1 | /////////////////////////////////////////////////////// |
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2 | version="$Id$"; |
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3 | category="Noncommutative"; |
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4 | info=" |
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5 | LIBRARY: fpadim.lib Algorithms for quotient algebras in the letterplace case |
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6 | AUTHORS: Grischa Studzinski, grischa.studzinski@rwth-aachen.de |
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7 | @* Viktor Levandovskyy, viktor.levandovskyy@math.rwth-aachen.de |
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8 | @* Karim Abou Zeid, karim.abou.zeid@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 |
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13 | |
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14 | OVERVIEW: Given the free algebra A = K<x_1,...,x_n> and a (finite) Groebner basis |
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15 | @* GB = {g_1,..,g_w}, one is interested in the K-dimension and in the |
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16 | @* explicit K-basis of A/<GB>. |
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17 | @* Therefore one is interested in the following data: |
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18 | @* - the Ufnarovskij graph induced by GB |
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19 | @* - the mistletoes of A/<GB> |
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20 | @* - the K-dimension of A/<GB> |
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21 | @* - the Hilbert series of A/<GB> |
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22 | @* |
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23 | @* The Ufnarovskij graph is used to determine whether A/<GB> has finite |
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24 | @* K-dimension. One has to check if the graph contains cycles. |
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25 | @* For the whole theory we refer to [ufna]. Given a |
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26 | @* reduced set of monomials GB one can define the basis tree, whose vertex |
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27 | @* set V consists of all normal monomials w.r.t. GB. For every two |
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28 | @* monomials m_1, m_2 in V there is a direct edge from m_1 to m_2, if and |
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29 | @* only if there exists x_k in {x_1,..,x_n}, such that m_1*x_k = m_2. The |
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30 | @* set M = {m in V | there is no edge from m to another monomial in V} is |
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31 | @* called the set of mistletoes. As one can easily see it consists of |
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32 | @* the endpoints of the graph. Since there is a unique path to every |
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33 | @* monomial in V the whole graph can be described only from the knowledge |
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34 | @* of the mistletoes. Note that V corresponds to a basis of A/<GB>, so |
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35 | @* knowing the mistletoes we know a K-basis. The name mistletoes was given |
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36 | @* to those points because of these miraculous value and the algorithm is |
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37 | @* named sickle, because a sickle is the tool to harvest mistletoes. |
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38 | @* For more details see [studzins]. This package uses the Letterplace |
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39 | @* format introduced by [lls]. The algebra can either be represented as a |
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40 | @* Letterplace ring or via integer vectors: Every variable will only be |
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41 | @* represented by its number, so variable one is represented as 1, |
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42 | @* variable two as 2 and so on. The monomial x_1*x_3*x_2 for example will |
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43 | @* be stored as (1,3,2). Multiplication is concatenation. Note that there |
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44 | @* is no algorithm for computing the normal form yet, but for our case it |
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45 | @* is not needed. Note that the name fpadim.lib is short for dimensions of |
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46 | @* finite presented algebras. |
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47 | @* |
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48 | |
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49 | REFERENCES: |
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50 | |
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51 | @* [ufna] Ufnarovskij: Combinatorical and asymptotic methods in algebra, 1990 |
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52 | @* [lls] Levandovskyy, La Scala: Letterplace ideals and non-commutative |
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53 | Groebner bases, 2009 |
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54 | @* [studzins] Studzinski: Dimension computations in non-commutative, |
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55 | associative algebras, Diploma thesis, RWTH Aachen, 2010 |
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56 | |
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57 | ASSUMPTIONS: |
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58 | @* - basering is always a Letterplace ring |
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59 | @* - all intvecs correspond to Letterplace monomials |
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60 | @* - if you specify a different degree bound d, |
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61 | d <= attrib(basering,uptodeg) holds |
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62 | @* In the procedures below, 'iv' stands for intvec representation |
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63 | and 'lp' for the letterplace representation of monomials |
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64 | |
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65 | PROCEDURES: |
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66 | |
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67 | lpGkDim(G); computes the Gelfand Kirillov dimension of A/<G> |
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68 | ivDHilbert(L,n[,d]); computes the K-dimension and the Hilbert series |
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69 | ivDHilbertSickle(L,n[,d]); computes mistletoes, K-dimension and Hilbert series |
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70 | ivDimCheck(L,n); checks if the K-dimension of A/<L> is infinite |
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71 | lpGlDimBound(G); computes upper bound of global dimension of A/<G> |
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72 | ivHilbert(L,n[,d]); computes the Hilbert series of A/<L> in intvec format |
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73 | ivKDim(L,n[,d]); computes the K-dimension of A/<L> in intvec format |
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74 | ivMis2Base(M); computes a K-basis of the factor algebra |
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75 | ivMis2Dim(M); computes the K-dimension of the factor algebra |
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76 | ivOrdMisLex(M); orders a list of intvecs lexicographically |
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77 | ivSickle(L,n[,d]); computes the mistletoes of A/<L> in intvec format |
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78 | ivSickleHil(L,n[,d]); computes the mistletoes and Hilbert series of A/<L> |
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79 | ivSickleDim(L,n[,d]); computes the mistletoes and the K-dimension of A/<L> |
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80 | lpDHilbert(G[,d,n]); computes the K-dimension and Hilbert series of A/<G> |
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81 | lpDHilbertSickle(G[,d,n]); computes mistletoes, K-dimension and Hilbert series |
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82 | lpHilbert(G[,d,n]); computes the Hilbert series of A/<G> in lp format |
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83 | lpDimCheck(G); checks if the K-dimension of A/<G> is infinite |
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84 | lpKDim(G[,d,n]); computes the K-dimension of A/<G> in lp format |
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85 | lpMis2Base(M); computes a K-basis of the factor algebra |
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86 | lpMis2Dim(M); computes the K-dimension of the factor algebra |
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87 | lpOrdMisLex(M); orders an ideal of lp-monomials lexicographically |
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88 | lpSickle(G[,d,n]); computes the mistletoes of A/<G> in lp format |
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89 | lpSickleHil(G[,d,n]); computes the mistletoes and Hilbert series of A/<G> |
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90 | lpSickleDim(G[,d,n]); computes the mistletoes and the K-dimension of A/<G> |
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91 | sickle(G[,m,d,h]); can be used to access all lp main procedures |
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92 | |
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93 | |
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94 | ivL2lpI(L); transforms a list of intvecs into an ideal of lp monomials |
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95 | iv2lp(I); transforms an intvec into the corresponding monomial |
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96 | iv2lpList(L); transforms a list of intmats into an ideal of lp monomials |
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97 | iv2lpMat(M); transforms an intmat into an ideal of lp monomials |
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98 | lp2iv(p); transforms a polynomial into the corresponding intvec |
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99 | lp2ivId(G); transforms an ideal into the corresponding list of intmats |
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100 | lpId2ivLi(G); transforms a lp-ideal into the corresponding list of intvecs |
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101 | |
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102 | SEE ALSO: freegb_lib |
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103 | "; |
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104 | |
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105 | LIB "freegb.lib"; //for letterplace rings |
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106 | LIB "general.lib";//for sorting mistletoes |
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107 | |
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108 | ///////////////////////////////////////////////////////// |
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109 | |
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110 | |
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111 | //--------------- auxiliary procedures ------------------ |
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112 | |
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113 | static proc allVars(list L, intvec P, int n) |
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114 | "USAGE: allVars(L,P,n); L a list of intmats, P an intvec, n an integer |
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115 | RETURN: int, 0 if all variables are contained in the quotient algebra, 1 otherwise |
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116 | " |
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117 | {int i,j,r; |
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118 | intvec V; |
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119 | for (i = 1; i <= size(P); i++) {if (P[i] == 1){ j = i; break;}} |
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120 | V = L[j][1..nrows(L[j]),1]; |
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121 | for (i = 1; i <= n; i++) {if (isInVec(i,V) == 0) {r = 1; break;}} |
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122 | if (r == 0) {return(1);} |
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123 | else {return(0);} |
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124 | } |
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125 | |
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126 | static proc checkAssumptions(int d, list L) |
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127 | "PURPOSE: Checks, if all the Assumptions are holding |
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128 | " |
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129 | {if (typeof(attrib(basering,"isLetterplaceRing"))=="string") {ERROR("Basering is not a Letterplace ring!");} |
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130 | if (d > attrib(basering,"uptodeg")) {ERROR("Specified degree bound exceeds ring parameter!");} |
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131 | int i; |
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132 | for (i = 1; i <= size(L); i++) |
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133 | {if (entryViolation(L[i], attrib(basering,"lV"))) |
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134 | {ERROR("Not allowed monomial/intvec found!");} |
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135 | } |
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136 | return(); |
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137 | } |
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138 | |
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139 | static proc createStartMat(int d, int n) |
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140 | "USAGE: createStartMat(d,n); d, n integers |
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141 | RETURN: intmat |
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142 | PURPOSE:Creating the intmat with all normal monomials in n variables and of degree d to start with |
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143 | NOTE: d has to be > 0 |
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144 | " |
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145 | {intmat M[(n^d)][d]; |
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146 | int i1,i2,i3,i4; |
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147 | for (i1 = 1; i1 <= d; i1++) //Spalten |
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148 | {i2 = 1; //durchlaeuft Zeilen |
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149 | while (i2 <= (n^d)) |
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150 | {for (i3 = 1; i3 <= n; i3++) |
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151 | {for (i4 = 1; i4 <= (n^(i1-1)); i4++) |
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152 | {M[i2,i1] = i3; |
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153 | i2 = i2 + 1; |
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154 | } |
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155 | } |
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156 | } |
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157 | } |
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158 | return(M); |
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159 | } |
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160 | |
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161 | static proc createStartMat1(int n, intmat M) |
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162 | "USAGE: createStartMat1(n,M); n an integer, M an intmat |
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163 | RETURN: intmat, with all variables except those in M |
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164 | " |
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165 | {int i; |
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166 | intvec V,Vt; |
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167 | V = M[(1..nrows(M)),1]; |
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168 | for (i = 1; i <= size(V); i++) {if (isInVec(i,V) == 0) {Vt = Vt,i;}} |
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169 | if (Vt == 0) {intmat S; return(S);} |
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170 | else {Vt = Vt[2..size(Vt)]; intmat S [size(Vt)][1]; S[1..size(Vt),1] = Vt; return(S);} |
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171 | } |
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172 | |
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173 | static proc entryViolation(intmat M, int n) |
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174 | "PURPOSE:checks, if all entries in M are variable-related |
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175 | " |
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176 | {int i,j; |
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177 | for (i = 1; i <= nrows(M); i++) |
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178 | {for (j = 1; j <= ncols(M); j++) |
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179 | {if(!((1<=M[i,j])&&(M[i,j]<=n))) {return(1);}} |
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180 | } |
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181 | return(0); |
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182 | } |
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183 | |
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184 | static proc findDimen(intvec V, int n, list L, intvec P, list #) |
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185 | "USAGE: findDimen(V,n,L,P,degbound); V,P intvecs, n, an integer, L a list, |
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186 | @* degbound an optional integer |
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187 | RETURN: int |
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188 | PURPOSE:Computing the K-dimension of the quotient algebra |
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189 | " |
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190 | {int degbound = 0; |
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191 | if (size(#) > 0) {if (#[1] > 0) {degbound = #[1];}} |
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192 | int dimen,i,j,w,it; |
