|
1182 | {for (i = 1; i <= size(P); i++) |
---|
1183 | {if (P[i] > degbound) {ERROR("degreebound is too small, GB contains elements of higher degree");}} |
---|
1184 | int sd; |
---|
1185 | intmat S; |
---|
1186 | sd = P[1]; |
---|
1187 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
1188 | sd = (sd - 1); |
---|
1189 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
1190 | else {S = createStartMat(sd,n);} |
---|
1191 | if (intvec(S) == 0) {return(H);} |
---|
1192 | for (i = 1; i <= sd; i++) {H = H,(n^i);} |
---|
1193 | for (i = 1; i <= nrows(S); i++) |
---|
1194 | {intvec St = S[i,1..ncols(S)]; |
---|
1195 | H = findHCoeff(St,n,L,P,H,degbound); |
---|
1196 | kill St; |
---|
1197 | } |
---|
1198 | return(H); |
---|
1199 | } |
---|
1200 | } |
---|
1201 | example |
---|
1202 | { |
---|
1203 | "EXAMPLE:"; echo = 2; |
---|
1204 | ring r = 0,(x,y),dp; |
---|
1205 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1206 | R; |
---|
1207 | setring R; // sets basering to Letterplace ring |
---|
1208 | //some intmats, which contain monomials in intvec representation as rows |
---|
1209 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
1210 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
1211 | print(I1); |
---|
1212 | print(I2); |
---|
1213 | print(J1); |
---|
1214 | print(J2); |
---|
1215 | list G = I1,I2; // ideal, which is already a Groebner basis |
---|
1216 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
1217 | ivHilbert(G,2); // invokes the procedure without any degree bound |
---|
1218 | ivHilbert(I,2,5); // invokes the procedure with degree bound 5 |
---|
1219 | } |
---|
1220 | |
---|
1221 | |
---|
1222 | static proc ivKDim(list L, int n, list #) |
---|
1223 | "USAGE: ivKDim(L,n[,degbound]); L a list of intmats, |
---|
1224 | @* n an integer, degbound an optional integer |
---|
1225 | RETURN: int, the K-dimension of A/<L> |
---|
1226 | PURPOSE:Compute the K-dimension of A/<L> |
---|
1227 | ASSUME: - basering is a Letterplace ring. |
---|
1228 | @* - all rows of each intmat correspond to a Letterplace monomial |
---|
1229 | @* - if you specify a different degree bound degbound, |
---|
1230 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
1231 | NOTE: - If degbound is set, a degree bound will be added. By default there |
---|
1232 | @* is no degree bound. |
---|
1233 | @* - n is the number of variables. |
---|
1234 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
1235 | EXAMPLE: example ivKDim; shows examples |
---|
1236 | " |
---|
1237 | {int degbound = 0; |
---|
1238 | if (size(#) > 0) {if (typeof(#[1])=="int"){if (#[1] > 0) {degbound = #[1];}}} |
---|
1239 | intvec P,H; int i; |
---|
1240 | for (i = 1; i <= size(L); i++) |
---|
1241 | {P[i] = ncols(L[i]); |
---|
1242 | if (P[i] == 1) {if ( isInMat(H,L[i]) > 0) {ERROR("Quotient algebra is trivial");}} |
---|
1243 | } |
---|
1244 | if (size(L) == 0) {ERROR("GB is empty, quotient algebra corresponds to free algebra");} |
---|
1245 | kill H; |
---|
1246 | checkAssumptions(degbound,L); |
---|
1247 | if (degbound == 0) |
---|
1248 | {int sd; int dimen = 1; |
---|
1249 | intmat S; |
---|
1250 | sd = P[1]; |
---|
1251 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
1252 | sd = (sd - 1); |
---|
1253 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
1254 | else {S = createStartMat(sd,n);} |
---|
1255 | if (intvec(S) == 0) {return(dimen);} |
---|
1256 | for (i = 1; i <= sd; i++) {dimen = dimen +(n^i);} |
---|
1257 | for (i = 1; i <= nrows(S); i++) |
---|
1258 | {intvec St = S[i,1..ncols(S)]; |
---|
1259 | dimen = dimen + findDimen(St,n,L,P); |
---|
1260 | kill St; |
---|
1261 | } |
---|
1262 | return(dimen); |
---|
1263 | } |
---|
1264 | else |
---|
1265 | {for (i = 1; i <= size(P); i++) |
---|
1266 | {if (P[i] > degbound) {ERROR("degreebound is too small, GB contains elements of higher degree");}} |
---|
1267 | int sd; int dimen = 1; |
---|
1268 | intmat S; |
---|
1269 | sd = P[1]; |
---|
1270 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
1271 | sd = (sd - 1); |
---|
1272 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
1273 | else {S = createStartMat(sd,n);} |
---|
1274 | if (intvec(S) == 0) {return(dimen);} |
---|
1275 | for (i = 1; i <= sd; i++) {dimen = dimen +(n^i);} |
---|
1276 | for (i = 1; i <= nrows(S); i++) |
---|
1277 | {intvec St = S[i,1..ncols(S)]; |
---|
1278 | dimen = dimen + findDimen(St,n,L,P, degbound); |
---|
1279 | kill St; |
---|
1280 | } |
---|
1281 | return(dimen); |
---|
1282 | } |
---|
1283 | } |
---|
1284 | example |
---|
1285 | { |
---|
1286 | "EXAMPLE:"; echo = 2; |
---|
1287 | ring r = 0,(x,y),dp; |
---|
1288 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1289 | R; |
---|
1290 | setring R; // sets basering to Letterplace ring |
---|
1291 | //some intmats, which contain monomials in intvec representation as rows |
---|
1292 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
1293 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
1294 | print(I1); |
---|
1295 | print(I2); |
---|
1296 | print(J1); |
---|
1297 | print(J2); |
---|
1298 | list G = I1,I2; // ideal, which is already a Groebner basis |
---|
1299 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
1300 | ivKDim(G,2); // invokes the procedure without any degree bound |
---|
1301 | ivKDim(I,2,5); // invokes the procedure with degree bound 5 |
---|
1302 | } |
---|
1303 | |
---|
1304 | static proc ivMis2Base(list M) |
---|
1305 | "USAGE: ivMis2Base(M); M a list of intvecs |
---|
1306 | RETURN: ideal, a K-base of the given algebra |
---|
1307 | PURPOSE:Compute the K-base out of given mistletoes |
---|
1308 | ASSUME: - The mistletoes have to be ordered lexicographically -> OrdMisLex. |
---|
1309 | @* Otherwise there might some elements missing. |
---|
1310 | @* - basering is a Letterplace ring. |
---|
1311 | @* - mistletoes are stored as intvecs, as described in the overview |
---|
1312 | EXAMPLE: example ivMis2Base; shows examples |
---|
1313 | " |
---|
1314 | { |
---|
1315 | //checkAssumptions(0,M); |
---|
1316 | intvec L,A; |
---|
1317 | if (size(M) == 0){ERROR("There are no mistletoes, so it appears your dimension is infinite!");} |
---|
1318 | if (isInList(L,M) > 0) {print("1 is a mistletoe, therefore 1 is the only basis element"); return(list(intvec(0)));} |
---|
1319 | int i,j,d,s; |
---|
1320 | list Rt; |
---|
1321 | Rt[1] = intvec(0); |
---|
1322 | L = M[1]; |
---|
1323 | for (i = size(L); 1 <= i; i--) {Rt = insert(Rt,intvec(L[1..i]));} |
---|
1324 | for (i = 2; i <= size(M); i++) |
---|
1325 | {A = M[i]; L = M[i-1]; |
---|
1326 | s = size(A); |
---|
1327 | if (s > size(L)) |
---|
1328 | {d = size(L); |
---|
1329 | for (j = s; j > d; j--) {Rt = insert(Rt,intvec(A[1..j]));} |
---|
1330 | A = A[1..d]; |
---|
1331 | } |
---|
1332 | if (size(L) > s){L = L[1..s];} |
---|
1333 | while (A <> L) |
---|
1334 | {Rt = insert(Rt, intvec(A)); |
---|
1335 | if (size(A) > 1) |
---|
1336 | {A = A[1..(size(A)-1)]; |
---|