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193 | intvec Vt,Vt2; |
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194 | module M; |
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195 | if (degbound == 0) |
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196 | {for (i = 1; i <= n; i++) |
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197 | {Vt = V, i; w = 0; |
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198 | for (j = 1; j<= size(P); j++) |
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199 | {if (P[j] <= size(Vt)) |
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200 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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201 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
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202 | } |
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203 | } |
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204 | if (w == 0) |
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205 | {vector Vtt; |
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206 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
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207 | M = M,Vtt; |
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208 | kill Vtt; |
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209 | } |
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210 | } |
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211 | if (size(M) == 0) {return(0);} |
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212 | else |
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213 | {M = simplify(M,2); |
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214 | for (i = 1; i <= size(M); i++) |
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215 | {kill Vt; intvec Vt; |
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216 | for (j =1; j <= size(M[i]); j++){Vt[j] = int(leadcoef(M[i][j]));} |
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217 | dimen = dimen + 1 + findDimen(Vt,n,L,P); |
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218 | } |
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219 | return(dimen); |
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220 | } |
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221 | } |
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222 | else |
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223 | {if (size(V) > degbound) {ERROR("monomial exceeds degreebound");} |
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224 | if (size(V) == degbound) {return(0);} |
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225 | for (i = 1; i <= n; i++) |
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226 | {Vt = V, i; w = 0; |
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227 | for (j = 1; j<= size(P); j++) |
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228 | {if (P[j] <= size(Vt)) |
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229 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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230 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
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231 | } |
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232 | } |
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233 | if (w == 0) {vector Vtt; |
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234 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
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235 | M = M,Vtt; |
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236 | kill Vtt; |
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237 | } |
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238 | } |
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239 | if (size(M) == 0) {return(0);} |
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240 | else |
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241 | {M = simplify(M,2); |
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242 | for (i = 1; i <= size(M); i++) |
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243 | {kill Vt; intvec Vt; |
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244 | for (j =1; j <= size(M[i]); j++){Vt[j] = int(leadcoef(M[i][j]));} |
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245 | dimen = dimen + 1 + findDimen(Vt,n,L,P,degbound); |
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246 | } |
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247 | return(dimen); |
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248 | } |
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249 | } |
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250 | } |
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251 | |
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252 | static proc findCycle(intvec V, list L, intvec P, int n, int ld, module M) |
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253 | "USAGE: |
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254 | RETURN: int, 1 if Ufn-graph contains a cycle, or 0 otherwise |
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255 | PURPOSE:Searching the Ufnarovskij graph for cycles |
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256 | " |
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257 | {int i,j,w,r;intvec Vt,Vt2; |
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258 | int it, it2; |
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259 | if (size(V) < ld) |
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260 | {for (i = 1; i <= n; i++) |
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261 | {Vt = V,i; w = 0; |
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262 | for (j = 1; j <= size(P); j++) |
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263 | {if (P[j] <= size(Vt)) |
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264 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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265 | if (isInMat(Vt2,L[j]) > 0) |
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266 | {w = 1; break;} |
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267 | } |
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268 | } |
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269 | if (w == 0) {r = findCycle(Vt,L,P,n,ld,M);} |
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270 | if (r == 1) {break;} |
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271 | } |
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272 | return(r); |
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273 | } |
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274 | else |
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275 | {j = size(M); |
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276 | if (j > 0) |
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277 | { |
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278 | intmat Mt[j][nrows(M)]; |
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279 | for (it = 1; it <= j; it++) |
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280 | { for(it2 = 1; it2 <= nrows(M);it2++) |
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281 | {Mt[it,it2] = int(leadcoef(M[it2,it]));} |
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282 | } |
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283 | Vt = V[(size(V)-ld+1)..size(V)]; |
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284 | //Mt; type(Mt);Vt;type(Vt); |
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285 | if (isInMat(Vt,Mt) > 0) {return(1);} |
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286 | else |
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287 | {vector Vtt; |
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288 | for (it =1; it <= size(Vt); it++) |
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289 | {Vtt = Vtt + Vt[it]*gen(it);} |
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290 | M = M,Vtt; |
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291 | kill Vtt; |
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292 | for (i = 1; i <= n; i++) |
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293 | {Vt = V,i; w = 0; |
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294 | for (j = 1; j <= size(P); j++) |
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295 | {if (P[j] <= size(Vt)) |
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296 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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297 | //L[j]; type(L[j]);Vt2;type(Vt2); |
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298 | if (isInMat(Vt2,L[j]) > 0) |
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299 | {w = 1; break;} |
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300 | } |
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301 | } |
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302 | if (w == 0) {r = findCycle(Vt,L,P,n,ld,M);} |
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303 | if (r == 1) {break;} |
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304 | } |
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305 | return(r); |
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306 | } |
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307 | } |
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308 | else |
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309 | { Vt = V[(size(V)-ld+1)..size(V)]; |
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310 | vector Vtt; |
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311 | for (it = 1; it <= size(Vt); it++) |
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312 | {Vtt = Vtt + Vt[it]*gen(it);} |
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313 | M = Vtt; |
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314 | kill Vtt; |
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315 | for (i = 1; i <= n; i++) |
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316 | {Vt = V,i; w = 0; |
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317 | for (j = 1; j <= size(P); j++) |
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318 | {if (P[j] <= size(Vt)) |
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319 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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320 | //L[j]; type(L[j]);Vt2;type(Vt2); |
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321 | if (isInMat(Vt2,L[j]) > 0) |
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322 | {w = 1; break;} |
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323 | } |
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324 | } |
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325 | if (w == 0) {r = findCycle(Vt,L,P,n,ld,M);} |
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326 | if (r == 1) {break;} |
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327 | } |
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328 | return(r); |
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329 | } |
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330 | } |
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331 | } |
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332 | |
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333 | |
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334 | static proc findCycleDFS(int i, intmat T, intvec V) |
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335 | " |
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336 | PURPOSE: |
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337 | this is a classical deep-first search for cycles contained in a graph given by an intmat |
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338 | " |
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339 | { |
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340 | intvec rV; |
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341 | int k,k1,t; |
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342 | int j = V[size(V)]; |
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343 | if (T[j,i] > 0) {return(V);} |
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344 | else |
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345 | { |
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346 | for (k = 1; k <= ncols(T); k++) |
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347 | { |
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348 | t = 0; |
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349 | if (T[j,k] > 0) |
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350 | { |
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351 | for (k1 = 1; k1 <= size(V); k1++) {if (V[k1] == k) {t = 1; break;}} |
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352 | if (t == 0) |
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353 | { |
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354 | rV = V; |
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355 | rV[size(rV)+1] = k; |
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356 | rV = findCycleDFS(i,T,rV); |
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357 | if (rV[1] > -1) {return(rV);} |
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358 | } |
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359 | } |
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360 | } |
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361 | } |
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362 | return(intvec(-1)); |
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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 | static proc findHCoeff(intvec V,int n,list L,intvec P,intvec H,list #) |
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368 | "USAGE: findHCoeff(V,n,L,P,H,degbound); L a list of intmats, degbound an integer |
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369 | RETURN: intvec |
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370 | PURPOSE:Computing the coefficient of the Hilbert series (upto degree degbound) |
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371 | NOTE: Starting with a part of the Hilbert series we change the coefficient |
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372 | @* depending on how many basis elements we found on the actual branch |
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373 | " |
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374 | {int degbound = 0; |
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375 | if (size(#) > 0){if (#[1] > 0){degbound = #[1];}} |
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376 | int i,w,j,it; |
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377 | int h1 = 0; |
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378 | intvec Vt,Vt2,H1; |
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379 | module M; |
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380 | if (degbound == 0) |
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381 | {for (i = 1; i <= n; i++) |
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382 | {Vt = V, i; w = 0; |
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383 | for (j = 1; j<= size(P); j++) |
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384 | {if (P[j] <= size(Vt)) |
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385 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
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386 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
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387 | } |
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388 | } |
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389 | if (w == 0) |
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390 | {vector Vtt; |
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391 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
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392 | M = M,Vtt; |
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393 | kill Vtt; |
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394 | } |
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395 | } |
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396 | if (size(M) == 0) {return(H);} |
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397 | else |
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398 | {M = simplify(M,2); |
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399 | for (i = 1; i <= size(M); i++) |
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400 | {kill Vt; intvec Vt; |
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401 | for (j =1; j <= size(M[i]); j++) {Vt[j] = int(leadcoef(M[i][j]));} |
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402 | h1 = h1 + 1; H1 = findHCoeff(Vt,n,L,P,H1); |
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403 | } |
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404 | if (size(H1) < (size(V)+2)) {H1[(size(V)+2)] = h1;} |
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405 | else {H1[(size(V)+2)] = H1[(size(V)+2)] + h1;} |
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406 | H1 = H1 + H; |
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407 | return(H1); |
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408 | } |
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409 | } |
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410 | else |
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411 | {if (size(V) > degbound) {ERROR("monomial exceeds degreebound");} |
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412 | if (size(V) == degbound) {return(H);} |
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413 | for (i = 1; i <= n; i++) |
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414 | {Vt = V, i; w = 0; |
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415 | for (j = 1; j<= size(P); j++) |
---|
416 | {if (P[j] <= size(Vt)) |
---|
417 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
418 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
---|
419 | } |
---|
420 | } |
---|
421 | if (w == 0) |
---|
422 | {vector Vtt; |
---|
423 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
424 | M = M,Vtt; |
---|
425 | kill Vtt; |
---|
426 | } |
---|
427 | } |
---|
428 | if (size(M) == 0) {return(H);} |
---|
429 | else |
---|
430 | {M = simplify(M,2); |
---|
431 | for (i = 1; i <= size(M); i++) |
---|
432 | {kill Vt; intvec Vt; |
---|
433 | for (j =1; j <= size(M[i]); j++) |
---|
434 | {Vt[j] = int(leadcoef(M[i][j]));} |
---|
435 | h1 = h1 + 1; H1 = findHCoeff(Vt,n,L,P,H1,degbound); |
---|
436 | } |
---|
437 | if (size(H1) < (size(V)+2)) { H1[(size(V)+2)] = h1;} |
---|
438 | else {H1[(size(V)+2)] = H1[(size(V)+2)] + h1;} |
---|
439 | H1 = H1 + H; |
---|
440 | return(H1); |
---|
441 | } |
---|
442 | } |
---|
443 | } |
---|
444 | |
---|
445 | static proc findHCoeffMis(intvec V, int n, list L, intvec P, list R,list #) |
---|
446 | "USAGE: findHCoeffMis(V,n,L,P,R,degbound); degbound an optional integer, L a |
---|
447 | @* list of Intmats, R |
---|
448 | RETURN: list |
---|
449 | PURPOSE:Computing the coefficients of the Hilbert series and the Mistletoes all |
---|
450 | @* at once |
---|
451 | " |
---|
452 | {int degbound = 0; |
---|
453 | if (size(#) > 0) {if (#[1] > 0) {degbound = #[1];}} |
---|
454 | int i,w,j,h1; |
---|
455 | intvec Vt,Vt2,H1; int it; |
---|
456 | module M; |
---|
457 | if (degbound == 0) |
---|
458 | {for (i = 1; i <= n; i++) |
---|
459 | {Vt = V, i; w = 0; |
---|
460 | for (j = 1; j<= size(P); j++) |
---|
461 | {if (P[j] <= size(Vt)) |
---|
462 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
463 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
---|
464 | } |
---|
465 | } |
---|
466 | if (w == 0) |
---|
467 | {vector Vtt; |
---|
468 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
469 | M = M,Vtt; |
---|
470 | kill Vtt; |
---|
471 | } |
---|
472 | } |
---|
473 | if (size(M) == 0) {if (size(R) < 2){R[2] = list(V);} else {R[2] = R[2] + list(V);} return(R);} |
---|
474 | else |
---|
475 | {M = simplify(M,2); |
---|
476 | for (i = 1; i <= size(M); i++) |
---|
477 | {kill Vt; intvec Vt; |
---|
478 | for (j =1; j <= size(M[i]); j++) |
---|
479 | {Vt[j] = int(leadcoef(M[i][j]));} |
---|
480 | if (size(R[1]) < (size(V)+2)) { R[1][(size(V)+2)] = 1;} |
---|
481 | else |
---|
482 | {R[1][(size(V)+2)] = R[1][(size(V)+2)] + 1;} |
---|
483 | R = findHCoeffMis(Vt,n,L,P,R); |
---|
484 | } |
---|
485 | return(R); |
---|
486 | } |
---|
487 | } |
---|
488 | else |
---|
489 | {if (size(V) > degbound) {ERROR("monomial exceeds degreebound");} |
---|
490 | if (size(V) == degbound) |
---|
491 | {if (size(R) < 2){R[2] = list (V);} |
---|
492 | else{R[2] = R[2] + list (V);} |
---|
493 | return(R); |
---|
494 | } |
---|
495 | for (i = 1; i <= n; i++) |
---|
496 | {Vt = V, i; w = 0; |
---|
497 | for (j = 1; j<= size(P); j++) |
---|
498 | {if (P[j] <= size(Vt)) |
---|
499 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
500 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
---|
501 | } |
---|
502 | } |
---|
503 | if (w == 0) |
---|
504 | {vector Vtt; |
---|
505 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
506 | M = M,Vtt; |
---|
507 | kill Vtt; |
---|
508 | } |
---|
509 | } |
---|
510 | if (size(M) == 0) {if (size(R) < 2){R[2] = list(V);} else {R[2] = R[2] + list(V);} return(R);} |
---|
511 | else |
---|
512 | {M = simplify(M,2); |
---|
513 | for (i = 1; i <= ncols(M); i++) |
---|
514 | {kill Vt; intvec Vt; |
---|
515 | for (j =1; j <= size(M[i]); j++) |
---|
516 | {Vt[j] = int(leadcoef(M[i][j]));} |
---|
517 | if (size(R[1]) < (size(V)+2)) { R[1][(size(V)+2)] = 1;} |
---|
518 | else |
---|
519 | {R[1][(size(V)+2)] = R[1][(size(V)+2)] + 1;} |
---|
520 | R = findHCoeffMis(Vt,n,L,P,R,degbound); |
---|
521 | } |
---|
522 | return(R); |
---|
523 | } |
---|
524 | } |
---|
525 | } |
---|
526 | |
---|
527 | |
---|
528 | static proc findMisDim(intvec V,int n,list L,intvec P,list R,list #) |
---|
529 | "USAGE: |
---|
530 | RETURN: list |
---|
531 | PURPOSE:Computing the K-dimension and the Mistletoes all at once |
---|
532 | " |
---|
533 | {int degbound = 0; |
---|
534 | if (size(#) > 0) {if (#[1] > 0) {degbound = #[1];}} |
---|
535 | int dimen,i,j,w; |
---|
536 | intvec Vt,Vt2; int it; |
---|
537 | module M; |
---|
538 | if (degbound == 0) |
---|
539 | {for (i = 1; i <= n; i++) |
---|
540 | {Vt = V, i; w = 0; |
---|
541 | for (j = 1; j<= size(P); j++) |
---|
542 | {if (P[j] <= size(Vt)) |
---|
543 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
544 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
---|
545 | } |
---|
546 | } |
---|
547 | if (w == 0) |
---|
548 | {vector Vtt; |
---|
549 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
550 | M = M,Vtt; |
---|
551 | kill Vtt; |
---|
552 | } |
---|
553 | } |
---|
554 | if (size(M) == 0) |
---|
555 | {if (size(R) < 2){R[2] = list (V);} |
---|
556 | else{R[2] = R[2] + list(V);} |
---|
557 | return(R); |
---|
558 | } |
---|
559 | else |
---|
560 | {M = simplify(M,2); |
---|
561 | for (i = 1; i <= size(M); i++) |
---|
562 | {kill Vt; intvec Vt; |
---|
563 | for (j =1; j <= size(M[i]); j++){Vt[j] = int(leadcoef(M[i][j]));} |
---|
564 | R[1] = R[1] + 1; R = findMisDim(Vt,n,L,P,R); |
---|
565 | } |
---|
566 | return(R); |
---|
567 | } |
---|
568 | } |
---|
569 | else |
---|
570 | {if (size(V) > degbound) {ERROR("monomial exceeds degreebound");} |
---|
571 | if (size(V) == degbound) |
---|
572 | {if (size(R) < 2){R[2] = list (V);} |
---|
573 | else{R[2] = R[2] + list (V);} |
---|
574 | return(R); |
---|
575 | } |
---|
576 | for (i = 1; i <= n; i++) |
---|
577 | {Vt = V, i; w = 0; |
---|
578 | for (j = 1; j<= size(P); j++) |
---|
579 | {if (P[j] <= size(Vt)) |
---|
580 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
581 | if (isInMat(Vt2,L[j]) > 0) {w = 1; break;} |
---|
582 | } |
---|
583 | } |
---|
584 | if (w == 0) |
---|
585 | {vector Vtt; |
---|
586 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
587 | M = M,Vtt; |
---|
588 | kill Vtt; |
---|
589 | } |
---|
590 | } |
---|
591 | if (size(M) == 0) |
---|
592 | {if (size(R) < 2){R[2] = list (V);} |
---|
593 | else{R[2] = R[2] + list(V);} |
---|
594 | return(R); |
---|
595 | } |
---|
596 | else |
---|
597 | {M = simplify(M,2); |
---|
598 | for (i = 1; i <= size(M); i++) |
---|
599 | {kill Vt; intvec Vt; |
---|
600 | for (j =1; j <= size(M[i]); j++){Vt[j] = int(leadcoef(M[i][j]));} |
---|
601 | R[1] = R[1] + 1; R = findMisDim(Vt,n,L,P,R,degbound); |
---|
602 | } |
---|
603 | return(R); |
---|
604 | } |
---|
605 | } |
---|
606 | } |
---|
607 | |
---|
608 | |
---|
609 | static proc findmistletoes(intvec V, int n, list L, intvec P, list #) |
---|
610 | "USAGE: findmistletoes(V,n,L,P,degbound); V a normal word, n the number of |
---|
611 | @* variables, L the GB, P the occuring degrees, |
---|
612 | @* and degbound the (optional) degreebound |
---|
613 | RETURN: list |
---|
614 | PURPOSE:Computing mistletoes starting in V |
---|
615 | NOTE: V has to be normal w.r.t. L, it will not be checked for being so |
---|
616 | " |
---|
617 | {int degbound = 0; |
---|
618 | if (size(#) > 0) {if (#[1] > 0) {degbound = #[1];}} |
---|
619 | list R; intvec Vt,Vt2; int it; |
---|
620 | int i,j; |
---|
621 | module M; |
---|
622 | if (degbound == 0) |
---|
623 | {int w; |
---|
624 | for (i = 1; i <= n; i++) |
---|
625 | {Vt = V,i; w = 0; |
---|
626 | for (j = 1; j <= size(P); j++) |
---|
627 | {if (P[j] <= size(Vt)) |
---|
628 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
629 | if (isInMat(Vt2,L[j]) > 0) |
---|
630 | {w = 1; break;} |
---|
631 | } |
---|
632 | } |
---|
633 | if (w == 0) |
---|
634 | {vector Vtt; |
---|
635 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
636 | M = M,Vtt; |
---|
637 | kill Vtt; |
---|
638 | } |
---|
639 | } |
---|
640 | if (size(M)==0) {R = V; return(R);} |
---|
641 | else |
---|
642 | {M = simplify(M,2); |
---|
643 | for (i = 1; i <= size(M); i++) |
---|
644 | {kill Vt; intvec Vt; |
---|
645 | for (j =1; j <= size(M[i]); j++){Vt[j] = int(leadcoef(M[i][j]));} |
---|
646 | R = R + findmistletoes(Vt,n,L,P); |
---|
647 | } |
---|
648 | return(R); |
---|
649 | } |
---|
650 | } |
---|
651 | else |
---|
652 | {if (size(V) > degbound) {ERROR("monomial exceeds degreebound");} |
---|
653 | if (size(V) == degbound) {R = V; return(R);} |
---|
654 | int w; |
---|
655 | for (i = 1; i <= n; i++) |
---|
656 | {Vt = V,i; w = 0; |
---|
657 | for (j = 1; j <= size(P); j++) |
---|
658 | {if (P[j] <= size(Vt)) |
---|
659 | {Vt2 = Vt[(size(Vt)-P[j]+1)..size(Vt)]; |
---|
660 | if (isInMat(Vt2,L[j]) > 0){w = 1; break;} |
---|
661 | } |
---|
662 | } |
---|
663 | if (w == 0) |
---|
664 | {vector Vtt; |
---|
665 | for (it = 1; it <= size(Vt); it++){Vtt = Vtt + Vt[it]*gen(it);} |
---|
666 | M = M,Vtt; |
---|
667 | kill Vtt; |
---|
668 | } |
---|
669 | } |
---|
670 | if (size(M) == 0) {R = V; return(R);} |
---|
671 | else |
---|
672 | {M = simplify(M,2); |
---|
673 | for (i = 1; i <= ncols(M); i++) |
---|
674 | {kill Vt; intvec Vt; |
---|
675 | for (j =1; j <= size(M[i]); j++) |
---|
676 | {Vt[j] = int(leadcoef(M[i][j]));} |
---|
677 | //Vt; typeof(Vt); size(Vt); |
---|
678 | R = R + findmistletoes(Vt,n,L,P,degbound); |
---|
679 | } |
---|
680 | return(R); |
---|
681 | } |
---|
682 | } |
---|
683 | } |
---|
684 | |
---|
685 | static proc growthAlg(intmat T, list #) |
---|
686 | " |
---|
687 | real algorithm for checking the growth of an algebra |
---|
688 | " |
---|
689 | { |
---|
690 | int s = 1; |
---|
691 | if (size(#) > 0) { s = #[1];} |
---|
692 | int j; |
---|
693 | int n = ncols(T); |
---|
694 | intvec NV,C; NV[n] = 0; int m,i; |
---|
695 | intmat T2[n][n] = T[1..n,1..n]; intmat N[n][n]; |
---|
696 | if (T2 == N) |
---|
697 | { |
---|
698 | for (i = 1; i <= n; i++) |
---|
699 | { |
---|
700 | if (m < T[n+1,i]) { m = T[n+1,i];} |
---|
701 | } |
---|
702 | return(m); |
---|
703 | } |
---|
704 | |
---|
705 | //first part: the diagonals |
---|
706 | for (i = s; i <= n; i++) |
---|
707 | { |
---|
708 | if (T[i,i] > 0) |
---|
709 | { |
---|
710 | if ((T[i,i] >= 1) && (T[n+1,i] > 0)) {return(-1);} |
---|
711 | if ((T[i,i] == 1) && (T[n+1,i] == 0)) |
---|
712 | { |
---|
713 | T[i,i] = 0; |
---|
714 | T[n+1,i] = 1; |
---|
715 | return(growthAlg(T)); |
---|
716 | } |
---|
717 | } |
---|
718 | } |
---|
719 | |
---|
720 | //second part: searching for the last but one vertices |
---|
721 | T2 = T2*T2; |
---|
722 | for (i = s; i <= n; i++) |
---|
723 | { |
---|
724 | if ((intvec(T[i,1..n]) <> intvec(0)) && (intvec(T2[i,1..n]) == intvec(0))) |
---|
725 | { |
---|
726 | for (j = 1; j <= n; j++) |
---|
727 | { |
---|
728 | if ((T[i,j] > 0) && (m < T[n+1,j])) {m = T[n+1,j];} |
---|
729 | } |
---|
730 | T[n+1,i] = T[n+1,i] + m; |
---|
731 | T[i,1..n] = NV; |
---|
732 | return(growthAlg(T)); |
---|
733 | } |
---|
734 | } |
---|
735 | m = 0; |
---|
736 | |
---|
737 | //third part: searching for circles |
---|
738 | for (i = s; i <= n; i++) |
---|
739 | { |
---|
740 | T2 = T[1..n,1..n]; |
---|
741 | C = findCycleDFS(i,T2, intvec(i)); |
---|
742 | if (C[1] > 0) |
---|
743 | { |
---|
744 | for (j = 2; j <= size(C); j++) |
---|
745 | { |
---|
746 | T[i,1..n] = T[i,1..n] + T[C[j],1..n]; |
---|
747 | T[C[j],1..n] = NV; |
---|
748 | } |
---|
749 | for (j = 2; j <= size(C); j++) |
---|
750 | { |
---|
751 | T[1..n,i] = T[1..n,i] + T[1..n,C[j]]; |
---|
752 | T[1..n,C[j]] = NV; |
---|
753 | } |
---|
754 | T[i,i] = T[i,i] - size(C) + 1; |
---|
755 | m = 0; |
---|
756 | for (j = 1; j <= size(C); j++) |
---|
757 | { |
---|
758 | m = m + T[n+1,C[j]]; |
---|
759 | } |
---|
760 | for (j = 1; j <= size(C); j++) |
---|
761 | { |
---|
762 | T[n+1,C[j]] = m; |
---|
763 | } |
---|
764 | return(growthAlg(T,i)); |
---|
765 | } |
---|
766 | else {ERROR("No Cycle found, something seems wrong! Please contact the authors.");} |
---|
767 | } |
---|
768 | |
---|
769 | m = 0; |
---|
770 | for (i = 1; i <= n; i++) |
---|
771 | { |
---|
772 | if (m < T[n+1,i]) |
---|
773 | { |
---|
774 | m = T[n+1,i]; |
---|
775 | } |
---|
776 | } |
---|
777 | return(m); |
---|
778 | } |
---|
779 | |
---|
780 | static proc GlDimSuffix(intvec v, intvec g) |
---|
781 | { |
---|
782 | //Computes the shortest r such that g is a suffix for vr |
---|
783 | //only valid for lex orderings? |
---|
784 | intvec r,gt,vt,lt,g2; |
---|
785 | int lg,lv,l,i,c,f; |
---|
786 | lg = size(g); lv = size(v); |
---|
787 | if (lg <= lv) |
---|
788 | { |
---|
789 | l = lv-lg; |
---|
790 | } |
---|
791 | else |
---|
792 | { |
---|
793 | l = 0; g2 = g[(lv+1)..lg]; |
---|
794 | g = g[1..lv]; lg = size(g); |
---|
795 | c = 1; |
---|
796 | } |
---|
797 | while (l < lv) |
---|
798 | { |
---|
799 | vt = v[(l+1)..lv]; |
---|
800 | gt = g[1..(lv-l)]; |
---|
801 | lt = size(gt); |
---|
802 | for (i = 1; i <= lt; i++) |
---|
803 | { |
---|
804 | if (vt[i]<>gt[i]) {l++; break;} |
---|
805 | } |
---|
806 | if (lt <=i ) { f = 1; break;} |
---|
807 | } |
---|
808 | if (f == 0) {return(g);} |
---|
809 | r = g[(lv-l+1)..lg]; |
---|
810 | if (c == 1) {r = r,g2;} |
---|
811 | return(r); |
---|
812 | } |
---|
813 | |
---|
814 | static proc isNormal(intvec V, list G) |
---|
815 | { |
---|
816 | int i,j,k,l; |
---|
817 | k = 0; |
---|
818 | for (i = 1; i <= size(G); i++) |
---|
819 | { |
---|
820 | if ( size(G[i]) <= size(V) ) |
---|
821 | { |
---|
822 | while ( size(G[i])+k <= size(V) ) |
---|
823 | { |
---|
824 | if ( G[i] == V[(1+k)..size(V)] ) {return(1);} |
---|
825 | } |
---|
826 | } |
---|
827 | } |
---|
828 | return(0); |
---|
829 | } |
---|
830 | |
---|
831 | static proc findDChain(list L) |
---|
832 | { |
---|
833 | list Li; int i,j; |
---|
834 | for (i = 1; i <= size(L); i++) {Li[i] = size(L[i]);} |
---|
835 | Li = sort(Li); Li = Li[1]; |
---|
836 | return(Li[size(Li)]); |
---|
837 | } |
---|
838 | |
---|
839 | static proc isInList(intvec V, list L) |
---|
840 | "USAGE: isInList(V,L); V an intvec, L a list of intvecs |
---|
841 | RETURN: int |
---|
842 | PURPOSE:Finding the position of V in L, returns 0, if V is not in M |
---|
843 | " |
---|
844 | {int i,n; |
---|
845 | n = 0; |
---|
846 | for (i = 1; i <= size(L); i++) {if (L[i] == V) {n = i; break;}} |
---|
847 | return(n); |
---|
848 | } |
---|
849 | |
---|
850 | static proc isInMat(intvec V, intmat M) |
---|
851 | "USAGE: isInMat(V,M);V an intvec, M an intmat |
---|
852 | RETURN: int |
---|
853 | PURPOSE:Finding the position of V in M, returns 0, if V is not in M |
---|
854 | " |
---|
855 | {if (size(V) <> ncols(M)) {return(0);} |
---|
856 | int i; |
---|
857 | intvec Vt; |
---|
858 | for (i = 1; i <= nrows(M); i++) |
---|
859 | {Vt = M[i,1..ncols(M)]; |
---|
860 | if ((V-Vt) == 0){return(i);} |
---|
861 | } |
---|
862 | return(0); |
---|
863 | } |
---|
864 | |
---|
865 | static proc isInVec(int v,intvec V) |
---|
866 | "USAGE: isInVec(v,V); v an integer,V an intvec |
---|
867 | RETURN: int |
---|
868 | PURPOSE:Finding the position of v in V, returns 0, if v is not in V |
---|
869 | " |
---|
870 | {int i,n; |
---|
871 | n = 0; |
---|
872 | for (i = 1; i <= size(V); i++) {if (V[i] == v) {n = i; break;}} |
---|
873 | return(n); |
---|
874 | } |
---|
875 | |
---|
876 | |
---|
877 | static proc isPF(intvec P, intvec I) |
---|
878 | " |
---|
879 | PURPOSE: |
---|
880 | checks, if a word P is a praefix of another word I |
---|
881 | " |
---|
882 | { |
---|
883 | int n = size(P); |
---|
884 | if (n <= 0 || P == 0) {return(1);} |
---|
885 | if (size(I) < n) {return(0);} |
---|
886 | intvec IP = I[1..n]; |
---|
887 | if (IP == P) {return(1);} |
---|
888 | else {return(0);} |
---|
889 | } |
---|
890 | |
---|
891 | static proc isSF(intvec S, intvec I) |
---|
892 | " |
---|
893 | PURPOSE: |
---|
894 | checks, if a word S is a suffix of another word I |
---|
895 | " |
---|
896 | { |
---|
897 | int n = size(S); |
---|
898 | if (n <= 0 || S == 0) {return(1);} |
---|
899 | int m = size(I); |
---|
900 | if (m < n) {return(0);} |
---|
901 | intvec IS = I[(m-n+1)..m]; |
---|
902 | if (IS == S) {return(1);} |
---|
903 | else {return(0);} |
---|
904 | } |
---|
905 | |
---|
906 | static proc isIF(intvec IF, intvec I) |
---|
907 | " |
---|
908 | PURPOSE: |
---|
909 | checks, if a word IF is an infix of another word I |
---|
910 | " |
---|
911 | { |
---|
912 | int n = size(IF); |
---|
913 | int m = size(I); |
---|
914 | |
---|
915 | if (n <= 0 || IF == 0) {return(1);} |
---|
916 | if (m < n) {return(0);} |
---|
917 | |
---|
918 | for (int i = 0; (n + i) <= m; i++){ |
---|
919 | intvec IIF = I[(1 + i)..(n + i)]; |
---|
920 | if (IIF == IF) { |
---|
921 | return(1); |
---|
922 | } |
---|
923 | } |
---|
924 | return(0); |
---|
925 | } |
---|
926 | |
---|
927 | proc ivL2lpI(list L) |
---|
928 | "USAGE: ivL2lpI(L); L a list of intvecs |
---|
929 | RETURN: ideal |
---|
930 | PURPOSE:Transforming a list of intvecs into an ideal of Letterplace monomials |
---|
931 | ASSUME: - Intvec corresponds to a Letterplace monomial |
---|
932 | @* - basering has to be a Letterplace ring |
---|
933 | EXAMPLE: example ivL2lpI; shows examples |
---|
934 | " |
---|
935 | {checkAssumptions(0,L); |
---|
936 | int i; ideal G; |
---|
937 | poly p; |
---|
938 | for (i = 1; i <= size(L); i++) |
---|
939 | {p = iv2lp(L[i]); |
---|
940 | G[(size(G) + 1)] = p; |
---|
941 | } |
---|
942 | return(G); |
---|
943 | } |
---|
944 | example |
---|
945 | { |
---|
946 | "EXAMPLE:"; echo = 2; |
---|
947 | ring r = 0,(x,y,z),dp; |
---|
948 | def R = makeLetterplaceRing(5);// constructs a Letterplace ring |
---|
949 | setring R; //sets basering to Letterplace ring |
---|
950 | intvec u = 1,1,2; intvec v = 2,1,3; intvec w = 3,1,1; |
---|
951 | // u = x^2y, v = yxz, w = zx^2 in intvec representation |
---|
952 | list L = u,v,w; |
---|
953 | ivL2lpI(L);// invokes the procedure, returns the ideal containing u,v,w |
---|
954 | } |
---|
955 | |
---|
956 | proc iv2lp(intvec I) |
---|
957 | "USAGE: iv2lp(I); I an intvec |
---|
958 | RETURN: poly |
---|
959 | PURPOSE:Transforming an intvec into the corresponding Letterplace polynomial |
---|
960 | ASSUME: - Intvec corresponds to a Letterplace monomial |
---|
961 | @* - basering has to be a Letterplace ring |
---|
962 | NOTE: - Assumptions will not be checked! |
---|
963 | EXAMPLE: example iv2lp; shows examples |
---|
964 | " |
---|
965 | {if (I[1] == 0) {return(1);} |
---|
966 | int i = size(I); |
---|
967 | if (i > attrib(basering,"uptodeg")) {ERROR("polynomial exceeds degreebound");} |
---|
968 | int j; poly p = 1; |
---|
969 | for (j = 1; j <= i; j++) {if (I[j] > 0) { p = lpMult(p,var(I[j]));}} //ignore zeroes, because they correspond to 1 |
---|
970 | return(p); |
---|
971 | } |
---|
972 | example |
---|
973 | { |
---|
974 | "EXAMPLE:"; echo = 2; |
---|
975 | ring r = 0,(x,y,z),dp; |
---|
976 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
977 | setring R; //sets basering to Letterplace ring |
---|
978 | intvec u = 1,1,2; intvec v = 2,1,3; intvec w = 3,1,1; |
---|
979 | // u = x^2y, v = yxz, w = zx^2 in intvec representation |
---|
980 | iv2lp(u); // invokes the procedure and returns the corresponding poly |
---|
981 | iv2lp(v); |
---|
982 | iv2lp(w); |
---|
983 | } |
---|
984 | |
---|
985 | proc iv2lpList(list L) |
---|
986 | "USAGE: iv2lpList(L); L a list of intmats |
---|
987 | RETURN: ideal |
---|
988 | PURPOSE:Converting a list of intmats into an ideal of corresponding monomials |
---|
989 | ASSUME: - The rows of each intmat in L must correspond to a Letterplace monomial |
---|
990 | @* - basering has to be a Letterplace ring |
---|
991 | EXAMPLE: example iv2lpList; shows examples |
---|
992 | " |
---|
993 | {checkAssumptions(0,L); |
---|
994 | ideal G; |
---|
995 | int i; |
---|
996 | for (i = 1; i <= size(L); i++){G = G + iv2lpMat(L[i]);} |
---|
997 | return(G); |
---|
998 | } |
---|
999 | example |
---|
1000 | { |
---|
1001 | "EXAMPLE:"; echo = 2; |
---|
1002 | ring r = 0,(x,y,z),dp; |