1337 | L = L[1..(size(L)-1)]; |
---|
1338 | } |
---|
1339 | else {break;} |
---|
1340 | } |
---|
1341 | } |
---|
1342 | return(Rt); |
---|
1343 | } |
---|
1344 | example |
---|
1345 | { |
---|
1346 | "EXAMPLE:"; echo = 2; |
---|
1347 | ring r = 0,(x,y),dp; |
---|
1348 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1349 | R; |
---|
1350 | setring R; // sets basering to Letterplace ring |
---|
1351 | intvec i1 = 1,2; intvec i2 = 2,1,2; |
---|
1352 | // the mistletoes are xy and yxy, which are already ordered lexicographically |
---|
1353 | list L = i1,i2; |
---|
1354 | ivMis2Base(L); // returns the basis of the factor algebra |
---|
1355 | } |
---|
1356 | |
---|
1357 | |
---|
1358 | static proc ivMis2Dim(list M) |
---|
1359 | "USAGE: ivMis2Dim(M); M a list of intvecs |
---|
1360 | RETURN: int, the K-dimension of the given algebra |
---|
1361 | PURPOSE:Compute the K-dimension out of given mistletoes |
---|
1362 | ASSUME: - The mistletoes have to be ordered lexicographically -> OrdMisLex. |
---|
1363 | @* Otherwise the returned value may differ from the K-dimension. |
---|
1364 | @* - basering is a Letterplace ring. |
---|
1365 | EXAMPLE: example ivMis2Dim; shows examples |
---|
1366 | " |
---|
1367 | {checkAssumptions(0,M); |
---|
1368 | intvec L; |
---|
1369 | if (size(M) == 0){ERROR("There are no mistletoes, so it appears your dimension is infinite!");} |
---|
1370 | if (isInList(L,M) > 0) {print("1 is a mistletoe, therefore dim = 1"); return(1);} |
---|
1371 | int i,j,d,s; |
---|
1372 | j = 1; |
---|
1373 | d = 1 + size(M[1]); |
---|
1374 | for (i = 1; i < size(M); i++) |
---|
1375 | {s = size(M[i]); if (s > size(M[i+1])){s = size(M[i+1]);} |
---|
1376 | while ((M[i][j] == M[i+1][j]) && (j <= s)){j = j + 1;} |
---|
1377 | d = d + size(M[i+1])- j + 1; |
---|
1378 | } |
---|
1379 | return(d); |
---|
1380 | } |
---|
1381 | example |
---|
1382 | { |
---|
1383 | "EXAMPLE:"; echo = 2; |
---|
1384 | ring r = 0,(x,y),dp; |
---|
1385 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1386 | R; |
---|
1387 | setring R; // sets basering to Letterplace ring |
---|
1388 | intvec i1 = 1,2; intvec i2 = 2,1,2; |
---|
1389 | // the mistletoes are xy and yxy, which are already ordered lexicographically |
---|
1390 | list L = i1,i2; |
---|
1391 | ivMis2Dim(L); // returns the dimension of the factor algebra |
---|
1392 | } |
---|
1393 | |
---|
1394 | static proc ivOrdMisLex(list M) |
---|
1395 | "USAGE: ivOrdMisLex(M); M a list of intvecs |
---|
1396 | RETURN: list, containing the ordered intvecs of M |
---|
1397 | PURPOSE:Orders a given set of mistletoes lexicographically |
---|
1398 | ASSUME: - basering is a Letterplace ring. |
---|
1399 | - intvecs correspond to monomials |
---|
1400 | NOTE: - This is preprocessing, it's not needed if the mistletoes are returned |
---|
1401 | @* from the sickle algorithm. |
---|
1402 | @* - Each entry of the list returned is an intvec. |
---|
1403 | EXAMPLE: example ivOrdMisLex; shows examples |
---|
1404 | " |
---|
1405 | {checkAssumptions(0,M); |
---|
1406 | return(sort(M)[1]); |
---|
1407 | } |
---|
1408 | example |
---|
1409 | { |
---|
1410 | "EXAMPLE:"; echo = 2; |
---|
1411 | ring r = 0,(x,y),dp; |
---|
1412 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1413 | setring R; // sets basering to Letterplace ring |
---|
1414 | intvec i1 = 1,2,1; intvec i2 = 2,2,1; intvec i3 = 1,1; intvec i4 = 2,1,1,1; |
---|
1415 | // the corresponding monomials are xyx,y^2x,x^2,yx^3 |
---|
1416 | list M = i1,i2,i3,i4; |
---|
1417 | M; |
---|
1418 | ivOrdMisLex(M);// orders the list of monomials |
---|
1419 | } |
---|
1420 | |
---|
1421 | static proc ivSickle(list L, int n, list #) |
---|
1422 | "USAGE: ivSickle(L,n,[degbound]); L a list of intmats, n an int, degbound an |
---|
1423 | @* optional integer |
---|
1424 | RETURN: list, containing intvecs, the mistletoes of A/<L> |
---|
1425 | PURPOSE:Compute the mistletoes for a given Groebner basis L |
---|
1426 | ASSUME: - basering is a Letterplace ring. |
---|
1427 | @* - all rows of each intmat correspond to a Letterplace monomial |
---|
1428 | @* - if you specify a different degree bound degbound, |
---|
1429 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
1430 | NOTE: - If degbound is set, a degree bound will be added. By default there |
---|
1431 | @* is no degree bound. |
---|
1432 | @* - n is the number of variables. |
---|
1433 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
1434 | EXAMPLE: example ivSickle; shows examples |
---|
1435 | " |
---|
1436 | {list M; |
---|
1437 | int degbound = 0; |
---|
1438 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] > 0){degbound = #[1];}}} |
---|
1439 | int i; |
---|
1440 | intvec P,H; |
---|
1441 | for (i = 1; i <= size(L); i++) |
---|
1442 | {P[i] = ncols(L[i]); |
---|
1443 | if (P[i] == 1) {if (isInMat(H,L[i]) > 0) {ERROR("Quotient algebra is trivial");}} |
---|
1444 | } |
---|
1445 | if (size(L) == 0) {ERROR("GB is empty, quotient algebra corresponds to free algebra");} |
---|
1446 | kill H; |
---|
1447 | checkAssumptions(degbound,L); |
---|
1448 | if (degbound == 0) |
---|
1449 | {intmat S; int sd; |
---|
1450 | sd = P[1]; |
---|
1451 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
1452 | sd = (sd - 1); |
---|
1453 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
1454 | else {S = createStartMat(sd,n);} |
---|
1455 | if (intvec(S) == 0) {return(list (intvec(0)));} |
---|
1456 | for (i = 1; i <= nrows(S); i++) |
---|
1457 | {intvec St = S[i,1..ncols(S)]; |
---|
1458 | M = M + findmistletoes(St,n,L,P); |
---|
1459 | kill St; |
---|
1460 | } |
---|
1461 | return(M); |
---|
1462 | } |
---|
1463 | else |
---|
1464 | {for (i = 1; i <= size(P); i++) |
---|
1465 | {if (P[i] > degbound) {ERROR("degreebound is too small, GB contains elements of higher degree");}} |
---|
1466 | intmat S; int sd; |
---|
1467 | sd = P[1]; |
---|
1468 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
1469 | sd = (sd - 1); |
---|
1470 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
1471 | else {S = createStartMat(sd,n);} |
---|
1472 | if (intvec(S) == 0) {return(list (intvec(0)));} |
---|
1473 | for (i = 1; i <= nrows(S); i++) |
---|
1474 | {intvec St = S[i,1..ncols(S)]; |
---|
1475 | M = M + findmistletoes(St,n,L,P,degbound); |
---|
1476 | kill St; |
---|
1477 | } |
---|
1478 | return(M); |
---|
1479 | } |
---|
1480 | } |
---|
1481 | example |
---|
1482 | { |
---|
1483 | "EXAMPLE:"; echo = 2; |
---|
1484 | ring r = 0,(x,y),dp; |
---|
1485 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1486 | setring R; // sets basering to Letterplace ring |
---|
1487 | //some intmats, which contain monomials in intvec representation as rows |
---|
1488 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
1489 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
1490 | print(I1); |
---|
1491 | print(I2); |
---|
1492 | print(J1); |
---|
1493 | print(J2); |
---|
1494 | list G = I1,I2; // ideal, which is already a Groebner basis |