---|
1003 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
1004 | setring R; // sets basering to Letterplace ring |
---|
1005 | intmat u[3][1] = 1,1,2; intmat v[1][3] = 2,1,3; intmat w[2][3] = 3,1,1,2,3,1; |
---|
1006 | // defines intmats of different size containing intvec representations of |
---|
1007 | // monomials as rows |
---|
1008 | list L = u,v,w; |
---|
1009 | print(u); print(v); print(w); // shows the intmats contained in L |
---|
1010 | iv2lpList(L); // returns the corresponding monomials as an ideal |
---|
1011 | } |
---|
1012 | |
---|
1013 | |
---|
1014 | proc iv2lpMat(intmat M) |
---|
1015 | "USAGE: iv2lpMat(M); M an intmat |
---|
1016 | RETURN: ideal |
---|
1017 | PURPOSE:Converting an intmat into an ideal of the corresponding monomials |
---|
1018 | ASSUME: - The rows of M must correspond to Letterplace monomials |
---|
1019 | @* - basering has to be a Letterplace ring |
---|
1020 | EXAMPLE: example iv2lpMat; shows examples |
---|
1021 | " |
---|
1022 | {list L = M; |
---|
1023 | checkAssumptions(0,L); |
---|
1024 | kill L; |
---|
1025 | ideal G; poly p; |
---|
1026 | int i; intvec I; |
---|
1027 | for (i = 1; i <= nrows(M); i++) |
---|
1028 | { I = M[i,1..ncols(M)]; |
---|
1029 | p = iv2lp(I); |
---|
1030 | G[size(G)+1] = p; |
---|
1031 | } |
---|
1032 | return(G); |
---|
1033 | } |
---|
1034 | example |
---|
1035 | { |
---|
1036 | "EXAMPLE:"; echo = 2; |
---|
1037 | ring r = 0,(x,y,z),dp; |
---|
1038 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
1039 | setring R; // sets basering to Letterplace ring |
---|
1040 | intmat u[3][1] = 1,1,2; intmat v[1][3] = 2,1,3; intmat w[2][3] = 3,1,1,2,3,1; |
---|
1041 | // defines intmats of different size containing intvec representations of |
---|
1042 | // monomials as rows |
---|
1043 | iv2lpMat(u); // returns the monomials contained in u |
---|
1044 | iv2lpMat(v); // returns the monomials contained in v |
---|
1045 | iv2lpMat(w); // returns the monomials contained in w |
---|
1046 | } |
---|
1047 | |
---|
1048 | proc lpId2ivLi(ideal G) |
---|
1049 | "USAGE: lpId2ivLi(G); G an ideal |
---|
1050 | RETURN: list |
---|
1051 | PURPOSE:Transforming an ideal into the corresponding list of intvecs |
---|
1052 | ASSUME: - basering has to be a Letterplace ring |
---|
1053 | EXAMPLE: example lpId2ivLi; shows examples |
---|
1054 | " |
---|
1055 | { |
---|
1056 | int i,j,k; |
---|
1057 | list M; |
---|
1058 | checkAssumptions(0,M); |
---|
1059 | for (i = 1; i <= size(G); i++) {M[i] = lp2iv(G[i]);} |
---|
1060 | return(M); |
---|
1061 | } |
---|
1062 | example |
---|
1063 | { |
---|
1064 | "EXAMPLE:"; echo = 2; |
---|
1065 | ring r = 0,(x,y),dp; |
---|
1066 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
1067 | setring R; // sets basering to Letterplace ring |
---|
1068 | ideal L = x(1)*x(2),y(1)*y(2),x(1)*y(2)*x(3); |
---|
1069 | lpId2ivLi(L); // returns the corresponding intvecs as a list |
---|
1070 | } |
---|
1071 | |
---|
1072 | proc lp2iv(poly p) |
---|
1073 | "USAGE: lp2iv(p); p a poly |
---|
1074 | RETURN: intvec |
---|
1075 | PURPOSE:Transforming a monomial into the corresponding intvec |
---|
1076 | ASSUME: - basering has to be a Letterplace ring |
---|
1077 | NOTE: - Assumptions will not be checked! |
---|
1078 | EXAMPLE: example lp2iv; shows examples |
---|
1079 | " |
---|
1080 | {p = normalize(lead(p)); |
---|
1081 | intvec I; |
---|
1082 | int i,j; |
---|
1083 | if (deg(p) > attrib(basering,"uptodeg")) {ERROR("Monomial exceeds degreebound");} |
---|
1084 | if (p == 1) {return(I);} |
---|
1085 | if (p == 0) {ERROR("Monomial is not allowed to equal zero");} |
---|
1086 | intvec lep = leadexp(p); |
---|
1087 | for ( i = 1; i <= attrib(basering,"lV"); i++) {if (lep[i] == 1) {I = i; break;}} |
---|
1088 | for (i = (attrib(basering,"lV")+1); i <= size(lep); i++) |
---|
1089 | {if (lep[i] == 1) |
---|
1090 | { j = (i mod attrib(basering,"lV")); |
---|
1091 | if (j == 0) {I = I,attrib(basering,"lV");} |
---|
1092 | else {I = I,j;} |
---|
1093 | } |
---|
1094 | else { if (lep[i] > 1) {ERROR("monomial has a not allowed multidegree");}} |
---|
1095 | } |
---|
1096 | if (I[1] == 0) {ERROR("monomial has a not allowed multidegree");} |
---|
1097 | |
---|
1098 | return(I); |
---|
1099 | } |
---|
1100 | example |
---|
1101 | { |
---|
1102 | "EXAMPLE:"; echo = 2; |
---|
1103 | ring r = 0,(x,y,z),dp; |
---|
1104 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
1105 | setring R; // sets basering to Letterplace ring |
---|
1106 | poly p = x(1)*x(2)*z(3); poly q = y(1)*y(2)*x(3)*x(4); |
---|
1107 | poly w= z(1)*y(2)*x(3)*z(4)*z(5); |
---|
1108 | // p,q,w are some polynomials we want to transform into their |
---|
1109 | // intvec representation |
---|
1110 | lp2iv(p); lp2iv(q); lp2iv(w); |
---|
1111 | } |
---|
1112 | |
---|
1113 | proc lp2ivId(ideal G) |
---|
1114 | "USAGE: lp2ivId(G); G an ideal |
---|
1115 | RETURN: list |
---|
1116 | PURPOSE:Converting an ideal into an list of intmats, |
---|
1117 | @* the corresponding intvecs forming the rows |
---|
1118 | ASSUME: - basering has to be a Letterplace ring |
---|
1119 | EXAMPLE: example lp2ivId; shows examples |
---|
1120 | " |
---|
1121 | {G = normalize(lead(G)); |
---|
1122 | intvec I; list L; |
---|
1123 | checkAssumptions(0,L); |
---|
1124 | int i,md; |
---|
1125 | for (i = 1; i <= size(G); i++) { if (md <= deg(G[i])) {md = deg(G[i]);}} |
---|
1126 | while (size(G) > 0) |
---|
1127 | {ideal Gt; |
---|
1128 | for (i = 1; i <= ncols(G); i++) {if (md == deg(G[i])) {Gt = Gt + G[i]; G[i] = 0;}} |
---|
1129 | if (size(Gt) > 0) |
---|
1130 | {G = simplify(G,2); |
---|
1131 | intmat M [size(Gt)][md]; |
---|
1132 | for (i = 1; i <= size(Gt); i++) {M[i,1..md] = lp2iv(Gt[i]);} |
---|
1133 | L = insert(L,M); |
---|
1134 | kill M; kill Gt; |
---|
1135 | md = md - 1; |
---|
1136 | } |
---|
1137 | else {kill Gt; md = md - 1;} |
---|
1138 | } |
---|
1139 | return(L); |
---|
1140 | } |
---|
1141 | example |
---|
1142 | { |
---|
1143 | "EXAMPLE:"; echo = 2; |
---|
1144 | ring r = 0,(x,y,z),dp; |
---|
1145 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
1146 | setring R; // sets basering to Letterplace ring |
---|
1147 | poly p = x(1)*x(2)*z(3); poly q = y(1)*y(2)*x(3)*x(4); |
---|
1148 | poly w = z(1)*y(2)*x(3)*z(4); |
---|
1149 | // p,q,w are some polynomials we want to transform into their |
---|
1150 | // intvec representation |
---|
1151 | ideal G = p,q,w; |
---|
1152 | // define the ideal containing p,q and w |
---|
1153 | lp2ivId(G); // and return the list of intmats for this ideal |
---|
1154 | } |
---|
1155 | |
---|
1156 | // -----------------main procedures---------------------- |
---|
1157 | |
---|
1158 | proc lpNoetherian(ideal G) { |
---|
1159 | // return 0 not noetherian |
---|
1160 | // return 1 left |
---|
1161 | // return 2 right |
---|
1162 | // return 3 both |
---|
1163 | |
---|
1164 | G = lead(G); |
---|
1165 | G = simplify(G, 2+4+8); |
---|
1166 | |
---|
1167 | // check special case 1 |
---|
1168 | int l = 0; |
---|
1169 | for (int i = 1; i <= size(G); i++) { |
---|
1170 | // find the max degree in G |
---|
1171 | int d = deg(G[i]); |
---|
1172 | if (d > l) { |
---|
1173 | l = d; |
---|
1174 | } |
---|
1175 | |
---|
1176 | // also if G is the whole ring return noetherian |
---|
1177 | if (leadmonom(G[i]) == 1) { |
---|
1178 | return(3); |
---|
1179 | } |
---|
1180 | } |
---|
1181 | // if longest word has length 1 we handle it as a special case |
---|
1182 | if (l == 1) { |
---|
1183 | int n = attrib(basering, "lV"); // variable count |
---|
1184 | int k = size(G); |
---|
1185 | if (k == n) { // only the field left |
---|
1186 | return(3); // every field is noetherian |
---|
1187 | } |
---|
1188 | if (k == n-1) { // V = {1} with loop |
---|
1189 | return(3); |
---|
1190 | } |
---|
1191 | if (k <= n-2) { // V = {1} with more than one loop |
---|
1192 | return(0); |
---|
1193 | } |
---|
1194 | } |
---|
1195 | |
---|
1196 | intmat UG = lpUfGraph(G); |
---|
1197 | |
---|
1198 | // check special case 2 |
---|
1199 | intmat zero[nrows(UG)][ncols(UG)]; |
---|
1200 | if (UG == zero) { |
---|
1201 | return (3); |
---|
1202 | } |
---|
1203 | |
---|
1204 | if (!imHasLoops(UG) && imIsUpRightTriangle(topologicalSort(UG))) { |
---|
1205 | // UG is a DAG |
---|
1206 | return (3); |
---|
1207 | } |
---|
1208 | |
---|
1209 | // DFS from every vertex, if cycle is found, check every vertex for incomming/outcom |
---|
1210 | intvec visited; |
---|
1211 | visited[ncols(UG)] = 0; |
---|
1212 | int inFlag, outFlag; |
---|
1213 | for (int v = 1; v <= ncols(UG) && (inFlag + outFlag) != 3; v++) { |
---|
1214 | int inOutFlags = inOrOutCommingEdgeInCycle(UG, v, visited, 0); |
---|
1215 | if (inOutFlags == 1) { |
---|
1216 | inFlag = 1; |
---|
1217 | } |
---|
1218 | if (inOutFlags == 2) { |
---|
1219 | outFlag = 2; |
---|
1220 | } |
---|
1221 | if (inOutFlags == 3) { |
---|
1222 | inFlag = 1; |
---|
1223 | outFlag = 2; |
---|
1224 | } |
---|
1225 | } |
---|
1226 | return (3 - inFlag - outFlag); |
---|
1227 | } |
---|
1228 | |
---|
1229 | proc inOrOutCommingEdgeInCycle(intmat G, int v, intvec visited, intvec path) { |
---|
1230 | // Mark the current vertex as visited |
---|
1231 | visited[v] = 1; |
---|
1232 | |
---|
1233 | // Store the current vertex in path |
---|
1234 | if (path[1] == 0) { |
---|
1235 | path[1] = v; |
---|
1236 | } else { |
---|
1237 | path[size(path) + 1] = v; |
---|
1238 | } |
---|
1239 | |
---|
1240 | int inFlag, outFlag; |
---|
1241 | |
---|
1242 | for (int w = 1; w <= ncols(G) && (inFlag + outFlag) != 3; w++) { |
---|
1243 | if (G[v,w] == 1) { |
---|
1244 | if (visited[w] == 1) { |
---|
1245 | // new cycle |
---|
1246 | if (v == w) { |
---|
1247 | for (int u = 1; u <= ncols(G); u++) { |
---|
1248 | if (G[v,u] && u != v) { |
---|
1249 | outFlag = 2; |
---|
1250 | } |
---|
1251 | if (G[u,v] && u != v) { |
---|
1252 | inFlag = 1; |
---|
1253 | } |
---|
1254 | } |
---|
1255 | } else { |
---|
1256 | for (int i = size(path); i >= 1; i--) { // for each vertex in the path |
---|
1257 | // check for neighbors not directly next or prev in cycle |
---|
1258 | for (int u = 1; u <= ncols(G); u++) { |
---|
1259 | if (G[path[i],u] == 1) { // there is an edge to u |
---|
1260 | if (path[i] != v) { |
---|
1261 | if (u != path[i+1]) { // and u is not the next element in the cycle |
---|
1262 | outFlag = 2; |
---|
1263 | } |
---|
1264 | } else { |
---|
1265 | if (u != w) { |
---|
1266 | outFlag = 2; |
---|
1267 | } |
---|
1268 | } |
---|
1269 | } |
---|
1270 | if (G[u,path[i]] == 1) { // there is an edge from u |
---|
1271 | if (path[i] != w) { |
---|
1272 | if (u != path[i-1]) { // and u is not the previous element in the cylce |
---|
1273 | inFlag = 1; |
---|
1274 | } |
---|
1275 | } else { |
---|
1276 | if (u != v) { |
---|
1277 | inFlag = 1; |
---|
1278 | } |
---|
1279 | } |
---|
1280 | } |
---|
1281 | } |
---|
1282 | if (path[i] == w) { |
---|
1283 | break; |
---|
1284 | } |
---|
1285 | } |
---|
1286 | } |
---|
1287 | } else { |
---|
1288 | int inOutFlags = inOrOutCommingEdgeInCycle(G, w, visited, path); |
---|
1289 | if (inOutFlags == 1) { |
---|
1290 | inFlag = 1; |
---|
1291 | } |
---|
1292 | if (inOutFlags == 2) { |
---|
1293 | outFlag = 2; |
---|
1294 | } |
---|
1295 | if (inOutFlags == 3) { |
---|
1296 | inFlag = 1; |
---|
1297 | outFlag = 2; |
---|
1298 | } |
---|
1299 | } |
---|
1300 | } |
---|
1301 | } |
---|
1302 | |
---|
1303 | return (inFlag + outFlag); |
---|
1304 | } |
---|
1305 | |
---|
1306 | proc lpIsSemiPrime(ideal G) |
---|
1307 | { |
---|
1308 | G = lead(G); |
---|
1309 | G = simplify(G, 2+4+8); |
---|
1310 | |
---|
1311 | // check special case 1 |
---|
1312 | int l = 0; |
---|
1313 | for (int i = 1; i <= size(G); i++) { |
---|
1314 | // find the max degree in G |
---|
1315 | int d = deg(G[i]); |
---|
1316 | if (d > l) { |
---|
1317 | l = d; |
---|
1318 | } |
---|
1319 | |
---|
1320 | // also if G is the whole ring |
---|
1321 | if (leadmonom(G[i]) == 1) { |
---|
1322 | return(1); |
---|
1323 | } |
---|
1324 | } |
---|
1325 | // if longest word has length 1 we handle it as a special case |
---|
1326 | if (l == 1) { |
---|
1327 | return(1); |
---|
1328 | } |
---|
1329 | |
---|
1330 | list VUG = lpUfGraph(G, 1); |
---|
1331 | intmat UG = VUG[1]; // the Ufnarovskij graph |
---|
1332 | ideal V = VUG[2]; // the vertices of UG (standard words with length = l-1) |
---|
1333 | |
---|
1334 | list LG = lpId2ivLi(G); |
---|
1335 | list SW = ivStandardWordsUpToLength(LG, maxDeg(G)); |
---|
1336 | list LV = lpId2ivLi(V); |
---|
1337 | |
---|
1338 | // delete the 0 in SW |
---|
1339 | int indexofzero = ivIndexOf(SW, 0); |
---|
1340 | if (indexofzero > 0) { // should be always true when |SW| > 0 |
---|
1341 | SW = delete(SW, indexofzero); |
---|
1342 | } |
---|
1343 | |
---|
1344 | // check if each monomial in SW is cyclic |
---|
1345 | for (int i = 1; i <= size(SW); i++) { |
---|
1346 | if (!isCyclicInUfGraph(UG, LV, SW[i])) { |
---|
1347 | return (0); |
---|
1348 | } |
---|
1349 | } |
---|
1350 | |
---|
1351 | return (1); |
---|
1352 | } |
---|
1353 | |
---|
1354 | // checks whether a monomial is a cyclic monomial |
---|
1355 | proc isCyclicInUfGraph(intmat UG, list LV, intvec u) |
---|
1356 | { |
---|
1357 | if (ncols(UG) == 0) {return (0);} // UG is empty |
---|
1358 | if (u == 0) {return (0);} // 0 is never cyclic |
---|
1359 | |
---|
1360 | int l = size(LV[1]) + 1; |
---|
1361 | |
---|
1362 | int s = size(u); |
---|
1363 | if (s <= l - 1) { |
---|
1364 | for (int i = 1; i <= size(LV); i++) { |
---|
1365 | // for all vertices where u is a suffix |
---|
1366 | if(isSF(u, LV[i])) { |
---|
1367 | if (existsRoute(UG, i, i)) { |
---|
1368 | return (1); |
---|
1369 | } |
---|
1370 | } |
---|
1371 | } |
---|
1372 | } else { // size(u) > l - 1 |
---|
1373 | int m = s - l + 1; |
---|
1374 | |
---|
1375 | // there must be a route from v0 to vm |
---|
1376 | intvec v0 = u[1..(l-1)]; // first in route of u |
---|
1377 | intvec vm = u[m+1..m+(l-1)]; // last in route of u |
---|
1378 | |
---|
1379 | int iv0 = ivIndexOf(LV, v0); |
---|
1380 | int ivm = ivIndexOf(LV, vm); |
---|
1381 | if (iv0 <= 0 || ivm <= 0) { |
---|
1382 | ERROR("u is not a standard word"); |
---|
1383 | } |
---|
1384 | |
---|
1385 | return (existsRoute(UG, ivm, iv0)); |
---|
1386 | } |
---|
1387 | |
---|
1388 | return (0); |
---|
1389 | } |
---|
1390 | |
---|
1391 | proc lpIsPrime(ideal G) |
---|
1392 | "USAGE: lpIsPrime(G); G an ideal in a Letterplace ring |
---|
1393 | RETURN: boolean |
---|
1394 | PURPOSE: Check whether R/<G> is prime, where R is the basering |
---|
1395 | ASSUME: - basering is a Letterplace ring |
---|
1396 | @* - G is a Groebner basis |
---|
1397 | " |
---|
1398 | { |
---|
1399 | G = lead(G); |
---|
1400 | G = simplify(G, 2+4+8); |
---|
1401 | |
---|
1402 | // check special case 1 |
---|
1403 | int l = 0; |
---|
1404 | for (int i = 1; i <= size(G); i++) { |
---|
1405 | // find the max degree in G |
---|
1406 | int d = deg(G[i]); |
---|
1407 | if (d > l) { |
---|
1408 | l = d; |
---|
1409 | } |
---|
1410 | |
---|
1411 | // also if G is the whole ring |
---|
1412 | if (leadmonom(G[i]) == 1) { |
---|
1413 | return(1); |
---|
1414 | } |
---|
1415 | } |
---|
1416 | // if longest word has length 1 we handle it as a special case |
---|
1417 | if (l == 1) { |
---|
1418 | return(1); |
---|
1419 | } |
---|
1420 | |
---|
1421 | list VUG = lpUfGraph(G, 1); |
---|
1422 | intmat UG = VUG[1]; // the Ufnarovskij graph |
---|
1423 | ideal V = VUG[2]; // the vertices of UG (standard words with length = l-1) |
---|
1424 | |
---|
1425 | list LG = lpId2ivLi(G); |
---|
1426 | list LV = lpId2ivLi(V); |
---|
1427 | |
---|
1428 | int n = ncols(UG); |
---|
1429 | |
---|
1430 | // 1) for each vi vj there exists a route from vi to vj (means UG is connected) |
---|
1431 | for (int i = 1; i <= n; i++) { |
---|
1432 | for (int j = 1; j <= n; j++) { |
---|
1433 | if (!existsRoute(UG, i, j)) { |
---|
1434 | return (0); |
---|
1435 | } |
---|
1436 | } |
---|
1437 | } |
---|
1438 | |
---|
1439 | // 2) any standard word with length < l-1 is a suffix of a vertex |
---|
1440 | list SW = ivStandardWordsUpToLength(LG, maxDeg(G) - 2); // < maxDeg - 1 |
---|
1441 | if (size(SW) > 0 && size(LV) == 0) {return (0);} |
---|
1442 | for (int i = 1; i <= size(SW); i++) { |
---|
1443 | // check if SW[i] is a suffix of some LV |
---|
1444 | for (int j = 1; j <= size(LV); j++) { |
---|
1445 | if (!isSF(SW[i], LV[j])) { |
---|
1446 | if (j == size(LV)) { |
---|
1447 | return (0); |
---|
1448 | } |
---|
1449 | } else { |
---|
1450 | break; |
---|
1451 | } |
---|
1452 | } |
---|
1453 | } |
---|
1454 | |
---|
1455 | return (1); |
---|
1456 | } |
---|
1457 | example { |
---|
1458 | "EXAMPLE:"; echo = 2; |
---|
1459 | ring r = 0,(x,y),dp; |
---|
1460 | def R = makeLetterplaceRing(5); |
---|
1461 | setring R; |
---|
1462 | ideal G = x(1)*x(2), y(1)*y(2); // K<x,y>/<xx,yy> is prime |
---|
1463 | lpIsPrime(G); |
---|
1464 | } |
---|
1465 | |
---|
1466 | static proc existsRoute(intmat G, int v, int u, list #) |
---|
1467 | "USAGE: existsRoute(G,v,u); G a graph, v and u vertices |
---|
1468 | NOTE: don't pass anything to # (internal use for recursion) |
---|
1469 | @* routes always have at least one edge |
---|
1470 | " |
---|
1471 | { |
---|
1472 | int n = ncols(G); |
---|
1473 | |
---|
1474 | // init visited |
---|
1475 | intvec visited; |
---|
1476 | if (size(#) > 0) { |
---|
1477 | if (v == u) {return (1);} // don't check on first call so |route| >= 1 holds |
---|
1478 | visited = #[1]; |
---|
1479 | } else { // first call |
---|
1480 | visited[n] = 0; |
---|
1481 | } |
---|
1482 | |
---|
1483 | // mark current vertex as visited |
---|
1484 | visited[v] = 1; |
---|
1485 | |
---|
1486 | // recursive DFS |
---|
1487 | for (int i = 1; i <= n; i++) { |
---|
1488 | if (G[v,i] && (!visited[i] || i == u)) { // i == u to allow routes from u to u |
---|
1489 | if (existsRoute(G, i, u, visited)) { |
---|
1490 | return (1); |
---|
1491 | } |
---|
1492 | } |
---|
1493 | } |
---|
1494 | |
---|
1495 | return (0); |
---|
1496 | } |
---|
1497 | |
---|
1498 | static proc lpUfGkDim(ideal G) |
---|
1499 | { |
---|
1500 | G = lead(G); |
---|
1501 | G = simplify(G, 2+4+8); |
---|
1502 | |
---|
1503 | // check special case 1 |
---|
1504 | int l = 0; |
---|
1505 | for (int i = 1; i <= size(G); i++) { |
---|
1506 | // find the max degree in G |
---|
1507 | int d = deg(G[i]); |
---|
1508 | if (d > l) { |
---|
1509 | l = d; |
---|
1510 | } |
---|
1511 | |
---|
1512 | // also if G is the whole ring return minus infinity |
---|
1513 | if (leadmonom(G[i]) == 1) { |
---|
1514 | return(-2); // minus infinity |
---|
1515 | } |
---|
1516 | } |
---|
1517 | // if longest word has length 1 we handle it as a special case |
---|
1518 | if (l == 1) { |
---|
1519 | int n = attrib(basering, "lV"); // variable count |
---|
1520 | int k = size(G); |
---|
1521 | if (k == n) { // V = {1} no edges |
---|
1522 | return(0); |
---|
1523 | } |
---|
1524 | if (k == n-1) { // V = {1} with loop |
---|
1525 | return(1); |
---|
1526 | } |
---|
1527 | if (k <= n-2) { // V = {1} with more than one loop |
---|
1528 | return(-1); |
---|
1529 | } |
---|
1530 | } |
---|
1531 | |
---|
1532 | int t = rtimer; // DEBUG |
---|
1533 | intmat UG = lpUfGraph(G); |
---|
1534 | printf("lpUfGraph took %p", rtimer - t); // DEBUG |
---|
1535 | |
---|
1536 | // check special case 2 |
---|
1537 | intmat zero[nrows(UG)][ncols(UG)]; |
---|
1538 | if (UG == zero) { |
---|
1539 | return (0); |
---|
1540 | } |
---|
1541 | |
---|
1542 | // check special case 3 |
---|
1543 | UG = topologicalSort(UG); |
---|
1544 | |
---|
1545 | if (imIsUpRightTriangle(UG)) { |
---|
1546 | UG = eliminateZerosUpTriangle(UG); |
---|
1547 | if (ncols(UG) == 0 || nrows(UG) == 0) { // when the diagonal was zero |
---|
1548 | return (0) |
---|
1549 | } |
---|
1550 | return(UfGraphURTNZDGrowth(UG)); |
---|
1551 | } |
---|
1552 | |
---|
1553 | // otherwise count cycles in the Ufnarovskij Graph |
---|
1554 | int t = rtimer; // DEBUG |
---|
1555 | int gkdim = UfGraphGrowth(UG); |
---|
1556 | printf("UfGraphGrowth took %p", rtimer - t); // DEBUG |
---|
1557 | return(gkdim); |
---|
1558 | } |
---|
1559 | |
---|
1560 | static proc UfGraphURTNZDGrowth(intmat UG) { |
---|
1561 | // URTNZD = upper right triangle non zero diagonal |
---|
1562 | for (int i = 1; i <= ncols(UG); i++) { |
---|
1563 | UG[i,i] = 0; // remove all loops |
---|
1564 | } |
---|
1565 | intmat UGk = UG; |
---|
1566 | intmat zero[nrows(UGk)][ncols(UGk)]; |
---|
1567 | int k = 1; |
---|
1568 | while (UGk != zero) { |
---|
1569 | UGk = UGk * UG; |
---|
1570 | k++; |
---|
1571 | } |
---|
1572 | return (k); |
---|
1573 | } |
---|
1574 | |
---|
1575 | proc imIsUpRightTriangle(intmat M) { |
---|
1576 | for (int i = 1; i <= nrows(M); i++) { |
---|
1577 | for (int j = 1; j < i; j++) { |
---|
1578 | if(M[i,j] != 0) { return (0); } |
---|
1579 | } |
---|
1580 | } |
---|
1581 | return (1); |
---|
1582 | } |
---|
1583 | |
---|
1584 | static proc eliminateZerosUpTriangle(intmat G) { |
---|
1585 | // G is expected to be an upper triangle matrix |
---|
1586 | for (int i = ncols(G); i >= 1; i--) { // loop order is important because we delete entries |
---|
1587 | if (G[i,i] == 0) { // i doesn't have a cycle |
---|
1588 | for (int j = 1; j < i; j++) { |
---|
1589 | if (G[j,i] == 1) { // j has an edge to i |
---|
1590 | for (int k = i + 1; k <= nrows(G); k++) { |
---|
1591 | if (G[i,k] == 1) { |
---|
1592 | G[j,k] = G[i,k]; // give j all edges from i |
---|
1593 | } |
---|
1594 | } |
---|
1595 | } |
---|
1596 | } |
---|
1597 | G = imDelRowCol(G,i,i); // remove vertex i |
---|
1598 | } |
---|
1599 | } |
---|
1600 | return (G); |
---|
1601 | } |
---|
1602 | |
---|
1603 | static proc imDelRowCol(intmat M, int row, int col) { |
---|
1604 | // row and col are expected to be > 0 |
---|
1605 | int nr = nrows(M); |
---|
1606 | int nc = ncols(M); |
---|
1607 | intmat Mdel[nr - 1][nc - 1]; |
---|
1608 | for (int i = 1; i <= nr; i++) { |
---|
1609 | for (int j = 1; j <= nc; j++) { |
---|
1610 | if(i != row && j != col) { |
---|
1611 | int newi = i; |
---|
1612 | int newj = j; |
---|
1613 | if (i > row) { newi = i - 1; } |
---|
1614 | if (j > col) { newj = j - 1; } |
---|
1615 | Mdel[newi,newj] = M[i,j]; |
---|
1616 | } |
---|
1617 | } |
---|
1618 | } |
---|
1619 | return (Mdel); |
---|
1620 | } |
---|
1621 | |
---|
1622 | static proc topologicalSort(intmat G) { |
---|
1623 | // NOTE: ignores loops |
---|
1624 | // NOTE: this takes O(|V^3|), can be optimized |
---|
1625 | int n = ncols(G); |
---|
1626 | for (int i = 1; i <= n; i++) { // only use the submat at i |
---|
1627 | // find a vertex v in the submat at i with no incoming edges |
---|
1628 | int v; |
---|
1629 | for (int j = i; j <= n; j++) { |
---|
1630 | int incoming = 0; |
---|
1631 | for (int k = i; k <= n; k++) { |
---|
1632 | if (k != j && G[k,j] == 1) { |
---|
1633 | incoming = 1; |
---|
1634 | } |
---|
1635 | } |
---|
1636 | if (incoming == 0) { |
---|
1637 | v = j; |
---|
1638 | break; |
---|
1639 | } else { |
---|
1640 | if (j == n) { |
---|
1641 | // G contains at least one cycle, abort |
---|
1642 | return (G); |
---|
1643 | } |
---|
1644 | } |
---|
1645 | } |
---|
1646 | |
---|
1647 | // swap v and i |
---|
1648 | if (v != i) { |
---|
1649 | G = imPermcol(G, v, i); |
---|
1650 | G = imPermrow(G, v, i); |
---|
1651 | } |
---|
1652 | } |
---|
1653 | return (G); |
---|
1654 | } |
---|
1655 | |
---|
1656 | static proc imPermcol (intmat A, int c1, int c2) |
---|
1657 | { |
---|
1658 | intmat B = A; |
---|
1659 | int k = nrows(B); |
---|
1660 | B[1..k,c1] = A[1..k,c2]; |
---|
1661 | B[1..k,c2] = A[1..k,c1]; |
---|
1662 | return (B); |
---|
1663 | } |
---|
1664 | |
---|
1665 | static proc imPermrow (intmat A, int r1, int r2) |
---|
1666 | { |
---|
1667 | intmat B = A; |
---|
1668 | int k = ncols(B); |
---|
1669 | B[r1,1..k] = A[r2,1..k]; |
---|
1670 | B[r2,1..k] = A[r1,1..k]; |
---|
1671 | return (B); |
---|
1672 | } |
---|
1673 | |
---|
1674 | static proc UfGraphGrowth(intmat UG) |
---|
1675 | { |
---|
1676 | int n = ncols(UG); // number of vertices |
---|
1677 | // iterate through all vertices |
---|
1678 | |
---|
1679 | intvec visited; |
---|
1680 | visited[n] = 0; |
---|
1681 | |
---|
1682 | intvec cyclic; |
---|
1683 | cyclic[n] = 0; |
---|
1684 | |
---|
1685 | int maxCycleCount = 0; |
---|
1686 | for (int v = 1; v <= n; v++) { |
---|
1687 | int cycleCount = countCycles(UG, v, visited, cyclic, 0); |
---|
1688 | if (cycleCount == -1) { |
---|
1689 | return(-1); |
---|
1690 | } |
---|
1691 | if (cycleCount > maxCycleCount) { |
---|
1692 | maxCycleCount = cycleCount; |
---|
1693 | } |
---|
1694 | } |
---|
1695 | return(maxCycleCount); |
---|
1696 | } |
---|
1697 | |
---|
1698 | static proc countCycles(intmat G, int v, intvec visited, intvec cyclic, intvec path) |
---|
1699 | "USAGE: countCycles(G, v, visited, cyclic, path); G a Graph, v the vertex to |
---|
1700 | start. The parameter visited, cyclic and path should be 0. |
---|
1701 | RETURN: int |
---|
1702 | @*: Maximal number of distinct cycles |
---|
1703 | PURPOSE: Calculate the maximal number of distinct cycles in a single path starting at v |
---|
1704 | ASSUME: Basering is a Letterplace ring |
---|
1705 | " |
---|
1706 | { |
---|
1707 | // Mark the current vertex as visited |
---|
1708 | visited[v] = 1; |
---|
1709 | |
---|
1710 | // Store the current vertex in path |
---|
1711 | if (path[1] == 0) { |
---|
1712 | path[1] = v; |
---|
1713 | } else { |
---|
1714 | path[size(path) + 1] = v; |
---|
1715 | } |
---|
1716 | |
---|
1717 | int cycles = 0; |
---|
1718 | for (int w = 1; w <= ncols(G); w++) { |
---|
1719 | if (G[v,w] == 1) { |
---|
1720 | if (visited[w] == 1) { // neuer zykel gefunden |
---|
1721 | // 1. alle Knoten in path bis w ÃŒberprÃŒfen ob in cyclic |
---|
1722 | for (int j = size(path); j >= 1; j--) { |
---|
1723 | if(cyclic[path[j]] == 1) { |
---|
1724 | // 1.1 falls ja return -1 |
---|
1725 | return (-1); |
---|
1726 | } |
---|
1727 | if (path[j] == w) { |
---|
1728 | break; |
---|
1729 | } |
---|
1730 | } |
---|
1731 | |
---|
1732 | // 2. ansonsten cycles++ |
---|
1733 | for (int j = size(path); j >= 1; j--) { |
---|
1734 | // 2.2 Kanten in diesem Zykel entfernen; Knoten cyclic |
---|
1735 | if (j == size(path)) { // Sonderfall bei der ersten Iteration |
---|
1736 | cyclic[v] = 1; |
---|
1737 | G[v, w] = 0; |
---|
1738 | } else { |
---|
1739 | cyclic[path[j]] = 1; |
---|
1740 | G[path[j], path[j+1]] = 0; |
---|
1741 | } |
---|
1742 | if (path[j] == w) { |
---|
1743 | break; |
---|
1744 | } |
---|
1745 | } |
---|
1746 | |
---|
1747 | // 3. auf jedem dieser Knoten countCycles() aufrufen |
---|
1748 | int maxCycleCount = 0; |
---|
1749 | for (int j = size(path); j >= 1; j--) { |
---|
1750 | int cycleCount = countCycles(G, path[j], visited, cyclic, path); |
---|
1751 | if(cycleCount == -1) { |
---|
1752 | return (-1); |
---|
1753 | } |
---|
1754 | if (cycleCount > maxCycleCount) { |
---|
1755 | maxCycleCount = cycleCount; |
---|
1756 | } |
---|
1757 | if (path[j] == w) { |
---|
1758 | break; |
---|
1759 | } |
---|
1760 | } |
---|
1761 | if (maxCycleCount >= cycles) { |
---|
1762 | cycles = maxCycleCount + 1; |
---|
1763 | } |
---|
1764 | } else { |
---|
1765 | int cycleCount = countCycles(G, w, visited, cyclic, path); |
---|
1766 | if (cycleCount == -1) { |
---|
1767 | return(-1); |
---|
1768 | } |
---|
1769 | if (cycleCount > cycles) { |
---|
1770 | cycles = cycleCount; |
---|
1771 | } |
---|
1772 | } |
---|
1773 | } |
---|
1774 | } |
---|
1775 | // printf("Path: %s countCycles: %s", path, cycles); // DEBUG |
---|
1776 | return(cycles); |
---|
1777 | } |
---|
1778 | |
---|
1779 | static proc lpUfGraph(ideal G, list #) |
---|
1780 | "USAGE: lpUfGraph(G); G a set of monomials in a letterplace ring, # an optional parameter to return the vertex list when set |
---|
1781 | RETURN: intmat |
---|
1782 | PURPOSE: Constructs the Ufnarovskij graph induced by G |
---|
1783 | @* the adjacency matrix of the Ufnarovskij graph induced by G |
---|
1784 | ASSUME: - basering is a Letterplace ring |
---|
1785 | @* - G are the leading monomials of a Groebner basis |
---|
1786 | " |
---|
1787 | { |
---|
1788 | int l = maxDeg(G); |
---|
1789 | list LG = lpId2ivLi(G); |
---|
1790 | list SW = ivStandardWords(LG, l - 1); // vertices |
---|
1791 | int n = size(SW); |
---|
1792 | intmat UG[n][n]; // Ufnarovskij graph |
---|
1793 | for (int i = 1; i <= n; i++) { |
---|
1794 | for (int j = 1; j <= n; j++) { |
---|
1795 | // [Studzinski page 76] |
---|
1796 | intvec v = SW[i]; |
---|
1797 | intvec w = SW[j]; |
---|
1798 | intvec v_overlap; |
---|
1799 | intvec w_overlap; |
---|
1800 | //TODO how should the graph look like when l - 1 = 0 ? |
---|
1801 | if (l - 1 == 0) { |
---|
1802 | ERROR("Ufnarovskij graph not implemented for l = 1"); |
---|
1803 | } |
---|
1804 | if (l - 1 > 1) { |
---|
1805 | v_overlap = v[2 .. l-1]; |
---|
1806 | w_overlap = w[1 .. l-2]; |
---|
1807 | } |
---|
1808 | intvec vw = v; |
---|
1809 | vw[l] = w[l-1]; |
---|
1810 | if (v_overlap == w_overlap && !ivdivides(LG, vw)) { |
---|
1811 | UG[i,j] = 1; |
---|
1812 | } |
---|
1813 | } |
---|
1814 | } |
---|
1815 | if (size(#) > 0) { |
---|
1816 | if (typeof(#[1]) == "int") { |
---|
1817 | if (#[1] == 1) { |
---|
1818 | list ret = UG; |
---|
1819 | ret[2] = ivL2lpI(SW); // the vertices |
---|
1820 | return (ret); |
---|
1821 | } |
---|
1822 | } |
---|
1823 | } |
---|
1824 | return (UG); |
---|
1825 | } |
---|
1826 | |
---|
1827 | static proc maxDeg(ideal G) |
---|
1828 | { |
---|
1829 | int l = 0; |
---|
1830 | for (int i = 1; i <= size(G); i++) { // find the max degree in G |
---|
1831 | int d = deg(G[i]); |
---|
1832 | if (d > l) { |
---|
1833 | l = d; |
---|
1834 | } |
---|
1835 | } |
---|
1836 | return (l); |
---|
1837 | } |
---|
1838 | |
---|
1839 | static proc ivStandardWords(list G, int length) |
---|
1840 | "ASSUME: G is simplified |
---|
1841 | " |
---|
1842 | { |
---|
1843 | if (length <= 0) { |
---|
1844 | list words; |
---|
1845 | if (length == 0 && !ivdivides(G,0)) { |
---|
1846 | words[1] = 0; // iv = 0 means monom = 1 |
---|
1847 | } |
---|
1848 | return (words); // no standard words |
---|
1849 | } |
---|
1850 | int lV = attrib(basering, "lV"); // variable count |
---|
1851 | list prevWords = ivStandardWords(G, length - 1); |
---|
1852 | list words; |
---|
1853 | for (int i = 1; i <= lV; i++) { |
---|
1854 | for (int j = 1; j <= size(prevWords); j++) { |
---|
1855 | intvec word = prevWords[j]; |
---|
1856 | word[length] = i; |
---|
1857 | // assumes that G is simplified! |
---|
1858 | if (!ivdivides(G, word)) { |
---|
1859 | words = insert(words, word); |
---|
1860 | } |
---|
1861 | } |
---|
1862 | } |
---|
1863 | return (words); |
---|
1864 | } |
---|
1865 | |
---|
1866 | static proc ivStandardWordsUpToLength(list G, int length) |
---|
1867 | "ASSUME: G is simplified |
---|
1868 | " |
---|
1869 | { |
---|
1870 | list words = ivStandardWords(G,0); |
---|
1871 | if (size(words) == 0) {return (words)} |
---|
1872 | for (int i = 1; i <= length; i++) { |
---|
1873 | words = words + ivStandardWords(G, i); |
---|
1874 | } |
---|
1875 | return (words); |
---|
1876 | } |
---|
1877 | |
---|
1878 | static proc ivdivides(list G, intvec iv) { |
---|
1879 | for (int k = 1; k <= size(G); k++) { |
---|
1880 | if (isIF(G[k], iv)) { |
---|
1881 | return (1); |
---|
1882 | } else { |
---|
1883 | if (k == size(G)) { |
---|
1884 | return (0); |
---|
1885 | } |
---|
1886 | } |
---|
1887 | } |
---|
1888 | } |
---|
1889 | |
---|
1890 | static proc lpGraphOfNormalWords(ideal G) |
---|
1891 | "USAGE: lpGraphOfNormalWords(G); G a set of monomials in a letterplace ring |
---|
1892 | RETURN: intmat |
---|
1893 | PURPOSE: Constructs the graph of normal words induced by G |
---|
1894 | @*: the adjacency matrix of the graph of normal words induced by G |
---|
1895 | ASSUME: - basering is a Letterplace ring |
---|
1896 | - G are the leading monomials of a Groebner basis |
---|
1897 | " |
---|
1898 | { |
---|
1899 | // construct the Graph of normal words [Studzinski page 78] |
---|
1900 | // construct set of vertices |
---|
1901 | int v = attrib(basering,"lV"); int d = attrib(basering,"uptodeg"); |
---|
1902 | ideal V; poly p,q,w; |
---|
1903 | ideal LG = lead(G); |
---|
1904 | int i,j,k,b; intvec E,Et; |
---|
1905 | for (i = 1; i <= v; i++){V = V, var(i);} |
---|
1906 | for (i = 1; i <= size(LG); i++) |
---|
1907 | { |
---|
1908 | E = leadexp(LG[i]); |
---|
1909 | if (E == intvec(0)) {V = V,monomial(intvec(0));} |
---|
1910 | else |
---|
1911 | { |
---|
1912 | for (j = 1; j < d; j++) |
---|
1913 | { |
---|
1914 | Et = E[(j*v+1)..(d*v)]; |
---|
1915 | if (Et == intvec(0)) {break;} |
---|
1916 | else {V = V, monomial(Et);} |
---|
1917 | } |
---|
1918 | } |
---|
1919 | } |
---|
1920 | V = simplify(V,2+4); |
---|
1921 | printf("V = %p", V); |
---|
1922 | |
---|
1923 | |
---|
1924 | // construct incidence matrix |
---|
1925 | |
---|
1926 | list LV = lpId2ivLi(V); |
---|
1927 | intvec Ip,Iw; |
---|
1928 | int n = size(V); |
---|
1929 | intmat T[n+1][n]; |
---|
1930 | for (i = 1; i <= n; i++) |
---|
1931 | { |
---|
1932 | // printf("for1 (i=%p, n=%p)", i, n); |
---|
1933 | p = V[i]; Ip = lp2iv(p); |
---|
1934 | for (j = 1; j <= n; j++) |
---|
1935 | { |
---|
1936 | // printf("for2 (j=%p, n=%p)", j, n); |
---|
1937 | k = 1; b = 1; |
---|
1938 | q = V[j]; |
---|
1939 | w = lpNF(lpMult(p,q),LG); |
---|
1940 | if (w <> 0) |
---|
1941 | { |
---|
1942 | Iw = lp2iv(w); |
---|
1943 | while (k <= n) |
---|
1944 | { |
---|
1945 | // printf("while (k=%p, n=%p)", k, n); |
---|
1946 | if (isPF(LV[k],Iw) > 0) |
---|
1947 | {if (isPF(LV[k],Ip) == 0) {b = 0; k = n+1;} else {k++;} |
---|
1948 | } |
---|
1949 | else {k++;} |
---|
1950 | } |
---|
1951 | T[i,j] = b; |
---|
1952 | // print("Incidence Matrix:"); |
---|
1953 | // print(T); |
---|
1954 | } |
---|
1955 | } |
---|
1956 | } |
---|
1957 | return(T); |
---|
1958 | } |
---|
1959 | |
---|
1960 | static proc lpNorGkDim(ideal G) |
---|
1961 | "USAGE: lpNorGkDim(G); G an ideal in a letterplace ring |
---|
1962 | RETURN: int |
---|
1963 | PURPOSE: Determines the Gelfand Kirillov dimension of A/<G> |
---|
1964 | @*: -1 means it is infinite |
---|
1965 | ASSUME: - basering is a Letterplace ring |
---|
1966 | - G is a Groebner basis |
---|
1967 | " |
---|
1968 | { |
---|
1969 | return(growthAlg(lpGraphOfNormalWords(G))); |
---|
1970 | } |
---|
1971 | |
---|
1972 | proc lpGkDim(ideal G, list#) |
---|
1973 | "USAGE: lpGkDim(G); G an ideal in a letterplace ring, method an |
---|
1974 | @* optional integer. method = 0 uses the Ufnarovskij Graph |
---|
1975 | @* and method = 1 uses the Graph of normal words to determine |
---|
1976 | @* the Gelfand Kirillov dimension |
---|
1977 | RETURN: int |
---|
1978 | PURPOSE: Determines the Gelfand Kirillov dimension of A/<G> |
---|
1979 | @* -1 means it is positive infinite |
---|
1980 | @* -2 means it is negative infinite |
---|
1981 | ASSUME: - basering is a Letterplace ring |
---|
1982 | - G is a Groebner basis |
---|
1983 | " |
---|
1984 | { |
---|
1985 | int method = 0; |
---|
1986 | if (size(#) > 0) { |
---|
1987 | if (typeof(#[1])=="int") { |
---|
1988 | method = #[1]; |
---|
1989 | } |
---|
1990 | } |
---|
1991 | |
---|
1992 | if (method == 0) { |
---|
1993 | return (lpUfGkDim(G)); |
---|
1994 | } else { |
---|
1995 | return (lpNorGkDim(G)); |
---|
1996 | } |
---|
1997 | } |
---|
1998 | example |
---|
1999 | { |
---|
2000 | "EXAMPLE:"; echo = 2; |
---|
2001 | ring r = 0,(x,y,z),dp; |
---|
2002 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2003 | R; |
---|
2004 | setring R; // sets basering to Letterplace ring |
---|
2005 | ideal I = z(1);//an example of infinite GK dimension |
---|
2006 | lpGkDim(I); |
---|
2007 | I = x(1),y(1),z(1); // gkDim = 0 |
---|
2008 | lpGkDim(I); |
---|
2009 | I = x(1)*y(2), x(1)*z(2), z(1)*y(2), z(1)*z(2);//gkDim = 2 |
---|
2010 | lpGkDim(I); |
---|
2011 | } |
---|
2012 | |
---|
2013 | proc lpGlDimBound(ideal G) |
---|
2014 | "USAGE: lpGlDimBound(I); I an ideal |
---|
2015 | RETURN: int, an upper bound for the global dimension, -1 means infinity |
---|
2016 | PURPOSE: computing an upper bound for the global dimension |
---|
2017 | ASSUME: - basering is a Letterplace ring, G is a reduced Gröbner Basis |
---|
2018 | EXAMPLE: example lpGlDimBound; shows example |
---|
2019 | NOTE: if I = LM(I), then the global dimension is equal the Gelfand |
---|
2020 | @* Kirillov dimension if it is finite |
---|
2021 | @* Global dimension should be 0 for A/G = K and 1 for A/G = K<x1...xn> |
---|
2022 | " |
---|
2023 | { |
---|
2024 | G = simplify(G,2); // remove zero generators |
---|
2025 | // NOTE: Gl should be 0 for A/G = K and 1 for A/G = K<x1...xn> |
---|
2026 | // G1 contains generators with single variable in LM |
---|
2027 | ideal G1; |
---|
2028 | for (int i = 1; i <= size(G); i++) { |
---|
2029 | if (ord(G[i]) < 2) { // single variable in LM |
---|
2030 | G1 = insertGenerator(G1,G[i]); |
---|
2031 | } |
---|
2032 | } |
---|
2033 | G1 = simplify(G1,2); // remove zero generators |
---|
2034 | |
---|
2035 | // G = NF(G,G1) |
---|
2036 | for (int i = 1; i <= ncols(G); i++) { // do not use size() here |
---|
2037 | G[i] = lpNF(G[i],G1); |
---|
2038 | } |
---|
2039 | G = simplify(G,2); // remove zero generators |
---|
2040 | |
---|
2041 | // delete variables in LM(G1) from the ring |
---|
2042 | def save = basering; |
---|
2043 | ring R = basering; |
---|
2044 | if (size(G1) > 0) { |
---|
2045 | while (size(G1) > 0) { |
---|
2046 | if (attrib(R, "lV") > 1) { |
---|
2047 | ring R = lpDelVar(lp2iv(G1[1])[1]); |
---|
2048 | ideal G1 = imap(save,G1); |
---|
2049 | G1 = simplify(G1, 2); // remove zero generators |
---|
2050 | } else { |
---|
2051 | // only the field is left (no variables) |
---|
2052 | return(0); |
---|
2053 | } |
---|
2054 | } |
---|
2055 | ideal G = imap(save, G); // put this here, because when save == R this call would make G = 0 |
---|
2056 | } |
---|
2057 | |
---|
2058 | // Li p. 184 if G = LM(G), then I = LM(I) and thus glDim = gkDim if it's finite |
---|
2059 | for (int i = 1; i <= size(G); i++) { |
---|
2060 | if (G[i] != lead(G[i])) { |
---|