---|
1495 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
1496 | ivSickle(G,2); // invokes the procedure without any degree bound |
---|
1497 | ivSickle(I,2,5); // invokes the procedure with degree bound 5 |
---|
1498 | } |
---|
1499 | |
---|
1500 | static proc ivSickleDim(list L, int n, list #) |
---|
1501 | "USAGE: ivSickleDim(L,n[,degbound]); L a list of intmats, n an integer, degbound |
---|
1502 | @* an optional integer |
---|
1503 | RETURN: list |
---|
1504 | PURPOSE:Compute mistletoes and the K-dimension |
---|
1505 | ASSUME: - basering is a Letterplace ring. |
---|
1506 | @* - all rows of each intmat correspond to a Letterplace monomial |
---|
1507 | @* - if you specify a different degree bound degbound, |
---|
1508 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
1509 | NOTE: - If L is the list returned, then L[1] is an integer, L[2] is a list, |
---|
1510 | @* containing the mistletoes as intvecs. |
---|
1511 | @* - If degbound is set, a degree bound will be added. By default there |
---|
1512 | @* is no degree bound. |
---|
1513 | @* - n is the number of variables. |
---|
1514 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
1515 | EXAMPLE: example ivSickleDim; shows examples |
---|
1516 | " |
---|
1517 | {list M; |
---|
1518 | int degbound = 0; |
---|
1519 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] > 0){degbound = #[1];}}} |
---|
1520 | int i,dimen; list R; |
---|
1521 | intvec P,H; |
---|
1522 | for (i = 1; i <= size(L); i++) |
---|
1523 | {P[i] = ncols(L[i]); |
---|
1524 | if (P[i] == 1) {if (isInMat(H,L[i]) > 0) {ERROR("Quotient algebra is trivial, dimension equals zero");}} |
---|
1525 | } |
---|
1526 | if (size(L) == 0) {ERROR("GB is empty, quotient algebra corresponds to free algebra");} |
---|
1527 | kill H; |
---|
1528 | checkAssumptions(degbound,L); |
---|
1529 | if (degbound == 0) |
---|
1530 | {int sd; dimen = 1; |
---|
1531 | intmat S; |
---|
1532 | sd = P[1]; |
---|
1533 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
1534 | sd = (sd - 1); |
---|
1535 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
1536 | else {S = createStartMat(sd,n);} |
---|
1537 | if (intvec(S) == 0) {return(list(dimen,list(intvec(0))));} |
---|
1538 | for (i = 1; i <= sd; i++) {dimen = dimen +(n^i);} |
---|
1539 | R[1] = dimen; |
---|
1540 | for (i = 1; i <= nrows(S); i++) |
---|
1541 | {intvec St = S[i,1..ncols(S)]; |
---|
1542 | R = findMisDim(St,n,L,P,R); |
---|
1543 | kill St; |
---|
1544 | } |
---|
1545 | return(R); |
---|
1546 | } |
---|
1547 | else |
---|
1548 | {for (i = 1; i <= size(P); i++) |
---|
1549 | {if (P[i] > degbound) {ERROR("degreebound is too small, GB contains elements of higher degree");}} |
---|
1550 | int sd; dimen = 1; |
---|
1551 | intmat S; |
---|
1552 | sd = P[1]; |
---|
1553 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
1554 | sd = (sd - 1); |
---|
1555 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
1556 | else {S = createStartMat(sd,n);} |
---|
1557 | if (intvec(S) == 0) {return(list(dimen,list(intvec(0))));} |
---|
1558 | for (i = 1; i <= sd; i++) {dimen = dimen +(n^i);} |
---|
1559 | R[1] = dimen; |
---|
1560 | for (i = 1; i <= nrows(S); i++) |
---|
1561 | {intvec St = S[i,1..ncols(S)]; |
---|
1562 | R = findMisDim(St,n,L,P,R,degbound); |
---|
1563 | kill St; |
---|
1564 | } |
---|
1565 | return(R); |
---|
1566 | } |
---|
1567 | } |
---|
1568 | example |
---|
1569 | { |
---|
1570 | "EXAMPLE:"; echo = 2; |
---|
1571 | ring r = 0,(x,y),dp; |
---|
1572 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1573 | setring R; // sets basering to Letterplace ring |
---|
1574 | //some intmats, which contain monomials in intvec representation as rows |
---|
1575 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
1576 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
1577 | print(I1); |
---|
1578 | print(I2); |
---|
1579 | print(J1); |
---|
1580 | print(J2); |
---|
1581 | list G = I1,I2;// ideal, which is already a Groebner basis |
---|
1582 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
1583 | ivSickleDim(G,2); // invokes the procedure without any degree bound |
---|
1584 | ivSickleDim(I,2,5); // invokes the procedure with degree bound 5 |
---|
1585 | } |
---|
1586 | |
---|
1587 | static proc ivSickleHil(list L, int n, list #) |
---|
1588 | "USAGE:ivSickleHil(L,n[,degbound]); L a list of intmats, n an integer, |
---|
1589 | @* degbound an optional integer |
---|
1590 | RETURN: list |
---|
1591 | PURPOSE:Compute the mistletoes and the Hilbert series |
---|
1592 | ASSUME: - basering is a Letterplace ring. |
---|
1593 | @* - all rows of each intmat correspond to a Letterplace monomial |
---|
1594 | @* - if you specify a different degree bound degbound, |
---|
1595 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
1596 | NOTE: - If L is the list returned, then L[1] is an intvec, L[2] is a list, |
---|
1597 | @* containing the mistletoes as intvecs. |
---|
1598 | @* - If degbound is set, a degree bound will be added. By default there |
---|
1599 | @* is no degree bound. |
---|
1600 | @* - n is the number of variables. |
---|
1601 | @* - If I = L[1] is the intvec returned, then I[k] is the (k-1)-th |
---|
1602 | @* coefficient of the Hilbert series. |
---|
1603 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
1604 | EXAMPLE: example ivSickleHil; shows examples |
---|
1605 | " |
---|
1606 | {int degbound = 0; |
---|
1607 | if (size(#) > 0) {if (typeof(#[1])=="int"){if (#[1] > 0) {degbound = #[1];}}} |
---|
1608 | intvec P,H; int i; list R; |
---|
1609 | for (i = 1; i <= size(L); i++) |
---|
1610 | {P[i] = ncols(L[i]); |
---|
1611 | if (P[i] == 1) {if ( isInMat(H,L[i]) > 0) {ERROR("Quotient algebra is trivial");}} |
---|
1612 | } |
---|
1613 | if (size(L) == 0) {ERROR("GB is empty, quotient algebra corresponds to free algebra");} |
---|
1614 | H[1] = 1; |
---|
1615 | checkAssumptions(degbound,L); |
---|
1616 | if (degbound == 0) |
---|
1617 | {int sd; |
---|
1618 | intmat S; |
---|
1619 | sd = P[1]; |
---|
1620 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
1621 | sd = (sd - 1); |
---|
1622 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
1623 | else {S = createStartMat(sd,n);} |
---|
1624 | if (intvec(S) == 0) {return(list(H,list(intvec (0))));} |
---|
1625 | for (i = 1; i <= sd; i++) {H = H,(n^i);} |
---|
1626 | R[1] = H; kill H; |
---|
1627 | for (i = 1; i <= nrows(S); i++) |
---|
1628 | {intvec St = S[i,1..ncols(S)]; |
---|
1629 | R = findHCoeffMis(St,n,L,P,R); |
---|
1630 | kill St; |
---|
1631 | } |
---|
1632 | return(R); |
---|
1633 | } |
---|
1634 | else |
---|
1635 | {for (i = 1; i <= size(P); i++) |
---|
1636 | {if (P[i] > degbound) {ERROR("degreebound is too small, GB contains elements of higher degree");}} |
---|
1637 | int sd; |
---|
1638 | intmat S; |
---|
1639 | sd = P[1]; |
---|
1640 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
1641 | sd = (sd - 1); |
---|
1642 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