2061 | break; |
---|
2062 | } else { |
---|
2063 | if (i == size(G)) { // if last iteration |
---|
2064 | print("Using gk dim"); // DEBUG |
---|
2065 | int gkDim = lpGkDim(G); |
---|
2066 | if (gkDim >= 0) { |
---|
2067 | return (gkDim); |
---|
2068 | } |
---|
2069 | } |
---|
2070 | } |
---|
2071 | } |
---|
2072 | |
---|
2073 | intmat GNC = lpGraphOfNChains(G); |
---|
2074 | |
---|
2075 | // assuming GNC is connected |
---|
2076 | |
---|
2077 | // TODO: maybe loop+cycle checking could be done more efficiently? |
---|
2078 | if (!imHasLoops(GNC) && imIsUpRightTriangle(topologicalSort(GNC))) { |
---|
2079 | // GNC is a DAG |
---|
2080 | intmat GNCk = GNC; |
---|
2081 | intmat zero[1][ncols(GNCk)]; |
---|
2082 | int k = 1; |
---|
2083 | // while first row isn't empty |
---|
2084 | while (GNCk[1,1..(ncols(GNCk))] != zero[1,1..(ncols(zero))]) { |
---|
2085 | GNCk = GNCk * GNC; |
---|
2086 | k++; |
---|
2087 | } |
---|
2088 | // k-1 = number of edges in longest path starting from 1 |
---|
2089 | return (k-1); |
---|
2090 | } else { |
---|
2091 | // GNC contains loops/cycles => there is always an n-chain |
---|
2092 | return (-1); // infinity |
---|
2093 | } |
---|
2094 | } |
---|
2095 | example |
---|
2096 | { |
---|
2097 | "EXAMPLE:"; echo = 2; |
---|
2098 | ring r = 0,(x,y),dp; |
---|
2099 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2100 | setring R; // sets basering to Letterplace ring |
---|
2101 | ideal G = x(1)*x(2), y(1)*y(2),x(1)*y(2)*x(3); // ideal G contains a |
---|
2102 | //Groebner basis |
---|
2103 | lpGlDimBound(G); // invokes procedure with Groebner basis G |
---|
2104 | } |
---|
2105 | |
---|
2106 | static proc imHasLoops(intmat A) { |
---|
2107 | int n = ncols(A); |
---|
2108 | for (int i = 1; i < n; i++) { |
---|
2109 | if (A[i,i] == 1) { |
---|
2110 | return (1); |
---|
2111 | } |
---|
2112 | } |
---|
2113 | return (0); |
---|
2114 | } |
---|
2115 | |
---|
2116 | static proc lpGraphOfNChains(ideal G) // G must be reduced |
---|
2117 | { |
---|
2118 | list LG = lpId2ivLi(lead(G)); |
---|
2119 | int n = attrib(basering, "lV"); |
---|
2120 | int degbound = attrib(basering, "uptodeg"); |
---|
2121 | |
---|
2122 | list V; |
---|
2123 | for (int i = 0; i <= n; i++) { |
---|
2124 | V[i+1] = i; // add 1 and all variables |
---|
2125 | } |
---|
2126 | for (int i = 1; i <= size(LG); i++) { |
---|
2127 | intvec u = LG[i]; |
---|
2128 | for (int j = 2; j <= size(u); j++) { |
---|
2129 | intvec v = u[j..size(u)]; |
---|
2130 | if (!contains(V, v)) { |
---|
2131 | V = insert(V, v, size(V)); // add subword j..size |
---|
2132 | } |
---|
2133 | } |
---|
2134 | } |
---|
2135 | int nV = size(V); |
---|
2136 | intmat GNC[nV][nV]; // graph of n-chains |
---|
2137 | |
---|
2138 | // for vertex 1 |
---|
2139 | for (int i = 2; i <= n + 1; i++) { |
---|
2140 | GNC[1,i] = 1; // 1 has an edge to all variables |
---|
2141 | } |
---|
2142 | |
---|
2143 | // for the other vertices |
---|
2144 | for (int i = 2; i <= nV; i++) { |
---|
2145 | for (int j = 2; j <= nV; j++) { |
---|
2146 | intvec uv = V[i],V[j]; |
---|
2147 | |
---|
2148 | if (contains(LG, uv)) { |
---|
2149 | GNC[i,j] = 1; |
---|
2150 | } else { |
---|
2151 | // Li p. 177 |
---|
2152 | // search for a right divisor 'w' of uv in G |
---|
2153 | // then check if G doesn't divide the subword uv-1 |
---|
2154 | |
---|
2155 | // look for a right divisor in LG |
---|
2156 | for (int k = 1; k <= size(LG); k++) { |
---|
2157 | if (isSF(LG[k], uv)) { |
---|
2158 | // w = LG[k] |
---|
2159 | if(!ivdivides(LG, uv[1..(size(uv)-1)])) { |
---|
2160 | // G doesn't divide uv-1 |
---|
2161 | GNC[i,j] = 1; |
---|
2162 | break; |
---|
2163 | } |
---|
2164 | } |
---|
2165 | } |
---|
2166 | } |
---|
2167 | } |
---|
2168 | } |
---|
2169 | |
---|
2170 | return(GNC); |
---|
2171 | } |
---|
2172 | |
---|
2173 | static proc contains(list L, def item) |
---|
2174 | { |
---|
2175 | for (int i = 1; i <= size(L); i++) { |
---|
2176 | if (L[i] == item) { |
---|
2177 | return (1); |
---|
2178 | } |
---|
2179 | } |
---|
2180 | return (0); |
---|
2181 | } |
---|
2182 | |
---|
2183 | |
---|
2184 | proc ivDHilbert(list L, int n, list #) |
---|
2185 | "USAGE: ivDHilbert(L,n[,degbound]); L a list of intmats, n an integer, |
---|
2186 | @* degbound an optional integer |
---|
2187 | RETURN: list |
---|
2188 | PURPOSE:Computing the K-dimension and the Hilbert series |
---|
2189 | ASSUME: - basering is a Letterplace ring |
---|
2190 | @* - all rows of each intmat correspond to a Letterplace monomial |
---|
2191 | @* - if you specify a different degree bound degbound, |
---|
2192 | @* degbound <= attrib(basering,uptodeg) holds |
---|
2193 | NOTE: - If L is the list returned, then L[1] is an integer corresponding to the |
---|
2194 | @* dimension, L[2] is an intvec which contains the coefficients of the |
---|
2195 | @* Hilbert series |
---|
2196 | @* - If degbound is set, there will be a degree bound added. By default there |
---|
2197 | @* is no degree bound |
---|
2198 | @* - n is the number of variables |
---|
2199 | @* - If I = L[2] is the intvec returned, then I[k] is the (k-1)-th coefficient of |
---|
2200 | @* the Hilbert series. |
---|
2201 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
2202 | EXAMPLE: example ivDHilbert; shows examples |
---|
2203 | " |
---|
2204 | {int degbound = 0; |
---|
2205 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] > 0){degbound = #[1];}}} |
---|
2206 | checkAssumptions(degbound,L); |
---|
2207 | intvec H; int i,dimen; |
---|
2208 | H = ivHilbert(L,n,degbound); |
---|
2209 | for (i = 1; i <= size(H); i++){dimen = dimen + H[i];} |
---|
2210 | L = dimen,H; |
---|
2211 | return(L); |
---|
2212 | } |
---|
2213 | example |
---|
2214 | { |
---|
2215 | "EXAMPLE:"; echo = 2; |
---|
2216 | ring r = 0,(x,y),dp; |
---|
2217 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2218 | R; |
---|
2219 | setring R; // sets basering to Letterplace ring |
---|
2220 | //some intmats, which contain monomials in intvec representation as rows |
---|
2221 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
2222 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
2223 | print(I1); |
---|
2224 | print(I2); |
---|
2225 | print(J1); |
---|
2226 | print(J2); |
---|
2227 | list G = I1,I2; // ideal, which is already a Groebner basis |
---|
2228 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
2229 | //the procedure without a degree bound |
---|
2230 | ivDHilbert(G,2); |
---|
2231 | // the procedure with degree bound 5 |
---|
2232 | ivDHilbert(I,2,5); |
---|
2233 | } |
---|
2234 | |
---|
2235 | proc ivDHilbertSickle(list L, int n, list #) |
---|
2236 | "USAGE: ivDHilbertSickle(L,n[,degbound]); L a list of intmats, n an integer, |
---|
2237 | @* degbound an optional integer |
---|
2238 | RETURN: list |
---|
2239 | PURPOSE:Computing K-dimension, Hilbert series and mistletoes |
---|
2240 | ASSUME: - basering is a Letterplace ring. |
---|
2241 | @* - All rows of each intmat correspond to a Letterplace monomial. |
---|
2242 | @* - If you specify a different degree bound degbound, |
---|
2243 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
2244 | NOTE: - If L is the list returned, then L[1] is an integer, L[2] is an intvec |
---|
2245 | @* which contains the coefficients of the Hilbert series and L[3] |
---|
2246 | @* is a list, containing the mistletoes as intvecs. |
---|
2247 | @* - If degbound is set, a degree bound will be added. By default there |
---|
2248 | @* is no degree bound. |
---|
2249 | @* - n is the number of variables. |
---|
2250 | @* - If I = L[2] is the intvec returned, then I[k] is the (k-1)-th |
---|
2251 | @* coefficient of the Hilbert series. |
---|
2252 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
2253 | EXAMPLE: example ivDHilbertSickle; shows examples |
---|
2254 | " |
---|
2255 | {int degbound = 0; |
---|
2256 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] > 0){degbound = #[1];}}} |
---|
2257 | checkAssumptions(degbound,L); |
---|
2258 | int i,dimen; list R; |
---|
2259 | R = ivSickleHil(L,n,degbound); |
---|
2260 | for (i = 1; i <= size(R[1]); i++){dimen = dimen + R[1][i];} |
---|
2261 | R[3] = R[2]; R[2] = R[1]; R[1] = dimen; |
---|
2262 | return(R); |
---|
2263 | } |
---|
2264 | example |
---|
2265 | { |
---|
2266 | "EXAMPLE:"; echo = 2; |
---|
2267 | ring r = 0,(x,y),dp; |
---|
2268 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2269 | R; |
---|
2270 | setring R; // sets basering to Letterplace ring |
---|
2271 | //some intmats, which contain monomials in intvec representation as rows |
---|
2272 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
2273 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
2274 | print(I1); |
---|
2275 | print(I2); |
---|
2276 | print(J1); |
---|
2277 | print(J2); |
---|
2278 | list G = I1,I2;// ideal, which is already a Groebner basis |
---|
2279 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
2280 | ivDHilbertSickle(G,2); // invokes the procedure without a degree bound |
---|
2281 | ivDHilbertSickle(I,2,3); // invokes the procedure with degree bound 3 |
---|
2282 | } |
---|
2283 | |
---|
2284 | proc ivDimCheck(list L, int n) |
---|
2285 | "USAGE: ivDimCheck(L,n); L a list of intmats, n an integer |
---|
2286 | RETURN: int, 0 if the dimension is finite, or 1 otherwise |
---|
2287 | PURPOSE:Decides, whether the K-dimension is finite or not |
---|
2288 | ASSUME: - basering is a Letterplace ring. |
---|
2289 | @* - All rows of each intmat correspond to a Letterplace monomial. |
---|
2290 | NOTE: - n is the number of variables. |
---|
2291 | EXAMPLE: example ivDimCheck; shows examples |
---|
2292 | " |
---|
2293 | {checkAssumptions(0,L); |
---|
2294 | int i,r; |
---|
2295 | intvec P,H; |
---|
2296 | for (i = 1; i <= size(L); i++) |
---|
2297 | {P[i] = ncols(L[i]); |
---|
2298 | if (P[i] == 1) {if (isInMat(H,L[i]) > 0) {ERROR("Quotient algebra is trivial");}} |
---|
2299 | } |
---|
2300 | if (size(L) == 0) {ERROR("GB is empty, quotient algebra corresponds to free algebra");} |
---|
2301 | kill H; |
---|
2302 | intmat S; int sd,ld; intvec V; |
---|
2303 | sd = P[1]; ld = P[1]; |
---|
2304 | for (i = 2; i <= size(P); i++) |
---|
2305 | {if (P[i] < sd) {sd = P[i];} |
---|
2306 | if (P[i] > ld) {ld = P[i];} |
---|
2307 | } |
---|
2308 | sd = (sd - 1); ld = ld - 1; |
---|
2309 | if (ld == 0) { return(allVars(L,P,n));} |
---|
2310 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
2311 | else {S = createStartMat(sd,n);} |
---|
2312 | module M; |
---|
2313 | for (i = 1; i <= nrows(S); i++) |
---|
2314 | {V = S[i,1..ncols(S)]; |
---|
2315 | if (findCycle(V,L,P,n,ld,M)) {r = 1; break;} |
---|
2316 | } |
---|
2317 | return(r); |
---|
2318 | } |
---|
2319 | example |
---|
2320 | { |
---|
2321 | "EXAMPLE:"; echo = 2; |
---|
2322 | ring r = 0,(x,y),dp; |
---|
2323 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2324 | R; |
---|
2325 | setring R; // sets basering to Letterplace ring |
---|
2326 | //some intmats, which contain monomials in intvec representation as rows |
---|
2327 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
2328 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
2329 | print(I1); |
---|
2330 | print(I2); |
---|
2331 | print(J1); |
---|
2332 | print(J2); |
---|
2333 | list G = I1,I2;// ideal, which is already a Groebner basis |
---|
2334 | list I = J1,J2; // ideal, which is already a Groebner basis and which |
---|
2335 | ivDimCheck(G,2); // invokes the procedure, factor is of finite K-dimension |
---|
2336 | ivDimCheck(I,2); // invokes the procedure, factor is not of finite K-dimension |
---|
2337 | } |
---|
2338 | |
---|
2339 | proc ivHilbert(list L, int n, list #) |
---|
2340 | "USAGE: ivHilbert(L,n[,degbound]); L a list of intmats, n an integer, |
---|
2341 | @* degbound an optional integer |
---|
2342 | RETURN: intvec, containing the coefficients of the Hilbert series |
---|
2343 | PURPOSE:Computing the Hilbert series |
---|
2344 | ASSUME: - basering is a Letterplace ring. |
---|
2345 | @* - all rows of each intmat correspond to a Letterplace monomial |
---|
2346 | @* - if you specify a different degree bound degbound, |
---|
2347 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
2348 | NOTE: - If degbound is set, a degree bound will be added. By default there |
---|
2349 | @* is no degree bound. |
---|
2350 | @* - n is the number of variables. |
---|
2351 | @* - If I is returned, then I[k] is the (k-1)-th coefficient of the Hilbert |
---|
2352 | @* series. |
---|
2353 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
2354 | EXAMPLE: example ivHilbert; shows examples |
---|
2355 | " |
---|
2356 | {int degbound = 0; |
---|
2357 | if (size(#) > 0) {if (typeof(#[1])=="int"){if (#[1] > 0) {degbound = #[1];}}} |
---|
2358 | intvec P,H; int i; |
---|
2359 | for (i = 1; i <= size(L); i++) |
---|
2360 | {P[i] = ncols(L[i]); |
---|
2361 | if (P[i] == 1) {if ( isInMat(H,L[i]) > 0) {ERROR("Quotient algebra is trivial");}} |
---|
2362 | } |
---|
2363 | if (size(L) == 0) {ERROR("GB is empty, quotient algebra corresponds to free algebra");} |
---|
2364 | H[1] = 1; |
---|
2365 | checkAssumptions(degbound,L); |
---|
2366 | if (degbound == 0) |
---|
2367 | {int sd; |
---|
2368 | intmat S; |
---|
2369 | sd = P[1]; |
---|
2370 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
2371 | sd = (sd - 1); |
---|
2372 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
2373 | else {S = createStartMat(sd,n);} |
---|
2374 | if (intvec(S) == 0) {return(H);} |
---|
2375 | for (i = 1; i <= sd; i++) {H = H,(n^i);} |
---|
2376 | for (i = 1; i <= nrows(S); i++) |
---|
2377 | {intvec St = S[i,1..ncols(S)]; |
---|
2378 | H = findHCoeff(St,n,L,P,H); |
---|
2379 | kill St; |
---|
2380 | } |
---|
2381 | return(H); |
---|
2382 | } |
---|
2383 | else |
---|
2384 | {for (i = 1; i <= size(P); i++) |
---|
2385 | {if (P[i] > degbound) {ERROR("degreebound is too small, GB contains elements of higher degree");}} |
---|
2386 | int sd; |
---|
2387 | intmat S; |
---|
2388 | sd = P[1]; |
---|
2389 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
2390 | sd = (sd - 1); |
---|
2391 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
2392 | else {S = createStartMat(sd,n);} |
---|
2393 | if (intvec(S) == 0) {return(H);} |
---|
2394 | for (i = 1; i <= sd; i++) {H = H,(n^i);} |
---|
2395 | for (i = 1; i <= nrows(S); i++) |
---|
2396 | {intvec St = S[i,1..ncols(S)]; |
---|
2397 | H = findHCoeff(St,n,L,P,H,degbound); |
---|
2398 | kill St; |
---|
2399 | } |
---|
2400 | return(H); |
---|
2401 | } |
---|
2402 | } |
---|
2403 | example |
---|
2404 | { |
---|
2405 | "EXAMPLE:"; echo = 2; |
---|
2406 | ring r = 0,(x,y),dp; |
---|
2407 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2408 | R; |
---|
2409 | setring R; // sets basering to Letterplace ring |
---|
2410 | //some intmats, which contain monomials in intvec representation as rows |
---|
2411 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
2412 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
2413 | print(I1); |
---|
2414 | print(I2); |
---|
2415 | print(J1); |
---|
2416 | print(J2); |
---|
2417 | list G = I1,I2; // ideal, which is already a Groebner basis |
---|
2418 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
2419 | ivHilbert(G,2); // invokes the procedure without any degree bound |
---|
2420 | ivHilbert(I,2,5); // invokes the procedure with degree bound 5 |
---|
2421 | } |
---|
2422 | |
---|
2423 | |
---|
2424 | proc ivKDim(list L, int n, list #) |
---|
2425 | "USAGE: ivKDim(L,n[,degbound]); L a list of intmats, |
---|
2426 | @* n an integer, degbound an optional integer |
---|
2427 | RETURN: int, the K-dimension of A/<L> |
---|
2428 | PURPOSE:Computing the K-dimension of A/<L> |
---|
2429 | ASSUME: - basering is a Letterplace ring. |
---|
2430 | @* - all rows of each intmat correspond to a Letterplace monomial |
---|
2431 | @* - if you specify a different degree bound degbound, |
---|
2432 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
2433 | NOTE: - If degbound is set, a degree bound will be added. By default there |
---|
2434 | @* is no degree bound. |
---|
2435 | @* - n is the number of variables. |
---|
2436 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
2437 | EXAMPLE: example ivKDim; shows examples |
---|
2438 | " |
---|
2439 | {int degbound = 0; |
---|
2440 | if (size(#) > 0) {if (typeof(#[1])=="int"){if (#[1] > 0) {degbound = #[1];}}} |
---|
2441 | intvec P,H; int i; |
---|
2442 | for (i = 1; i <= size(L); i++) |
---|
2443 | {P[i] = ncols(L[i]); |
---|
2444 | if (P[i] == 1) {if ( isInMat(H,L[i]) > 0) {ERROR("Quotient algebra is trivial");}} |
---|
2445 | } |
---|
2446 | if (size(L) == 0) {ERROR("GB is empty, quotient algebra corresponds to free algebra");} |
---|
2447 | kill H; |
---|
2448 | checkAssumptions(degbound,L); |
---|
2449 | if (degbound == 0) |
---|
2450 | {int sd; int dimen = 1; |
---|
2451 | intmat S; |
---|
2452 | sd = P[1]; |
---|
2453 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
2454 | sd = (sd - 1); |
---|
2455 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
2456 | else {S = createStartMat(sd,n);} |
---|
2457 | if (intvec(S) == 0) {return(dimen);} |
---|
2458 | for (i = 1; i <= sd; i++) {dimen = dimen +(n^i);} |
---|
2459 | for (i = 1; i <= nrows(S); i++) |
---|
2460 | {intvec St = S[i,1..ncols(S)]; |
---|
2461 | dimen = dimen + findDimen(St,n,L,P); |
---|
2462 | kill St; |
---|
2463 | } |
---|
2464 | return(dimen); |
---|
2465 | } |
---|
2466 | else |
---|
2467 | {for (i = 1; i <= size(P); i++) |
---|
2468 | {if (P[i] > degbound) {ERROR("degreebound is too small, GB contains elements of higher degree");}} |
---|
2469 | int sd; int dimen = 1; |
---|
2470 | intmat S; |
---|
2471 | sd = P[1]; |
---|
2472 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
2473 | sd = (sd - 1); |
---|
2474 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
2475 | else {S = createStartMat(sd,n);} |
---|
2476 | if (intvec(S) == 0) {return(dimen);} |
---|
2477 | for (i = 1; i <= sd; i++) {dimen = dimen +(n^i);} |
---|
2478 | for (i = 1; i <= nrows(S); i++) |
---|
2479 | {intvec St = S[i,1..ncols(S)]; |
---|
2480 | dimen = dimen + findDimen(St,n,L,P, degbound); |
---|
2481 | kill St; |
---|
2482 | } |
---|
2483 | return(dimen); |
---|
2484 | } |
---|
2485 | } |
---|
2486 | example |
---|
2487 | { |
---|
2488 | "EXAMPLE:"; echo = 2; |
---|
2489 | ring r = 0,(x,y),dp; |
---|
2490 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2491 | R; |
---|
2492 | setring R; // sets basering to Letterplace ring |
---|
2493 | //some intmats, which contain monomials in intvec representation as rows |
---|
2494 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
2495 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
2496 | print(I1); |
---|
2497 | print(I2); |
---|
2498 | print(J1); |
---|
2499 | print(J2); |
---|
2500 | list G = I1,I2; // ideal, which is already a Groebner basis |
---|
2501 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
2502 | ivKDim(G,2); // invokes the procedure without any degree bound |
---|
2503 | ivKDim(I,2,5); // invokes the procedure with degree bound 5 |