1643 | else {S = createStartMat(sd,n);} |
---|
1644 | if (intvec(S) == 0) {return(list(H,list(intvec(0))));} |
---|
1645 | for (i = 1; i <= sd; i++) {H = H,(n^i);} |
---|
1646 | R[1] = H; kill H; |
---|
1647 | for (i = 1; i <= nrows(S); i++) |
---|
1648 | {intvec St = S[i,1..ncols(S)]; |
---|
1649 | R = findHCoeffMis(St,n,L,P,R,degbound); |
---|
1650 | kill St; |
---|
1651 | } |
---|
1652 | return(R); |
---|
1653 | } |
---|
1654 | } |
---|
1655 | example |
---|
1656 | { |
---|
1657 | "EXAMPLE:"; echo = 2; |
---|
1658 | ring r = 0,(x,y),dp; |
---|
1659 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1660 | setring R; // sets basering to Letterplace ring |
---|
1661 | //some intmats, which contain monomials in intvec representation as rows |
---|
1662 | intmat I1[2][2] = 1,1,2,2; intmat I2[1][3] = 1,2,1; |
---|
1663 | intmat J1[1][2] = 1,1; intmat J2[2][3] = 2,1,2,1,2,1; |
---|
1664 | print(I1); |
---|
1665 | print(I2); |
---|
1666 | print(J1); |
---|
1667 | print(J2); |
---|
1668 | list G = I1,I2;// ideal, which is already a Groebner basis |
---|
1669 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
1670 | ivSickleHil(G,2); // invokes the procedure without any degree bound |
---|
1671 | ivSickleHil(I,2,5); // invokes the procedure with degree bound 5 |
---|
1672 | } |
---|
1673 | |
---|
1674 | static proc lpDHilbert(ideal G, list #) |
---|
1675 | "USAGE: lpDHilbert(G[,degbound,n]); G an ideal, degbound, n optional integers |
---|
1676 | RETURN: list |
---|
1677 | PURPOSE:Compute K-dimension and Hilbert series, starting with a lp-ideal |
---|
1678 | ASSUME: - basering is a Letterplace ring. |
---|
1679 | @* - if you specify a different degree bound degbound, |
---|
1680 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
1681 | NOTE: - If L is the list returned, then L[1] is an integer corresponding to the |
---|
1682 | @* dimension, L[2] is an intvec which contains the coefficients of the |
---|
1683 | @* Hilbert series |
---|
1684 | @* - If degbound is set, there will be a degree bound added. 0 means no |
---|
1685 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
1686 | @* - n can be set to a different number of variables. |
---|
1687 | @* Default: n = attrib(basering, lV). |
---|
1688 | @* - If I = L[2] is the intvec returned, then I[k] is the (k-1)-th |
---|
1689 | @* coefficient of the Hilbert series. |
---|
1690 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
1691 | EXAMPLE: example lpDHilbert; shows examples |
---|
1692 | " |
---|
1693 | {int degbound = lpDegBound(basering);int n = lpVarBlockSize(basering); |
---|
1694 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
1695 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
1696 | list L; |
---|
1697 | L = lp2ivId(normalize(lead(G))); |
---|
1698 | return(ivDHilbert(L,n,degbound)); |
---|
1699 | } |
---|
1700 | example |
---|
1701 | { |
---|
1702 | "EXAMPLE:"; echo = 2; |
---|
1703 | ring r = 0,(x,y),dp; |
---|
1704 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1705 | setring R; // sets basering to Letterplace ring |
---|
1706 | ideal G = x*x, y*y,x*y*x; // ideal G contains a |
---|
1707 | //Groebner basis |
---|
1708 | lpDHilbert(G,5,2); // invokes procedure with degree bound 5 and 2 variables |
---|
1709 | // note that the optional parameters are not necessary, due to the finiteness |
---|
1710 | // of the K-dimension of the factor algebra |
---|
1711 | lpDHilbert(G); // procedure with ring parameters |
---|
1712 | lpDHilbert(G,0); // procedure without degreebound |
---|
1713 | } |
---|
1714 | |
---|
1715 | static proc lpDHilbertSickle(ideal G, list #) |
---|
1716 | "USAGE: lpDHilbertSickle(G[,degbound,n]); G an ideal, degbound, n optional |
---|
1717 | @* integers |
---|
1718 | RETURN: list |
---|
1719 | PURPOSE:Compute K-dimension, Hilbert series and mistletoes at once |
---|
1720 | ASSUME: - basering is a Letterplace ring. |
---|
1721 | @* - if you specify a different degree bound degbound, |
---|
1722 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
1723 | NOTE: - If L is the list returned, then L[1] is an integer, the K-dimension, |
---|
1724 | @* L[2] is an intvec, the Hilbert series and L[3] is an ideal, |
---|
1725 | @* the mistletoes |
---|
1726 | @* - If degbound is set, there will be a degree bound added. 0 means no |
---|
1727 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
1728 | @* - n can be set to a different number of variables. |
---|
1729 | @* Default: n = attrib(basering, lV). |
---|
1730 | @* - If I = L[1] is the intvec returned, then I[k] is the (k-1)-th |
---|
1731 | @* coefficient of the Hilbert series. |
---|
1732 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
1733 | EXAMPLE: example lpDHilbertSickle; shows examples |
---|
1734 | " |
---|
1735 | {int degbound = lpDegBound(basering);int n = lpVarBlockSize(basering); |
---|
1736 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
1737 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
1738 | list L; |
---|
1739 | L = lp2ivId(normalize(lead(G))); |
---|
1740 | L = ivDHilbertSickle(L,n,degbound); |
---|
1741 | L[3] = ivL2lpI(L[3]); |
---|
1742 | return(L); |
---|
1743 | } |
---|
1744 | example |
---|
1745 | { |
---|
1746 | "EXAMPLE:"; echo = 2; |
---|
1747 | ring r = 0,(x,y),dp; |
---|
1748 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1749 | setring R; // sets basering to Letterplace ring |
---|
1750 | ideal G = x*x, y*y,x*y*x; // ideal G contains a |
---|
1751 | //Groebner basis |
---|
1752 | lpDHilbertSickle(G,5,2); //invokes procedure with degree bound 5 and 2 variables |
---|
1753 | // note that the optional parameters are not necessary, due to the finiteness |
---|
1754 | // of the K-dimension of the factor algebra |
---|
1755 | lpDHilbertSickle(G); // procedure with ring parameters |
---|
1756 | lpDHilbertSickle(G,0); // procedure without degreebound |
---|
1757 | } |
---|
1758 | |
---|
1759 | proc lpHilbert(ideal G, list #) |
---|
1760 | "USAGE: lpHilbert(G[,degbound,n]); G an ideal, degbound, n optional integers |
---|
1761 | RETURN: intvec, containing the coefficients of the Hilbert series |
---|
1762 | PURPOSE: Compute the truncated Hilbert series of K<X>/<G> up to a degree bound |
---|
1763 | ASSUME: - basering is a Letterplace ring. |
---|
1764 | @* - if you specify a different degree bound degbound, |
---|
1765 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
1766 | THEORY: Hilbert series of an algebra K<X>/<G> is sum_(i>=0) h_i t^i, |
---|
1767 | where h_i is the K-dimension of the space of monomials of degree i, |
---|
1768 | not contained in <G>. For finitely presented algebras Hilbert series NEED |
---|
1769 | NOT be a rational function, though it happens often. Therefore in general |
---|
1770 | there is no notion of a Hilbert polynomial. |
---|
1771 | NOTE: - If degbound is set, there will be a degree bound added. 0 means no |
---|
1772 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
1773 | @* - n is the number of variables, which can be set to a different number. |
---|
1774 | @* Default: attrib(basering, lV). |
---|
1775 | @* - In the output intvec I, I[k] is the (k-1)-th coefficient of the Hilbert |
---|
1776 | @* series, i.e. h_(k-1) as above. |
---|
1777 | EXAMPLE: example lpHilbert; shows examples |
---|
1778 | SEE ALSO: ncHilb_lib |
---|
1779 | " |
---|
1780 | {int degbound = lpDegBound(basering);int n = lpVarBlockSize(basering); |
---|
1781 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
1782 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
1783 | list L; |
---|
1784 | L = lp2ivId(normalize(lead(G))); |
---|
1785 | return(ivHilbert(L,n,degbound)); |
---|
1786 | } |
---|
1787 | example |
---|
1788 | { |
---|
1789 | "EXAMPLE:"; echo = 2; |
---|
1790 | ring r = 0,(x,y),dp; |
---|
1791 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1792 | setring R; // sets basering to Letterplace ring |
---|
1793 | ideal G = y*y,x*y*x; // G is a Groebner basis |
---|
1794 | lpHilbert(G); // procedure with default parameters |
---|
1795 | lpHilbert(G,3,2); // invokes procedure with degree bound 3 and (same) 2 variables |
---|
1796 | } |
---|
1797 | |
---|
1798 | // compatibiltiy, do not put in header |
---|
1799 | proc lpDimCheck(ideal G) |
---|
1800 | { |
---|
1801 | return(lpKDimCheck(G)); |
---|
1802 | } |
---|
1803 | |
---|
1804 | proc lpKDimCheck(ideal G) |
---|
1805 | "USAGE: lpKDimCheck(G); |
---|
1806 | RETURN: int, 1 if K-dimension of the factor algebra is infinite, 0 otherwise |
---|
1807 | PURPOSE:Checking a factor algebra for finiteness of the K-dimension |
---|
1808 | ASSUME: - basering is a Letterplace ring. |
---|
1809 | EXAMPLE: example lpKDimCheck; shows examples |
---|
1810 | " |
---|
1811 | {int n = lpVarBlockSize(basering); |
---|
1812 | list L; |
---|
1813 | ideal R; |
---|
1814 | R = normalize(lead(G)); |
---|
1815 | L = lp2ivId(R); |
---|
1816 | return(ivKDimCheck(L,n)); |
---|
1817 | } |
---|
1818 | example |
---|
1819 | { |
---|
1820 | "EXAMPLE:"; echo = 2; |
---|
1821 | ring r = 0,(x,y),dp; |
---|
1822 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1823 | setring R; // sets basering to Letterplace ring |
---|
1824 | ideal G = x*x, y*y,x*y*x; |
---|
1825 | // Groebner basis |
---|
1826 | ideal I = x*x, y*x*y, x*y*x; |
---|
1827 | // Groebner basis |
---|
1828 | lpKDimCheck(G); // invokes procedure, factor algebra is of finite K-dimension |
---|
1829 | lpKDimCheck(I); // invokes procedure, factor algebra is of infinite Kdimension |
---|
1830 | } |
---|
1831 | |
---|
1832 | proc lpKDim(ideal G, list #) |
---|
1833 | "USAGE: lpKDim(G[,degbound, n]); G an ideal, degbound, n optional integers |
---|
1834 | RETURN: int, the K-dimension of the factor algebra |
---|
1835 | PURPOSE:Compute the K-dimension of a factor algebra, given via an ideal |
---|
1836 | ASSUME: - basering is a Letterplace ring |
---|
1837 | @* - if you specify a different degree bound degbound, |
---|
1838 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
1839 | NOTE: - If degbound is set, there will be a degree bound added. 0 means no |
---|
1840 | @* degree bound. Default: attrib(basering, uptodeg). |
---|
1841 | @* - n is the number of variables, which can be set to a different number. |
---|
1842 | @* Default: attrib(basering, lV). |
---|
1843 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
1844 | EXAMPLE: example lpKDim; shows examples |
---|
1845 | " |
---|
1846 | {int degbound = lpDegBound(basering);int n = lpVarBlockSize(basering); |
---|
1847 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
1848 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
1849 | list L; |
---|
1850 | L = lp2ivId(normalize(lead(G))); |
---|
1851 | return(ivKDim(L,n,degbound)); |
---|
1852 | } |
---|
1853 | example |
---|
1854 | { |
---|
1855 | "EXAMPLE:"; echo = 2; |
---|
1856 | ring r = 0,(x,y),dp; |
---|
1857 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1858 | setring R; // sets basering to Letterplace ring |
---|
1859 | ideal G = x*x, y*y,x*y*x; |
---|
1860 | // ideal G contains a Groebner basis |
---|
1861 | lpKDim(G); //procedure invoked with ring parameters |
---|
1862 | // the factor algebra is finite, so the degree bound given by the Letterplace |
---|
1863 | // ring is not necessary |
---|
1864 | lpKDim(G,0); // procedure without any degree bound |
---|
1865 | } |
---|
1866 | |
---|
1867 | static proc lpMis2Base(ideal M) |
---|
1868 | "USAGE: lpMis2Base(M); M an ideal |
---|
1869 | RETURN: ideal, a K-basis of the factor algebra |
---|
1870 | PURPOSE:Compute a K-basis out of given mistletoes |
---|
1871 | ASSUME: - basering is a Letterplace ring. G is a Letterplace ideal. |
---|
1872 | @* - M contains only monomials |
---|
1873 | NOTE: - The mistletoes have to be ordered lexicographically -> OrdMisLex. |
---|
1874 | EXAMPLE: example lpMis2Base; shows examples |
---|
1875 | " |
---|
1876 | {list L; |
---|
1877 | L = lpId2ivLi(M); |
---|
1878 | return(ivL2lpI(ivMis2Base(L))); |
---|
1879 | } |
---|
1880 | example |
---|
1881 | { |
---|
1882 | "EXAMPLE:"; echo = 2; |
---|
1883 | ring r = 0,(x,y),dp; |
---|
1884 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1885 | setring R; // sets basering to Letterplace ring |
---|
1886 | ideal L = x*y,y*x*y; |
---|
1887 | // ideal containing the mistletoes |
---|
1888 | lpMis2Base(L); // returns the K-basis of the factor algebra |
---|
1889 | } |
---|
1890 | |
---|
1891 | static proc lpMis2Dim(ideal M) |
---|
1892 | "USAGE: lpMis2Dim(M); M an ideal |
---|
1893 | RETURN: int, the K-dimension of the factor algebra |
---|
1894 | PURPOSE:Compute the K-dimension out of given mistletoes |
---|
1895 | ASSUME: - basering is a Letterplace ring. |
---|
1896 | @* - M contains only monomials |
---|
1897 | NOTE: - The mistletoes have to be ordered lexicographically -> OrdMisLex. |
---|
1898 | EXAMPLE: example lpMis2Dim; shows examples |
---|
1899 | " |
---|
1900 | {list L; |
---|
1901 | L = lpId2ivLi(M); |
---|
1902 | return(ivMis2Dim(L)); |
---|
1903 | } |
---|
1904 | example |
---|
1905 | { |
---|
1906 | "EXAMPLE:"; echo = 2; |
---|
1907 | ring r = 0,(x,y),dp; |
---|
1908 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1909 | setring R; // sets basering to Letterplace ring |
---|
1910 | ideal L = x*y,y*x*y; |
---|
1911 | // ideal containing the mistletoes |
---|
1912 | lpMis2Dim(L); // returns the K-dimension of the factor algebra |
---|
1913 | } |
---|
1914 | |
---|
1915 | static proc lpOrdMisLex(ideal M) |
---|
1916 | "USAGE: lpOrdMisLex(M); M an ideal of mistletoes |
---|
1917 | RETURN: ideal, containing the mistletoes, ordered lexicographically |
---|
1918 | PURPOSE:A given set of mistletoes is ordered lexicographically |
---|
1919 | ASSUME: - basering is a Letterplace ring. |
---|
1920 | NOTE: This is preprocessing, it is not needed if the mistletoes are returned |
---|
1921 | @* from the sickle algorithm. |
---|