---|
2504 | } |
---|
2505 | |
---|
2506 | proc ivMis2Base(list M) |
---|
2507 | "USAGE: ivMis2Base(M); M a list of intvecs |
---|
2508 | RETURN: ideal, a K-base of the given algebra |
---|
2509 | PURPOSE:Computing the K-base out of given mistletoes |
---|
2510 | ASSUME: - The mistletoes have to be ordered lexicographically -> OrdMisLex. |
---|
2511 | @* Otherwise there might some elements missing. |
---|
2512 | @* - basering is a Letterplace ring. |
---|
2513 | @* - mistletoes are stored as intvecs, as described in the overview |
---|
2514 | EXAMPLE: example ivMis2Base; shows examples |
---|
2515 | " |
---|
2516 | { |
---|
2517 | //checkAssumptions(0,M); |
---|
2518 | intvec L,A; |
---|
2519 | if (size(M) == 0){ERROR("There are no mistletoes, so it appears your dimension is infinite!");} |
---|
2520 | if (isInList(L,M) > 0) {print("1 is a mistletoe, therefore 1 is the only basis element"); return(list(intvec(0)));} |
---|
2521 | int i,j,d,s; |
---|
2522 | list Rt; |
---|
2523 | Rt[1] = intvec(0); |
---|
2524 | L = M[1]; |
---|
2525 | for (i = size(L); 1 <= i; i--) {Rt = insert(Rt,intvec(L[1..i]));} |
---|
2526 | for (i = 2; i <= size(M); i++) |
---|
2527 | {A = M[i]; L = M[i-1]; |
---|
2528 | s = size(A); |
---|
2529 | if (s > size(L)) |
---|
2530 | {d = size(L); |
---|
2531 | for (j = s; j > d; j--) {Rt = insert(Rt,intvec(A[1..j]));} |
---|
2532 | A = A[1..d]; |
---|
2533 | } |
---|
2534 | if (size(L) > s){L = L[1..s];} |
---|
2535 | while (A <> L) |
---|
2536 | {Rt = insert(Rt, intvec(A)); |
---|
2537 | if (size(A) > 1) |
---|
2538 | {A = A[1..(size(A)-1)]; |
---|
2539 | L = L[1..(size(L)-1)]; |
---|
2540 | } |
---|
2541 | else {break;} |
---|
2542 | } |
---|
2543 | } |
---|
2544 | return(Rt); |
---|
2545 | } |
---|
2546 | example |
---|
2547 | { |
---|
2548 | "EXAMPLE:"; echo = 2; |
---|
2549 | ring r = 0,(x,y),dp; |
---|
2550 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2551 | R; |
---|
2552 | setring R; // sets basering to Letterplace ring |
---|
2553 | intvec i1 = 1,2; intvec i2 = 2,1,2; |
---|
2554 | // the mistletoes are xy and yxy, which are already ordered lexicographically |
---|
2555 | list L = i1,i2; |
---|
2556 | ivMis2Base(L); // returns the basis of the factor algebra |
---|
2557 | } |
---|
2558 | |
---|
2559 | |
---|
2560 | proc ivMis2Dim(list M) |
---|
2561 | "USAGE: ivMis2Dim(M); M a list of intvecs |
---|
2562 | RETURN: int, the K-dimension of the given algebra |
---|
2563 | PURPOSE:Computing the K-dimension out of given mistletoes |
---|
2564 | ASSUME: - The mistletoes have to be ordered lexicographically -> OrdMisLex. |
---|
2565 | @* Otherwise the returned value may differ from the K-dimension. |
---|
2566 | @* - basering is a Letterplace ring. |
---|
2567 | EXAMPLE: example ivMis2Dim; shows examples |
---|
2568 | " |
---|
2569 | {checkAssumptions(0,M); |
---|
2570 | intvec L; |
---|
2571 | if (size(M) == 0){ERROR("There are no mistletoes, so it appears your dimension is infinite!");} |
---|
2572 | if (isInList(L,M) > 0) {print("1 is a mistletoe, therefore dim = 1"); return(1);} |
---|
2573 | int i,j,d,s; |
---|
2574 | j = 1; |
---|
2575 | d = 1 + size(M[1]); |
---|
2576 | for (i = 1; i < size(M); i++) |
---|
2577 | {s = size(M[i]); if (s > size(M[i+1])){s = size(M[i+1]);} |
---|
2578 | while ((M[i][j] == M[i+1][j]) && (j <= s)){j = j + 1;} |
---|
2579 | d = d + size(M[i+1])- j + 1; |
---|
2580 | } |
---|
2581 | return(d); |
---|
2582 | } |
---|
2583 | example |
---|
2584 | { |
---|
2585 | "EXAMPLE:"; echo = 2; |
---|
2586 | ring r = 0,(x,y),dp; |
---|
2587 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2588 | R; |
---|
2589 | setring R; // sets basering to Letterplace ring |
---|
2590 | intvec i1 = 1,2; intvec i2 = 2,1,2; |
---|
2591 | // the mistletoes are xy and yxy, which are already ordered lexicographically |
---|
2592 | list L = i1,i2; |
---|
2593 | ivMis2Dim(L); // returns the dimension of the factor algebra |
---|
2594 | } |
---|
2595 | |
---|
2596 | proc ivOrdMisLex(list M) |
---|
2597 | "USAGE: ivOrdMisLex(M); M a list of intvecs |
---|
2598 | RETURN: list, containing the ordered intvecs of M |
---|
2599 | PURPOSE:Orders a given set of mistletoes lexicographically |
---|
2600 | ASSUME: - basering is a Letterplace ring. |
---|
2601 | - intvecs correspond to monomials |
---|
2602 | NOTE: - This is preprocessing, it's not needed if the mistletoes are returned |
---|
2603 | @* from the sickle algorithm. |
---|
2604 | @* - Each entry of the list returned is an intvec. |
---|
2605 | EXAMPLE: example ivOrdMisLex; shows examples |
---|
2606 | " |
---|
2607 | {checkAssumptions(0,M); |
---|
2608 | return(sort(M)[1]); |
---|
2609 | } |
---|
2610 | example |
---|
2611 | { |
---|
2612 | "EXAMPLE:"; echo = 2; |
---|
2613 | ring r = 0,(x,y),dp; |
---|
2614 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2615 | setring R; // sets basering to Letterplace ring |
---|
2616 | intvec i1 = 1,2,1; intvec i2 = 2,2,1; intvec i3 = 1,1; intvec i4 = 2,1,1,1; |
---|
2617 | // the corresponding monomials are xyx,y^2x,x^2,yx^3 |
---|
2618 | list M = i1,i2,i3,i4; |
---|
2619 | M; |
---|
2620 | ivOrdMisLex(M);// orders the list of monomials |
---|
2621 | } |
---|
2622 | |
---|
2623 | proc ivSickle(list L, int n, list #) |
---|
2624 | "USAGE: ivSickle(L,n,[degbound]); L a list of intmats, n an int, degbound an |
---|
2625 | @* optional integer |
---|
2626 | RETURN: list, containing intvecs, the mistletoes of A/<L> |
---|
2627 | PURPOSE:Computing the mistletoes for a given Groebner basis L |
---|
2628 | ASSUME: - basering is a Letterplace ring. |
---|
2629 | @* - all rows of each intmat correspond to a Letterplace monomial |
---|
2630 | @* - if you specify a different degree bound degbound, |
---|
2631 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
2632 | NOTE: - If degbound is set, a degree bound will be added. By default there |
---|
2633 | @* is no degree bound. |
---|
2634 | @* - n is the number of variables. |
---|
2635 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
2636 | EXAMPLE: example ivSickle; shows examples |
---|
2637 | " |
---|
2638 | {list M; |
---|
2639 | int degbound = 0; |
---|
2640 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] > 0){degbound = #[1];}}} |
---|
2641 | int i; |
---|
2642 | intvec P,H; |
---|
2643 | for (i = 1; i <= size(L); i++) |
---|
2644 | {P[i] = ncols(L[i]); |
---|
2645 | if (P[i] == 1) {if (isInMat(H,L[i]) > 0) {ERROR("Quotient algebra is trivial");}} |
---|
2646 | } |
---|
2647 | if (size(L) == 0) {ERROR("GB is empty, quotient algebra corresponds to free algebra");} |
---|
2648 | kill H; |
---|
2649 | checkAssumptions(degbound,L); |
---|
2650 | if (degbound == 0) |
---|
2651 | {intmat S; int sd; |
---|
2652 | sd = P[1]; |
---|
2653 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
2654 | sd = (sd - 1); |
---|
2655 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
2656 | else {S = createStartMat(sd,n);} |
---|
2657 | if (intvec(S) == 0) {return(list (intvec(0)));} |
---|
2658 | for (i = 1; i <= nrows(S); i++) |
---|
2659 | {intvec St = S[i,1..ncols(S)]; |
---|
2660 | M = M + findmistletoes(St,n,L,P); |
---|
2661 | kill St; |
---|
2662 | } |
---|
2663 | return(M); |
---|
2664 | } |
---|
2665 | else |
---|
2666 | {for (i = 1; i <= size(P); i++) |
---|
2667 | {if (P[i] > degbound) {ERROR("degreebound is too small, GB contains elements of higher degree");}} |
---|
2668 | intmat S; int sd; |
---|
2669 | sd = P[1]; |
---|
2670 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
2671 | sd = (sd - 1); |
---|
2672 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
2673 | else {S = createStartMat(sd,n);} |
---|
2674 | if (intvec(S) == 0) {return(list (intvec(0)));} |
---|
2675 | for (i = 1; i <= nrows(S); i++) |
---|
2676 | {intvec St = S[i,1..ncols(S)]; |
---|
2677 | M = M + findmistletoes(St,n,L,P,degbound); |
---|
2678 | kill St; |
---|
2679 | } |
---|
2680 | return(M); |
---|
2681 | } |
---|
2682 | } |
---|
2683 | example |
---|
2684 | { |
---|
2685 | "EXAMPLE:"; echo = 2; |
---|
2686 | ring r = 0,(x,y),dp; |
---|
2687 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2688 | setring R; // sets basering to Letterplace ring |
---|
2689 | //some intmats, which contain monomials in intvec representation as rows |
---|
2690 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
2691 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
2692 | print(I1); |
---|
2693 | print(I2); |
---|
2694 | print(J1); |
---|
2695 | print(J2); |
---|
2696 | list G = I1,I2; // ideal, which is already a Groebner basis |
---|
2697 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
2698 | ivSickle(G,2); // invokes the procedure without any degree bound |
---|
2699 | ivSickle(I,2,5); // invokes the procedure with degree bound 5 |
---|
2700 | } |
---|
2701 | |
---|
2702 | proc ivSickleDim(list L, int n, list #) |
---|
2703 | "USAGE: ivSickleDim(L,n[,degbound]); L a list of intmats, n an integer, degbound |
---|
2704 | @* an optional integer |
---|
2705 | RETURN: list |
---|
2706 | PURPOSE:Computing mistletoes and the K-dimension |
---|
2707 | ASSUME: - basering is a Letterplace ring. |
---|
2708 | @* - all rows of each intmat correspond to a Letterplace monomial |
---|
2709 | @* - if you specify a different degree bound degbound, |
---|
2710 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
2711 | NOTE: - If L is the list returned, then L[1] is an integer, L[2] is a list, |
---|
2712 | @* containing the mistletoes as intvecs. |
---|
2713 | @* - If degbound is set, a degree bound will be added. By default there |
---|
2714 | @* is no degree bound. |
---|
2715 | @* - n is the number of variables. |
---|
2716 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
2717 | EXAMPLE: example ivSickleDim; shows examples |
---|
2718 | " |
---|
2719 | {list M; |
---|
2720 | int degbound = 0; |
---|
2721 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] > 0){degbound = #[1];}}} |
---|
2722 | int i,dimen; list R; |
---|
2723 | intvec P,H; |
---|
2724 | for (i = 1; i <= size(L); i++) |
---|
2725 | {P[i] = ncols(L[i]); |
---|
2726 | if (P[i] == 1) {if (isInMat(H,L[i]) > 0) {ERROR("Quotient algebra is trivial, dimension equals zero");}} |
---|
2727 | } |
---|
2728 | if (size(L) == 0) {ERROR("GB is empty, quotient algebra corresponds to free algebra");} |
---|
2729 | kill H; |
---|
2730 | checkAssumptions(degbound,L); |
---|
2731 | if (degbound == 0) |
---|
2732 | {int sd; dimen = 1; |
---|
2733 | intmat S; |
---|
2734 | sd = P[1]; |
---|
2735 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
2736 | sd = (sd - 1); |
---|
2737 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
2738 | else {S = createStartMat(sd,n);} |
---|
2739 | if (intvec(S) == 0) {return(list(dimen,list(intvec(0))));} |
---|
2740 | for (i = 1; i <= sd; i++) {dimen = dimen +(n^i);} |
---|
2741 | R[1] = dimen; |
---|
2742 | for (i = 1; i <= nrows(S); i++) |
---|
2743 | {intvec St = S[i,1..ncols(S)]; |
---|
2744 | R = findMisDim(St,n,L,P,R); |
---|
2745 | kill St; |
---|
2746 | } |
---|
2747 | return(R); |
---|
2748 | } |
---|
2749 | else |
---|
2750 | {for (i = 1; i <= size(P); i++) |
---|
2751 | {if (P[i] > degbound) {ERROR("degreebound is too small, GB contains elements of higher degree");}} |
---|
2752 | int sd; dimen = 1; |
---|
2753 | intmat S; |
---|
2754 | sd = P[1]; |
---|
2755 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
2756 | sd = (sd - 1); |
---|
2757 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
2758 | else {S = createStartMat(sd,n);} |
---|
2759 | if (intvec(S) == 0) {return(list(dimen,list(intvec(0))));} |
---|
2760 | for (i = 1; i <= sd; i++) {dimen = dimen +(n^i);} |
---|
2761 | R[1] = dimen; |
---|
2762 | for (i = 1; i <= nrows(S); i++) |
---|
2763 | {intvec St = S[i,1..ncols(S)]; |
---|
2764 | R = findMisDim(St,n,L,P,R,degbound); |
---|
2765 | kill St; |
---|
2766 | } |
---|
2767 | return(R); |
---|
2768 | } |
---|
2769 | } |
---|
2770 | example |
---|
2771 | { |
---|
2772 | "EXAMPLE:"; echo = 2; |
---|
2773 | ring r = 0,(x,y),dp; |
---|
2774 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2775 | setring R; // sets basering to Letterplace ring |
---|
2776 | //some intmats, which contain monomials in intvec representation as rows |
---|
2777 | intmat I1 [2][2] = 1,1,2,2; intmat I2 [1][3] = 1,2,1; |
---|
2778 | intmat J1 [1][2] = 1,1; intmat J2 [2][3] = 2,1,2,1,2,1; |
---|
2779 | print(I1); |
---|
2780 | print(I2); |
---|
2781 | print(J1); |
---|
2782 | print(J2); |
---|
2783 | list G = I1,I2;// ideal, which is already a Groebner basis |
---|
2784 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
2785 | ivSickleDim(G,2); // invokes the procedure without any degree bound |
---|
2786 | ivSickleDim(I,2,5); // invokes the procedure with degree bound 5 |
---|
2787 | } |
---|
2788 | |
---|
2789 | proc ivSickleHil(list L, int n, list #) |
---|
2790 | "USAGE:ivSickleHil(L,n[,degbound]); L a list of intmats, n an integer, |
---|
2791 | @* degbound an optional integer |
---|
2792 | RETURN: list |
---|
2793 | PURPOSE:Computing the mistletoes and the Hilbert series |
---|
2794 | ASSUME: - basering is a Letterplace ring. |
---|
2795 | @* - all rows of each intmat correspond to a Letterplace monomial |
---|
2796 | @* - if you specify a different degree bound degbound, |
---|
2797 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
2798 | NOTE: - If L is the list returned, then L[1] is an intvec, L[2] is a list, |
---|
2799 | @* containing the mistletoes as intvecs. |
---|
2800 | @* - If degbound is set, a degree bound will be added. By default there |
---|
2801 | @* is no degree bound. |
---|
2802 | @* - n is the number of variables. |
---|
2803 | @* - If I = L[1] is the intvec returned, then I[k] is the (k-1)-th |
---|
2804 | @* coefficient of the Hilbert series. |
---|
2805 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
2806 | EXAMPLE: example ivSickleHil; shows examples |
---|
2807 | " |
---|
2808 | {int degbound = 0; |
---|
2809 | if (size(#) > 0) {if (typeof(#[1])=="int"){if (#[1] > 0) {degbound = #[1];}}} |
---|
2810 | intvec P,H; int i; list R; |
---|
2811 | for (i = 1; i <= size(L); i++) |
---|
2812 | {P[i] = ncols(L[i]); |
---|
2813 | if (P[i] == 1) {if ( isInMat(H,L[i]) > 0) {ERROR("Quotient algebra is trivial");}} |
---|
2814 | } |
---|
2815 | if (size(L) == 0) {ERROR("GB is empty, quotient algebra corresponds to free algebra");} |
---|
2816 | H[1] = 1; |
---|
2817 | checkAssumptions(degbound,L); |
---|
2818 | if (degbound == 0) |
---|
2819 | {int sd; |
---|
2820 | intmat S; |
---|
2821 | sd = P[1]; |
---|
2822 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
2823 | sd = (sd - 1); |
---|
2824 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
2825 | else {S = createStartMat(sd,n);} |
---|
2826 | if (intvec(S) == 0) {return(list(H,list(intvec (0))));} |
---|
2827 | for (i = 1; i <= sd; i++) {H = H,(n^i);} |
---|
2828 | R[1] = H; kill H; |
---|
2829 | for (i = 1; i <= nrows(S); i++) |
---|
2830 | {intvec St = S[i,1..ncols(S)]; |
---|
2831 | R = findHCoeffMis(St,n,L,P,R); |
---|
2832 | kill St; |
---|
2833 | } |
---|
2834 | return(R); |
---|
2835 | } |
---|
2836 | else |
---|
2837 | {for (i = 1; i <= size(P); i++) |
---|
2838 | {if (P[i] > degbound) {ERROR("degreebound is too small, GB contains elements of higher degree");}} |
---|
2839 | int sd; |
---|
2840 | intmat S; |
---|
2841 | sd = P[1]; |
---|
2842 | for (i = 2; i <= size(P); i++) {if (P[i] < sd) {sd = P[i];}} |
---|
2843 | sd = (sd - 1); |
---|
2844 | if (sd == 0) { for (i = 1; i <= size(L); i++){if (ncols(L[i]) == 1){S = createStartMat1(n,L[i]); break;}}} |
---|
2845 | else {S = createStartMat(sd,n);} |
---|
2846 | if (intvec(S) == 0) {return(list(H,list(intvec(0))));} |
---|
2847 | for (i = 1; i <= sd; i++) {H = H,(n^i);} |
---|
2848 | R[1] = H; kill H; |
---|
2849 | for (i = 1; i <= nrows(S); i++) |
---|
2850 | {intvec St = S[i,1..ncols(S)]; |
---|
2851 | R = findHCoeffMis(St,n,L,P,R,degbound); |
---|
2852 | kill St; |
---|
2853 | } |
---|
2854 | return(R); |
---|
2855 | } |
---|
2856 | } |
---|
2857 | example |
---|
2858 | { |
---|
2859 | "EXAMPLE:"; echo = 2; |
---|
2860 | ring r = 0,(x,y),dp; |
---|
2861 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2862 | setring R; // sets basering to Letterplace ring |
---|
2863 | //some intmats, which contain monomials in intvec representation as rows |
---|
2864 | intmat I1[2][2] = 1,1,2,2; intmat I2[1][3] = 1,2,1; |
---|
2865 | intmat J1[1][2] = 1,1; intmat J2[2][3] = 2,1,2,1,2,1; |
---|
2866 | print(I1); |
---|
2867 | print(I2); |
---|
2868 | print(J1); |
---|
2869 | print(J2); |
---|
2870 | list G = I1,I2;// ideal, which is already a Groebner basis |
---|
2871 | list I = J1,J2; // ideal, which is already a Groebner basis |
---|
2872 | ivSickleHil(G,2); // invokes the procedure without any degree bound |
---|
2873 | ivSickleHil(I,2,5); // invokes the procedure with degree bound 5 |
---|
2874 | } |
---|
2875 | |
---|
2876 | proc lpDHilbert(ideal G, list #) |
---|
2877 | "USAGE: lpDHilbert(G[,degbound,n]); G an ideal, degbound, n optional integers |
---|
2878 | RETURN: list |
---|
2879 | PURPOSE:Computing K-dimension and Hilbert series, starting with a lp-ideal |
---|
2880 | ASSUME: - basering is a Letterplace ring. |
---|
2881 | @* - if you specify a different degree bound degbound, |
---|
2882 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
2883 | NOTE: - If L is the list returned, then L[1] is an integer corresponding to the |
---|
2884 | @* dimension, L[2] is an intvec which contains the coefficients of the |
---|
2885 | @* Hilbert series |
---|
2886 | @* - If degbound is set, there will be a degree bound added. 0 means no |
---|
2887 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
2888 | @* - n can be set to a different number of variables. |
---|
2889 | @* Default: n = attrib(basering, lV). |
---|
2890 | @* - If I = L[2] is the intvec returned, then I[k] is the (k-1)-th |
---|
2891 | @* coefficient of the Hilbert series. |
---|
2892 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
2893 | EXAMPLE: example lpDHilbert; shows examples |
---|
2894 | " |
---|
2895 | {int degbound = attrib(basering,"uptodeg");int n = attrib(basering, "lV"); |
---|
2896 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
2897 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
2898 | list L; |
---|
2899 | L = lp2ivId(normalize(lead(G))); |
---|
2900 | return(ivDHilbert(L,n,degbound)); |
---|
2901 | } |
---|
2902 | example |
---|
2903 | { |
---|
2904 | "EXAMPLE:"; echo = 2; |
---|
2905 | ring r = 0,(x,y),dp; |
---|
2906 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2907 | setring R; // sets basering to Letterplace ring |
---|
2908 | ideal G = x(1)*x(2), y(1)*y(2),x(1)*y(2)*x(3); // ideal G contains a |
---|
2909 | //Groebner basis |
---|
2910 | lpDHilbert(G,5,2); // invokes procedure with degree bound 5 and 2 variables |
---|
2911 | // note that the optional parameters are not necessary, due to the finiteness |
---|
2912 | // of the K-dimension of the factor algebra |
---|