1922 | EXAMPLE: example lpOrdMisLex; shows examples |
---|
1923 | " |
---|
1924 | {return(ivL2lpI(sort(lpId2ivLi(M))[1]));} |
---|
1925 | example |
---|
1926 | { |
---|
1927 | "EXAMPLE:"; echo = 2; |
---|
1928 | ring r = 0,(x,y),dp; |
---|
1929 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1930 | setring R; // sets basering to Letterplace ring |
---|
1931 | ideal M = x*y*x, y*y*x, x*x, y*x*x*x; |
---|
1932 | // some monomials |
---|
1933 | lpOrdMisLex(M); // orders the monomials lexicographically |
---|
1934 | } |
---|
1935 | |
---|
1936 | static proc lpSickle(ideal G, list #) |
---|
1937 | "USAGE: lpSickle(G[,degbound,n]); G an ideal, degbound, n optional integers |
---|
1938 | RETURN: ideal |
---|
1939 | PURPOSE:Compute the mistletoes of K[X]/<G> |
---|
1940 | ASSUME: - basering is a Letterplace ring. |
---|
1941 | @* - if you specify a different degree bound degbound, |
---|
1942 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
1943 | NOTE: - If degbound is set, there will be a degree bound added. 0 means no |
---|
1944 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
1945 | @* - n is the number of variables, which can be set to a different number. |
---|
1946 | @* Default: attrib(basering, lV). |
---|
1947 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
1948 | EXAMPLE: example lpSickle; shows examples |
---|
1949 | " |
---|
1950 | {int degbound = lpDegBound(basering); int n = lpVarBlockSize(basering); |
---|
1951 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
1952 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
1953 | list L; ideal R; |
---|
1954 | R = normalize(lead(G)); |
---|
1955 | L = lp2ivId(R); |
---|
1956 | L = ivSickle(L,n,degbound); |
---|
1957 | R = ivL2lpI(L); |
---|
1958 | return(R); |
---|
1959 | } |
---|
1960 | example |
---|
1961 | { |
---|
1962 | "EXAMPLE:"; echo = 2; |
---|
1963 | ring r = 0,(x,y),dp; |
---|
1964 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
1965 | setring R; // sets basering to Letterplace ring |
---|
1966 | ideal G = x*x, y*y,x*y*x; // ideal G contains a |
---|
1967 | //Groebner basis |
---|
1968 | lpSickle(G); //invokes the procedure with ring parameters |
---|
1969 | // the factor algebra is finite, so the degree bound given by the Letterplace |
---|
1970 | // ring is not necessary |
---|
1971 | lpSickle(G,0); // procedure without any degree bound |
---|
1972 | } |
---|
1973 | |
---|
1974 | proc lpSickleDim(ideal G, list #) |
---|
1975 | "USAGE: lpSickleDim(G[,degbound,n]); G an ideal, degbound, n optional integers |
---|
1976 | RETURN: list |
---|
1977 | PURPOSE:Compute the K-dimension and the mistletoes of K<X>/<G> |
---|
1978 | ASSUME: - basering is a Letterplace ring. |
---|
1979 | @* - if you specify a different degree bound degbound, |
---|
1980 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
1981 | NOTE: - If L is the list returned, then L[1] is an integer, the K-dimension, |
---|
1982 | @* L[2] is an ideal, the mistletoes. |
---|
1983 | @* - If degbound is set, there will be a degree bound added. 0 means no |
---|
1984 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
1985 | @* - n is the number of variables, which can be set to a different number. |
---|
1986 | @* Default: attrib(basering, lV). |
---|
1987 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
1988 | EXAMPLE: example lpSickleDim; shows examples |
---|
1989 | " |
---|
1990 | {int degbound = lpDegBound(basering);int n = lpVarBlockSize(basering); |
---|
1991 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
1992 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
1993 | list L; |
---|
1994 | L = lp2ivId(normalize(lead(G))); |
---|
1995 | L = ivSickleDim(L,n,degbound); |
---|
1996 | L[2] = ivL2lpI(L[2]); |
---|
1997 | return(L); |
---|
1998 | } |
---|
1999 | example |
---|
2000 | { |
---|
2001 | "EXAMPLE:"; echo = 2; |
---|
2002 | ring r = 0,(x,y),dp; |
---|
2003 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
2004 | setring R; // sets basering to Letterplace ring |
---|
2005 | ideal G = x*x, y*y,x*y*x; // G is a monomial Groebner basis |
---|
2006 | lpSickleDim(G); // invokes the procedure with ring parameters |
---|
2007 | // the factor algebra is finite, so the degree bound, given |
---|
2008 | // by the Letterplace ring is not necessary |
---|
2009 | lpSickleDim(G,0); // procedure without any degree bound |
---|
2010 | } |
---|
2011 | |
---|
2012 | static proc lpSickleHil(ideal G, list #) |
---|
2013 | "USAGE: lpSickleHil(G); |
---|
2014 | RETURN: list |
---|
2015 | PURPOSE:Compute the Hilbert series and the mistletoes |
---|
2016 | ASSUME: - basering is a Letterplace ring. |
---|
2017 | @* - if you specify a different degree bound degbound, |
---|
2018 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
2019 | NOTE: - If L is the list returned, then L[1] is an intvec, corresponding to the |
---|
2020 | @* Hilbert series, L[2] is an ideal, the mistletoes. |
---|
2021 | @* - If degbound is set, there will be a degree bound added. 0 means no |
---|
2022 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
2023 | @* - n is the number of variables, which can be set to a different number. |
---|
2024 | @* Default: attrib(basering, lV). |
---|
2025 | @* - If I = L[1] is the intvec returned, then I[k] is the (k-1)-th |
---|
2026 | @* coefficient of the Hilbert series. |
---|
2027 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
2028 | EXAMPLE: example lpSickleHil; shows examples |
---|
2029 | " |
---|
2030 | {int degbound = lpDegBound(basering);int n = lpVarBlockSize(basering); |
---|
2031 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
2032 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
2033 | list L; |
---|
2034 | L = lp2ivId(normalize(lead(G))); |
---|
2035 | L = ivSickleHil(L,n,degbound); |
---|
2036 | L[2] = ivL2lpI(L[2]); |
---|
2037 | return(L); |
---|
2038 | } |
---|
2039 | example |
---|
2040 | { |
---|
2041 | "EXAMPLE:"; echo = 2; |
---|
2042 | ring r = 0,(x,y),dp; |
---|
2043 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
2044 | setring R; // sets basering to Letterplace ring |
---|
2045 | ideal G = x*x, y*y,x*y*x; // ideal G contains a |
---|
2046 | //Groebner basis |
---|
2047 | lpSickleHil(G); // invokes the procedure with ring parameters |
---|
2048 | // the factor algebra is finite, so the degree bound given by the Letterplace |
---|
2049 | // ring is not necessary |
---|
2050 | lpSickleHil(G,0); // procedure without any degree bound |
---|
2051 | } |
---|
2052 | |
---|
2053 | static proc sickle(ideal G, list #) |
---|
2054 | "USAGE: sickle(G[,m, d, h, degbound]); G an ideal; m,d,h,degbound optional |
---|
2055 | @* integers |
---|
2056 | RETURN: list |
---|
2057 | PURPOSE:Allowing the user to access all procs with one command |
---|
2058 | ASSUME: - basering is a Letterplace ring. |
---|
2059 | @* - if you specify a different degree bound degbound, |
---|
2060 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
2061 | NOTE: The returned object will always be a list, but the entries of the |
---|
2062 | @* returned list may be very different |
---|
2063 | @* case m=1,d=1,h=1: see lpDHilbertSickle |
---|
2064 | @* case m=1,d=1,h=0: see lpSickleDim |
---|
2065 | @* case m=1,d=0,h=1: see lpSickleHil |
---|
2066 | @* case m=1,d=0,h=0: see lpSickle (this is the default case) |
---|
2067 | @* case m=0,d=1,h=1: see lpDHilbert |
---|
2068 | @* case m=0,d=1,h=0: see lpKDim |
---|
2069 | @* case m=0,d=0,h=1: see lpHilbert |
---|
2070 | @* case m=0,d=0,h=0: returns an error |
---|
2071 | @* - If degbound is set, there will be a degree bound added. 0 means no |
---|
2072 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
2073 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
2074 | EXAMPLE: example sickle; shows examples |
---|
2075 | " |
---|
2076 | {int m,d,h,degbound; |
---|
2077 | m = 1; d = 0; h = 0; degbound = lpDegBound(basering); |
---|
2078 | if (size(#) > 0) {if (typeof(#[1])=="int"){if (#[1] < 1) {m = 0;}}} |
---|
2079 | if (size(#) > 1) {if (typeof(#[1])=="int"){if (#[2] > 0) {d = 1;}}} |
---|
2080 | if (size(#) > 2) {if (typeof(#[1])=="int"){if (#[3] > 0) {h = 1;}}} |
---|
2081 | if (size(#) > 3) {if (typeof(#[1])=="int"){if (#[4] >= 0) {degbound = #[4];}}} |
---|
2082 | if (m == 1) |
---|
2083 | {if (d == 0) |
---|
2084 | {if (h == 0) {return(lpSickle(G,degbound,lpVarBlockSize(basering)));} |
---|
2085 | else {return(lpSickleHil(G,degbound,lpVarBlockSize(basering)));} |
---|
2086 | } |
---|
2087 | else |
---|
2088 | {if (h == 0) {return(lpSickleDim(G,degbound,lpVarBlockSize(basering)));} |
---|
2089 | else {return(lpDHilbertSickle(G,degbound,lpVarBlockSize(basering)));} |
---|
2090 | } |
---|
2091 | } |
---|
2092 | else |
---|
2093 | {if (d == 0) |
---|
2094 | {if (h == 0) {ERROR("You request to do nothing, so relax and do so");} |
---|
2095 | else {return(lpHilbert(G,degbound,lpVarBlockSize(basering)));} |
---|
2096 | } |
---|
2097 | else |
---|
2098 | {if (h == 0) {return(lpKDim(G,degbound,lpVarBlockSize(basering)));} |
---|
2099 | else {return(lpDHilbert(G,degbound,lpVarBlockSize(basering)));} |
---|
2100 | } |
---|
2101 | } |
---|
2102 | } |
---|
2103 | example |
---|
2104 | { |
---|
2105 | "EXAMPLE:"; echo = 2; |
---|
2106 | ring r = 0,(x,y),dp; |
---|
2107 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
2108 | setring R; // sets basering to Letterplace ring |
---|
2109 | ideal G = x*x, y*y,x*y*x; |
---|
2110 | // G contains a Groebner basis |
---|
2111 | sickle(G,1,1,1); // computes mistletoes, K-dimension and the Hilbert series |
---|
2112 | sickle(G,1,0,0); // computes mistletoes only |
---|
2113 | sickle(G,0,1,0); // computes K-dimension only |
---|
2114 | sickle(G,0,0,1); // computes Hilbert series only |
---|
2115 | } |
---|
2116 | |
---|
2117 | proc lpMonomialBasis(int d, int donly, ideal J) |
---|
2118 | "USAGE: lpMonomialBasis(d, donly, J); d, donly integers, J an ideal |
---|
2119 | RETURN: ideal |
---|
2120 | PURPOSE: computes a list of free monomials in a Letterplace |
---|
2121 | @* basering R of degree at most d and not contained in <LM(J)> |
---|
2122 | @* if donly <> 0, only monomials of degree d are returned |
---|
2123 | ASSUME: - basering is a Letterplace ring. |
---|
2124 | @* - d <= attrib(basering,uptodeg) holds. |
---|
2125 | @* - J is a Groebner basis |
---|
2126 | NOTE: will be replaced with reduce(maxideal(d), J); soon |
---|
2127 | " |
---|
2128 | { |
---|
2129 | if (d < 0) { |
---|
2130 | return (delete(ideal(0), 1)); // no monomials |
---|
2131 | } |
---|
2132 | ideal I = maxideal(d); |
---|
2133 | if (!donly) { |
---|
2134 | for (int i = d-1; i >= 0; i--) { |
---|
2135 | I = maxideal(i), I; |
---|
2136 | } kill i; |
---|
2137 | } |
---|
2138 | for (int i = ncols(I); i >= 1; i--) { |
---|
2139 | if (lpLmDivides(J, I[i])) { |
---|
2140 | I = delete(I, i); |
---|
2141 | } |
---|
2142 | } kill i; |
---|
2143 | return (I); |
---|
2144 | } |
---|
2145 | example |
---|
2146 | { |
---|
2147 | "EXAMPLE:"; echo = 2; |
---|
2148 | ring r = 0,(x,y),dp; |
---|
2149 | def R = freeAlgebra(r, 7); setring R; |
---|
2150 | ideal J = x*y*x - y*x*y; |
---|
2151 | option(redSB); option(redTail); |
---|
2152 | J = letplaceGBasis(J); |
---|
2153 | J; |
---|
2154 | //monomials of degree 2 only in K<x,y>: |
---|
2155 | lpMonomialBasis(2,1,ideal(0)); |
---|
2156 | //monomials of degree <=2 in K<x,y> |
---|
2157 | lpMonomialBasis(2,0,ideal(0)); |
---|
2158 | //monomials of degree 3 only in K<x,y>/J |
---|
2159 | lpMonomialBasis(3,1,J); |
---|
2160 | //monomials of degree <=3 in K<x,y>/J |
---|
2161 | lpMonomialBasis(3,0,J); |
---|
2162 | } |
---|
2163 | |
---|
2164 | /////////////////////////////////////////////////////////////////////////////// |
---|
2165 | |
---|
2166 | /* |
---|
2167 | Here are some examples one may try. Just copy them into your console. |
---|
2168 | These are relations for braid groups, up to degree d: |
---|
2169 | |
---|
2170 | LIB "fpadim.lib"; |
---|
2171 | ring r = 0,(x,y,z),dp; |
---|
2172 | int d =10; // degree |
---|
2173 | def R = freeAlgebra(r, d); |
---|
2174 | setring R; |
---|
2175 | ideal I = y*x*y - z*y*z, x*y*x - z*x*y, |
---|
2176 | z*x*z - y*z*x, x*x*x + y*y*y + |
---|
2177 | z*z*z + x*y*z; |
---|
2178 | option(prot); |
---|
2179 | option(redSB);option(redTail);option(mem); |
---|
2180 | ideal J = system("freegb",I,d,3); |
---|
2181 | lpKDimCheck(J); |
---|
2182 | sickle(J,1,1,1,d);//Computes mistletoes, K-dimension and the Hilbert series |
---|
2183 | |
---|
2184 | |
---|
2185 | |
---|
2186 | LIB "fpadim.lib"; |
---|
2187 | ring r = 0,(x,y,z),dp; |
---|
2188 | int d =11; // degree |
---|
2189 | def R = freeAlgebra(r, d); |
---|
2190 | setring R; |
---|
2191 | ideal I = y*x*y - z*y*z, x*y*z - z*x*y, |
---|
2192 | z*x*z - y*z*x, x*x*x + y*y*y + |
---|
2193 | z*z*z + x*y*z; |
---|
2194 | option(prot); |
---|
2195 | option(redSB);option(redTail);option(mem); |
---|
2196 | ideal J = system("freegb",I,d,3); |
---|
2197 | lpKDimCheck(J); |
---|
2198 | sickle(J,1,1,1,d); |
---|
2199 | |
---|
2200 | |
---|
2201 | |
---|
2202 | LIB "fpadim.lib"; |
---|
2203 | ring r = 0,(x,y,z),dp; |
---|
2204 | int d = 6; // degree |
---|
2205 | def R = freeAlgebra(r, d); |
---|
2206 | setring R; |
---|
2207 | ideal I = y*x*y - z*y*z, x*y*x - z*x*y, |
---|
2208 | z*x*z - y*z*x, x*x*x -2*y*y*y + 3*z*z*z -4*x*y*z + 5*x*z*z- 6*x*y*y +7*x*x*z - 8*x*x*y; |
---|
2209 | option(prot); |
---|
2210 | option(redSB);option(redTail);option(mem); |
---|
2211 | ideal J = system("freegb",I,d,3); |
---|
2212 | lpKDimCheck(J); |
---|
2213 | sickle(J,1,1,1,d); |
---|
2214 | */ |
---|
2215 | |
---|
2216 | /* |
---|
2217 | Here are some examples, which can also be found in [studzins]: |
---|
2218 | |
---|
2219 | // takes up to 880Mb of memory |
---|
2220 | LIB "fpadim.lib"; |
---|
2221 | ring r = 0,(x,y,z),dp; |
---|
2222 | int d =10; // degree |
---|
2223 | def R = freeAlgebra(r, d); |
---|
2224 | setring R; |
---|
2225 | ideal I = |
---|
2226 | z*z*z*z + y*x*y*x - x*y*y*x - 3*z*y*x*z, x*x*x + y*x*y - x*y*x, z*y*x-x*y*z + z*x*z; |
---|
2227 | option(prot); |
---|
2228 | option(redSB);option(redTail);option(mem); |
---|
2229 | ideal J = system("freegb",I,d,nvars(r)); |
---|
2230 | lpKDimCheck(J); |
---|
2231 | sickle(J,1,1,1,d); // dimension is 24872 |
---|
2232 | |
---|
2233 | |
---|
2234 | LIB "fpadim.lib"; |
---|
2235 | ring r = 0,(x,y,z),dp; |
---|
2236 | int d =10; // degree |
---|
2237 | def R = freeAlgebra(r, d); |
---|
2238 | setring R; |
---|
2239 | ideal I = x*y + y*z, x*x + x*y - y*x - y*y; |
---|
2240 | option(prot); |
---|
2241 | option(redSB);option(redTail);option(mem); |
---|
2242 | ideal J = system("freegb",I,d,3); |
---|
2243 | lpKDimCheck(J); |
---|
2244 | sickle(J,1,1,1,d); |
---|
2245 | */ |
---|
2246 | |
---|
2247 | |
---|
2248 | /* |
---|
2249 | Example for Compute GK dimension: |
---|
2250 | returns a ring which contains an ideal I |
---|
2251 | run gkDim(I) inside this ring and it should return 2n (the GK dimension |
---|
2252 | of n-th Weyl algebra including evaluation operators). |
---|
2253 | |
---|
2254 | static proc createWeylEx(int n, int d) |
---|
2255 | " |
---|
2256 | " |
---|
2257 | { |
---|
2258 | int baseringdef; |
---|
2259 | if (defined(basering)) // if a basering is defined, it should be saved for later use |
---|
2260 | { |
---|
2261 | def save = basering; |
---|
2262 | baseringdef = 1; |
---|
2263 | } |
---|
2264 | ring r = 0,(d(1..n),x(1..n),e(1..n)),dp; |
---|
2265 | def R = freeAlgebra(r, d); |
---|
2266 | setring R; |
---|
2267 | ideal I; int i,j; |
---|
2268 | |
---|
2269 | for (i = 1; i <= n; i++) |
---|
2270 | { |
---|
2271 | for (j = i+1; j<= n; j++) |
---|
2272 | { |
---|
2273 | I[size(I)+1] = lpMult(var(i),var(j)); |
---|
2274 | } |
---|
2275 | } |
---|
2276 | |
---|
2277 | for (i = 1; i <= n; i++) |
---|
2278 | { |
---|
2279 | for (j = i+1; j<= n; j++) |
---|
2280 | { |
---|
2281 | I[size(I)+1] = lpMult(var(n+i),var(n+j)); |
---|
2282 | } |
---|
2283 | } |
---|
2284 | for (i = 1; i <= n; i++) |
---|
2285 | { |
---|
2286 | for (j = 1; j<= n; j++) |
---|
2287 | { |
---|
2288 | I[size(I)+1] = lpMult(var(i),var(n+j)); |
---|
2289 | } |
---|
2290 | } |
---|
2291 | for (i = 1; i <= n; i++) |
---|
2292 | { |
---|
2293 | for (j = 1; j<= n; j++) |
---|
2294 | { |
---|
2295 | I[size(I)+1] = lpMult(var(i),var(2*n+j)); |
---|
2296 | } |
---|
2297 | } |
---|
2298 | for (i = 1; i <= n; i++) |
---|
2299 | { |
---|
2300 | for (j = 1; j<= n; j++) |
---|
2301 | { |
---|
2302 | I[size(I)+1] = lpMult(var(2*n+i),var(n+j)); |
---|
2303 | } |
---|
2304 | } |
---|
2305 | for (i = 1; i <= n; i++) |
---|
2306 | { |
---|
2307 | for (j = 1; j<= n; j++) |
---|
2308 | { |
---|
2309 | I[size(I)+1] = lpMult(var(2*n+i),var(2*n+j)); |
---|
2310 | } |
---|
2311 | } |
---|
2312 | I = simplify(I,2+4); |
---|
2313 | I = letplaceGBasis(I); |
---|
2314 | export(I); |
---|
2315 | if (baseringdef == 1) {setring save;} |
---|
2316 | return(R); |
---|
2317 | } |
---|
2318 | |
---|
2319 | proc TestGKAuslander3() |
---|
2320 | { |
---|
2321 | ring r = (0,q),(z,x,y),(dp(2),dp(2)); |
---|
2322 | def R = freeAlgebra(r, 5); // constructs a Letterplace ring |
---|
2323 | R; setring R; // sets basering to Letterplace ring |
---|
2324 | ideal I; |
---|
2325 | I = q*x*y - y*x, z*y - y*z, z*x - x*z; |
---|
2326 | I = letplaceGBasis(I); |
---|
2327 | lpGkDim(I); // must be 3 |
---|
2328 | I = x*y*z - y*x, z*y - y*z, z*x - x*z;//gkDim = 2 |
---|
2329 | I = letplaceGBasis(I); // not finite BUT contains a poly in x,y only |
---|
2330 | lpGkDim(I); // must be 4 |
---|
2331 | |
---|
2332 | ring r = 0,(y,x,z),dp; |
---|
2333 | def R = freeAlgebra(r, 10); // constructs a Letterplace ring |
---|
2334 | R; setring R; // sets basering to Letterplace ring |
---|
2335 | ideal I; |
---|
2336 | I = x*y*z - y*x, z*y - y*z, z*x - x*z;//gkDim = 2 |
---|
2337 | I = letplaceGBasis(I); // computed as it would be homogenized; infinite |
---|
2338 | poly p = x*y*y*x-y*x*x*y; |
---|
2339 | lpNF(p, I); // 0 as expected |
---|
2340 | |
---|
2341 | // with inverse of z |
---|
2342 | ring r = 0,(iz,z,x,y),dp; |
---|
2343 | def R = freeAlgebra(r, 11); // constructs a Letterplace ring |
---|
2344 | R; setring R; // sets basering to Letterplace ring |
---|
2345 | ideal I; |
---|
2346 | I = x*y*z - y*x, z*y - y*z, z*x - x*z, |
---|
2347 | iz*y - y*iz, iz*x - x*iz, iz*z-1, z*iz -1; |
---|
2348 | I = letplaceGBasis(I); // |
---|
2349 | setring r; |
---|
2350 | def R2 = freeAlgebra(r, 23); // constructs a Letterplace ring |
---|
2351 | setring R2; // sets basering to Letterplace ring |
---|
2352 | ideal I = imap(R,I); |
---|
2353 | lpGkDim(I); |
---|
2354 | |
---|
2355 | |
---|
2356 | ring r = 0,(t,z,x,y),(dp,dp); |
---|
2357 | def R = freeAlgebra(r, 20); // constructs a Letterplace ring |
---|
2358 | R; setring R; // sets basering to Letterplace ring |
---|
2359 | ideal I; |
---|
2360 | I = x*y*z - y*x*t, z*y - y*z, z*x - x*z, |
---|
2361 | t*y - y*t, t*x - x*t, t*z - z*t;//gkDim = 2 |
---|
2362 | I = letplaceGBasis(I); // computed as it would be homogenized; infinite |
---|
2363 | LIB "elim.lib"; |
---|
2364 | ideal Inoz = nselect(I,intvec(2,6,10,14,18,22,26,30)); |
---|
2365 | for(int i=1; i<=20; i++) |
---|
2366 | { |
---|
2367 | Inoz=subst(Inoz,t(i),1); |
---|
2368 | } |
---|
2369 | ideal J = x*y*y*x-y*x*x*y; |
---|
2370 | J = letplaceGBasis(J); |
---|
2371 | |
---|
2372 | poly p = x*y*y*x-y*x*x*y; |
---|
2373 | lpNF(p, I); // 0 as expected |
---|
2374 | |
---|
2375 | ring r2 = 0,(x,y),dp; |
---|
2376 | def R2 = freeAlgebra(r2, 50); // constructs a Letterplace ring |
---|
2377 | setring R2; |
---|
2378 | ideal J = x*y*y*x-y*x*x*y; |
---|
2379 | J = letplaceGBasis(J); |
---|
2380 | } |
---|
2381 | |
---|
2382 | */ |
---|
2383 | |
---|
2384 | |
---|
2385 | /* more tests : downup algebra A |
---|
2386 | LIB "fpadim.lib"; |
---|
2387 | ring r = (0,a,b,g),(x,y),Dp; |
---|
2388 | def R = freeAlgebra(r, 6); // constructs a Letterplace ring |
---|
2389 | setring R; |
---|
2390 | poly F1 = g*x; |
---|
2391 | poly F2 = g*y; |
---|
2392 | ideal J = x*x*y-a*x*y*x - b*y*x*x - F1, |
---|
2393 | x*y*y-a*y*x*y - b*y*y*x - F2; |
---|
2394 | J = letplaceGBasis(J); |
---|
2395 | lpGkDim(J); // 3 == correct |
---|
2396 | |
---|
2397 | // downup algebra B |
---|
2398 | LIB "fpadim.lib"; |
---|
2399 | ring r = (0,a,b,g, p(1..7),q(1..7)),(x,y),Dp; |
---|
2400 | def R = freeAlgebra(r, 6); // constructs a Letterplace ring |
---|
2401 | setring R; |
---|
2402 | ideal imn = 1, y*y*y, x*y, y*x, x*x, y*y, x, y; |
---|
2403 | int i; |
---|
2404 | poly F1, F2; |
---|
2405 | for(i=1;i<=7;i++) |
---|
2406 | { |
---|
2407 | F1 = F1 + p(i)*imn[i]; |
---|
2408 | F2 = F2 + q(i)*imn[i]; |
---|
2409 | } |
---|
2410 | ideal J = x*x*y-a*x*y*x - b*y*x*x - F1, |
---|
2411 | x*y*y-a*y*x*y - b*y*y*x - F2; |
---|
2412 | J = letplaceGBasis(J); |
---|
2413 | lpGkDim(J); // 3 == correct |
---|
2414 | */ |
---|