2913 | lpDHilbert(G); // procedure with ring parameters |
---|
2914 | lpDHilbert(G,0); // procedure without degreebound |
---|
2915 | } |
---|
2916 | |
---|
2917 | proc lpDHilbertSickle(ideal G, list #) |
---|
2918 | "USAGE: lpDHilbertSickle(G[,degbound,n]); G an ideal, degbound, n optional |
---|
2919 | @* integers |
---|
2920 | RETURN: list |
---|
2921 | PURPOSE:Computing K-dimension, Hilbert series and mistletoes at once |
---|
2922 | ASSUME: - basering is a Letterplace ring. |
---|
2923 | @* - if you specify a different degree bound degbound, |
---|
2924 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
2925 | NOTE: - If L is the list returned, then L[1] is an integer, the K-dimension, |
---|
2926 | @* L[2] is an intvec, the Hilbert series and L[3] is an ideal, |
---|
2927 | @* the mistletoes |
---|
2928 | @* - If degbound is set, there will be a degree bound added. 0 means no |
---|
2929 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
2930 | @* - n can be set to a different number of variables. |
---|
2931 | @* Default: n = attrib(basering, lV). |
---|
2932 | @* - If I = L[1] is the intvec returned, then I[k] is the (k-1)-th |
---|
2933 | @* coefficient of the Hilbert series. |
---|
2934 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
2935 | EXAMPLE: example lpDHilbertSickle; shows examples |
---|
2936 | " |
---|
2937 | {int degbound = attrib(basering,"uptodeg");int n = attrib(basering, "lV"); |
---|
2938 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
2939 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
2940 | list L; |
---|
2941 | L = lp2ivId(normalize(lead(G))); |
---|
2942 | L = ivDHilbertSickle(L,n,degbound); |
---|
2943 | L[3] = ivL2lpI(L[3]); |
---|
2944 | return(L); |
---|
2945 | } |
---|
2946 | example |
---|
2947 | { |
---|
2948 | "EXAMPLE:"; echo = 2; |
---|
2949 | ring r = 0,(x,y),dp; |
---|
2950 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2951 | setring R; // sets basering to Letterplace ring |
---|
2952 | ideal G = x(1)*x(2), y(1)*y(2),x(1)*y(2)*x(3); // ideal G contains a |
---|
2953 | //Groebner basis |
---|
2954 | lpDHilbertSickle(G,5,2); //invokes procedure with degree bound 5 and 2 variables |
---|
2955 | // note that the optional parameters are not necessary, due to the finiteness |
---|
2956 | // of the K-dimension of the factor algebra |
---|
2957 | lpDHilbertSickle(G); // procedure with ring parameters |
---|
2958 | lpDHilbertSickle(G,0); // procedure without degreebound |
---|
2959 | } |
---|
2960 | |
---|
2961 | proc lpHilbert(ideal G, list #) |
---|
2962 | "USAGE: lpHilbert(G[,degbound,n]); G an ideal, degbound, n optional integers |
---|
2963 | RETURN: intvec, containing the coefficients of the Hilbert series |
---|
2964 | PURPOSE:Computing the Hilbert series |
---|
2965 | ASSUME: - basering is a Letterplace ring. |
---|
2966 | @* - if you specify a different degree bound degbound, |
---|
2967 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
2968 | NOTE: - If degbound is set, there will be a degree bound added. 0 means no |
---|
2969 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
2970 | @* - n is the number of variables, which can be set to a different number. |
---|
2971 | @* Default: attrib(basering, lV). |
---|
2972 | @* - If I is returned, then I[k] is the (k-1)-th coefficient of the Hilbert |
---|
2973 | @* series. |
---|
2974 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
2975 | EXAMPLE: example lpHilbert; shows examples |
---|
2976 | " |
---|
2977 | {int degbound = attrib(basering,"uptodeg");int n = attrib(basering, "lV"); |
---|
2978 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
2979 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
2980 | list L; |
---|
2981 | L = lp2ivId(normalize(lead(G))); |
---|
2982 | return(ivHilbert(L,n,degbound)); |
---|
2983 | } |
---|
2984 | example |
---|
2985 | { |
---|
2986 | "EXAMPLE:"; echo = 2; |
---|
2987 | ring r = 0,(x,y),dp; |
---|
2988 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
2989 | setring R; // sets basering to Letterplace ring |
---|
2990 | ideal G = x(1)*x(2), y(1)*y(2),x(1)*y(2)*x(3); // ideal G contains a |
---|
2991 | //Groebner basis |
---|
2992 | lpHilbert(G,5,2); // invokes procedure with degree bound 5 and 2 variables |
---|
2993 | // note that the optional parameters are not necessary, due to the finiteness |
---|
2994 | // of the K-dimension of the factor algebra |
---|
2995 | lpDHilbert(G); // procedure with ring parameters |
---|
2996 | lpDHilbert(G,0); // procedure without degreebound |
---|
2997 | } |
---|
2998 | |
---|
2999 | proc lpDimCheck(ideal G) |
---|
3000 | "USAGE: lpDimCheck(G); |
---|
3001 | RETURN: int, 1 if K-dimension of the factor algebra is infinite, 0 otherwise |
---|
3002 | PURPOSE:Checking a factor algebra for finiteness of the K-dimension |
---|
3003 | ASSUME: - basering is a Letterplace ring. |
---|
3004 | EXAMPLE: example lpDimCheck; shows examples |
---|
3005 | " |
---|
3006 | {int n = attrib(basering,"lV"); |
---|
3007 | list L; |
---|
3008 | ideal R; |
---|
3009 | R = normalize(lead(G)); |
---|
3010 | L = lp2ivId(R); |
---|
3011 | return(ivDimCheck(L,n)); |
---|
3012 | } |
---|
3013 | example |
---|
3014 | { |
---|
3015 | "EXAMPLE:"; echo = 2; |
---|
3016 | ring r = 0,(x,y),dp; |
---|
3017 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
3018 | setring R; // sets basering to Letterplace ring |
---|
3019 | ideal G = x(1)*x(2), y(1)*y(2),x(1)*y(2)*x(3); |
---|
3020 | // Groebner basis |
---|
3021 | ideal I = x(1)*x(2), y(1)*x(2)*y(3), x(1)*y(2)*x(3); |
---|
3022 | // Groebner basis |
---|
3023 | lpDimCheck(G); // invokes procedure, factor algebra is of finite K-dimension |
---|
3024 | lpDimCheck(I); // invokes procedure, factor algebra is of infinite Kdimension |
---|
3025 | } |
---|
3026 | |
---|
3027 | proc lpKDim(ideal G, list #) |
---|
3028 | "USAGE: lpKDim(G[,degbound, n]); G an ideal, degbound, n optional integers |
---|
3029 | RETURN: int, the K-dimension of the factor algebra |
---|
3030 | PURPOSE:Computing the K-dimension of a factor algebra, given via an ideal |
---|
3031 | ASSUME: - basering is a Letterplace ring |
---|
3032 | @* - if you specify a different degree bound degbound, |
---|
3033 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
3034 | NOTE: - If degbound is set, there will be a degree bound added. 0 means no |
---|
3035 | @* degree bound. Default: attrib(basering, uptodeg). |
---|
3036 | @* - n is the number of variables, which can be set to a different number. |
---|
3037 | @* Default: attrib(basering, lV). |
---|
3038 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
3039 | EXAMPLE: example lpKDim; shows examples |
---|
3040 | " |
---|
3041 | {int degbound = attrib(basering, "uptodeg");int n = attrib(basering, "lV"); |
---|
3042 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
3043 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
3044 | list L; |
---|
3045 | L = lp2ivId(normalize(lead(G))); |
---|
3046 | return(ivKDim(L,n,degbound)); |
---|
3047 | } |
---|
3048 | example |
---|
3049 | { |
---|
3050 | "EXAMPLE:"; echo = 2; |
---|
3051 | ring r = 0,(x,y),dp; |
---|
3052 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
3053 | setring R; // sets basering to Letterplace ring |
---|
3054 | ideal G = x(1)*x(2), y(1)*y(2),x(1)*y(2)*x(3); |
---|
3055 | // ideal G contains a Groebner basis |
---|
3056 | lpKDim(G); //procedure invoked with ring parameters |
---|
3057 | // the factor algebra is finite, so the degree bound given by the Letterplace |
---|
3058 | // ring is not necessary |
---|
3059 | lpKDim(G,0); // procedure without any degree bound |
---|
3060 | } |
---|
3061 | |
---|
3062 | proc lpMis2Base(ideal M) |
---|
3063 | "USAGE: lpMis2Base(M); M an ideal |
---|
3064 | RETURN: ideal, a K-basis of the factor algebra |
---|
3065 | PURPOSE:Computing a K-basis out of given mistletoes |
---|
3066 | ASSUME: - basering is a Letterplace ring. G is a Letterplace ideal. |
---|
3067 | @* - M contains only monomials |
---|
3068 | NOTE: - The mistletoes have to be ordered lexicographically -> OrdMisLex. |
---|
3069 | EXAMPLE: example lpMis2Base; shows examples |
---|
3070 | " |
---|
3071 | {list L; |
---|
3072 | L = lpId2ivLi(M); |
---|
3073 | return(ivL2lpI(ivMis2Base(L))); |
---|
3074 | } |
---|
3075 | example |
---|
3076 | { |
---|
3077 | "EXAMPLE:"; echo = 2; |
---|
3078 | ring r = 0,(x,y),dp; |
---|
3079 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
3080 | setring R; // sets basering to Letterplace ring |
---|
3081 | ideal L = x(1)*y(2),y(1)*x(2)*y(3); |
---|
3082 | // ideal containing the mistletoes |
---|
3083 | lpMis2Base(L); // returns the K-basis of the factor algebra |
---|
3084 | } |
---|
3085 | |
---|
3086 | proc lpMis2Dim(ideal M) |
---|
3087 | "USAGE: lpMis2Dim(M); M an ideal |
---|
3088 | RETURN: int, the K-dimension of the factor algebra |
---|
3089 | PURPOSE:Computing the K-dimension out of given mistletoes |
---|
3090 | ASSUME: - basering is a Letterplace ring. |
---|
3091 | @* - M contains only monomials |
---|
3092 | NOTE: - The mistletoes have to be ordered lexicographically -> OrdMisLex. |
---|
3093 | EXAMPLE: example lpMis2Dim; shows examples |
---|
3094 | " |
---|
3095 | {list L; |
---|
3096 | L = lpId2ivLi(M); |
---|
3097 | return(ivMis2Dim(L)); |
---|
3098 | } |
---|
3099 | example |
---|
3100 | { |
---|
3101 | "EXAMPLE:"; echo = 2; |
---|
3102 | ring r = 0,(x,y),dp; |
---|
3103 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
3104 | setring R; // sets basering to Letterplace ring |
---|
3105 | ideal L = x(1)*y(2),y(1)*x(2)*y(3); |
---|
3106 | // ideal containing the mistletoes |
---|
3107 | lpMis2Dim(L); // returns the K-dimension of the factor algebra |
---|
3108 | } |
---|
3109 | |
---|
3110 | proc lpOrdMisLex(ideal M) |
---|
3111 | "USAGE: lpOrdMisLex(M); M an ideal of mistletoes |
---|
3112 | RETURN: ideal, containing the mistletoes, ordered lexicographically |
---|
3113 | PURPOSE:A given set of mistletoes is ordered lexicographically |
---|
3114 | ASSUME: - basering is a Letterplace ring. |
---|
3115 | NOTE: This is preprocessing, it is not needed if the mistletoes are returned |
---|
3116 | @* from the sickle algorithm. |
---|
3117 | EXAMPLE: example lpOrdMisLex; shows examples |
---|
3118 | " |
---|
3119 | {return(ivL2lpI(sort(lpId2ivLi(M))[1]));} |
---|
3120 | example |
---|
3121 | { |
---|
3122 | "EXAMPLE:"; echo = 2; |
---|
3123 | ring r = 0,(x,y),dp; |
---|
3124 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
3125 | setring R; // sets basering to Letterplace ring |
---|
3126 | ideal M = x(1)*y(2)*x(3), y(1)*y(2)*x(3), x(1)*x(2), y(1)*x(2)*x(3)*x(4); |
---|
3127 | // some monomials |
---|
3128 | lpOrdMisLex(M); // orders the monomials lexicographically |
---|
3129 | } |
---|
3130 | |
---|
3131 | proc lpSickle(ideal G, list #) |
---|
3132 | "USAGE: lpSickle(G[,degbound,n]); G an ideal, degbound, n optional integers |
---|
3133 | RETURN: ideal |
---|
3134 | PURPOSE:Computing the mistletoes of K[X]/<G> |
---|
3135 | ASSUME: - basering is a Letterplace ring. |
---|
3136 | @* - if you specify a different degree bound degbound, |
---|
3137 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
3138 | NOTE: - If degbound is set, there will be a degree bound added. 0 means no |
---|
3139 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
3140 | @* - n is the number of variables, which can be set to a different number. |
---|
3141 | @* Default: attrib(basering, lV). |
---|
3142 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
3143 | EXAMPLE: example lpSickle; shows examples |
---|
3144 | " |
---|
3145 | {int degbound = attrib(basering,"uptodeg"); int n = attrib(basering, "lV"); |
---|
3146 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
3147 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
3148 | list L; ideal R; |
---|
3149 | R = normalize(lead(G)); |
---|
3150 | L = lp2ivId(R); |
---|
3151 | L = ivSickle(L,n,degbound); |
---|
3152 | R = ivL2lpI(L); |
---|
3153 | return(R); |
---|
3154 | } |
---|
3155 | example |
---|
3156 | { |
---|
3157 | "EXAMPLE:"; echo = 2; |
---|
3158 | ring r = 0,(x,y),dp; |
---|
3159 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
3160 | setring R; // sets basering to Letterplace ring |
---|
3161 | ideal G = x(1)*x(2), y(1)*y(2),x(1)*y(2)*x(3); // ideal G contains a |
---|
3162 | //Groebner basis |
---|
3163 | lpSickle(G); //invokes the procedure with ring parameters |
---|
3164 | // the factor algebra is finite, so the degree bound given by the Letterplace |
---|
3165 | // ring is not necessary |
---|
3166 | lpSickle(G,0); // procedure without any degree bound |
---|
3167 | } |
---|
3168 | |
---|
3169 | proc lpSickleDim(ideal G, list #) |
---|
3170 | "USAGE: lpSickleDim(G[,degbound,n]); G an ideal, degbound, n optional integers |
---|
3171 | RETURN: list |
---|
3172 | PURPOSE:Computing the K-dimension and the mistletoes |
---|
3173 | ASSUME: - basering is a Letterplace ring. |
---|
3174 | @* - if you specify a different degree bound degbound, |
---|
3175 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
3176 | NOTE: - If L is the list returned, then L[1] is an integer, the K-dimension, |
---|
3177 | @* L[2] is an ideal, the mistletoes. |
---|
3178 | @* - If degbound is set, there will be a degree bound added. 0 means no |
---|
3179 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
3180 | @* - n is the number of variables, which can be set to a different number. |
---|
3181 | @* Default: attrib(basering, lV). |
---|
3182 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
3183 | EXAMPLE: example lpSickleDim; shows examples |
---|
3184 | " |
---|
3185 | {int degbound = attrib(basering,"uptodeg");int n = attrib(basering, "lV"); |
---|
3186 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
3187 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
3188 | list L; |
---|
3189 | L = lp2ivId(normalize(lead(G))); |
---|
3190 | L = ivSickleDim(L,n,degbound); |
---|
3191 | L[2] = ivL2lpI(L[2]); |
---|
3192 | return(L); |
---|
3193 | } |
---|
3194 | example |
---|
3195 | { |
---|
3196 | "EXAMPLE:"; echo = 2; |
---|
3197 | ring r = 0,(x,y),dp; |
---|
3198 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
3199 | setring R; // sets basering to Letterplace ring |
---|
3200 | ideal G = x(1)*x(2), y(1)*y(2),x(1)*y(2)*x(3); // ideal G contains a |
---|
3201 | //Groebner basis |
---|
3202 | lpSickleDim(G); // invokes the procedure with ring parameters |
---|
3203 | // the factor algebra is finite, so the degree bound given by the Letterplace |
---|
3204 | // ring is not necessary |
---|
3205 | lpSickleDim(G,0); // procedure without any degree bound |
---|
3206 | } |
---|
3207 | |
---|
3208 | proc lpSickleHil(ideal G, list #) |
---|
3209 | "USAGE: lpSickleHil(G); |
---|
3210 | RETURN: list |
---|
3211 | PURPOSE:Computing the Hilbert series and the mistletoes |
---|
3212 | ASSUME: - basering is a Letterplace ring. |
---|
3213 | @* - if you specify a different degree bound degbound, |
---|
3214 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
3215 | NOTE: - If L is the list returned, then L[1] is an intvec, corresponding to the |
---|
3216 | @* Hilbert series, L[2] is an ideal, the mistletoes. |
---|
3217 | @* - If degbound is set, there will be a degree bound added. 0 means no |
---|
3218 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
3219 | @* - n is the number of variables, which can be set to a different number. |
---|
3220 | @* Default: attrib(basering, lV). |
---|
3221 | @* - If I = L[1] is the intvec returned, then I[k] is the (k-1)-th |
---|
3222 | @* coefficient of the Hilbert series. |
---|
3223 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
3224 | EXAMPLE: example lpSickleHil; shows examples |
---|
3225 | " |
---|
3226 | {int degbound = attrib(basering,"uptodeg");int n = attrib(basering, "lV"); |
---|
3227 | if (size(#) > 0){if (typeof(#[1])=="int"){if (#[1] >= 0){degbound = #[1];}}} |
---|
3228 | if (size(#) > 1){if (typeof(#[1])=="int"){if (#[2] > 0){n = #[2];}}} |
---|
3229 | list L; |
---|
3230 | L = lp2ivId(normalize(lead(G))); |
---|
3231 | L = ivSickleHil(L,n,degbound); |
---|
3232 | L[2] = ivL2lpI(L[2]); |
---|
3233 | return(L); |
---|
3234 | } |
---|
3235 | example |
---|
3236 | { |
---|
3237 | "EXAMPLE:"; echo = 2; |
---|
3238 | ring r = 0,(x,y),dp; |
---|
3239 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
3240 | setring R; // sets basering to Letterplace ring |
---|
3241 | ideal G = x(1)*x(2), y(1)*y(2),x(1)*y(2)*x(3); // ideal G contains a |
---|
3242 | //Groebner basis |
---|
3243 | lpSickleHil(G); // invokes the procedure with ring parameters |
---|
3244 | // the factor algebra is finite, so the degree bound given by the Letterplace |
---|
3245 | // ring is not necessary |
---|
3246 | lpSickleHil(G,0); // procedure without any degree bound |
---|
3247 | } |
---|
3248 | |
---|
3249 | proc sickle(ideal G, list #) |
---|
3250 | "USAGE: sickle(G[,m, d, h, degbound]); G an ideal; m,d,h,degbound optional |
---|
3251 | @* integers |
---|
3252 | RETURN: list |
---|
3253 | PURPOSE:Allowing the user to access all procs with one command |
---|
3254 | ASSUME: - basering is a Letterplace ring. |
---|
3255 | @* - if you specify a different degree bound degbound, |
---|
3256 | @* degbound <= attrib(basering,uptodeg) holds. |
---|
3257 | NOTE: The returned object will always be a list, but the entries of the |
---|
3258 | @* returned list may be very different |
---|
3259 | @* case m=1,d=1,h=1: see lpDHilbertSickle |
---|
3260 | @* case m=1,d=1,h=0: see lpSickleDim |
---|
3261 | @* case m=1,d=0,h=1: see lpSickleHil |
---|
3262 | @* case m=1,d=0,h=0: see lpSickle (this is the default case) |
---|
3263 | @* case m=0,d=1,h=1: see lpDHilbert |
---|
3264 | @* case m=0,d=1,h=0: see lpKDim |
---|
3265 | @* case m=0,d=0,h=1: see lpHilbert |
---|
3266 | @* case m=0,d=0,h=0: returns an error |
---|
3267 | @* - If degbound is set, there will be a degree bound added. 0 means no |
---|
3268 | @* degree bound. Default: attrib(basering,uptodeg). |
---|
3269 | @* - If the K-dimension is known to be infinite, a degree bound is needed |
---|
3270 | EXAMPLE: example sickle; shows examples |
---|
3271 | " |
---|
3272 | {int m,d,h,degbound; |
---|
3273 | m = 1; d = 0; h = 0; degbound = attrib(basering,"uptodeg"); |
---|
3274 | if (size(#) > 0) {if (typeof(#[1])=="int"){if (#[1] < 1) {m = 0;}}} |
---|
3275 | if (size(#) > 1) {if (typeof(#[1])=="int"){if (#[2] > 0) {d = 1;}}} |
---|
3276 | if (size(#) > 2) {if (typeof(#[1])=="int"){if (#[3] > 0) {h = 1;}}} |
---|
3277 | if (size(#) > 3) {if (typeof(#[1])=="int"){if (#[4] >= 0) {degbound = #[4];}}} |
---|
3278 | if (m == 1) |
---|
3279 | {if (d == 0) |
---|
3280 | {if (h == 0) {return(lpSickle(G,degbound,attrib(basering,"lV")));} |
---|
3281 | else {return(lpSickleHil(G,degbound,attrib(basering,"lV")));} |
---|
3282 | } |
---|
3283 | else |
---|
3284 | {if (h == 0) {return(lpSickleDim(G,degbound,attrib(basering,"lV")));} |
---|
3285 | else {return(lpDHilbertSickle(G,degbound,attrib(basering,"lV")));} |
---|
3286 | } |
---|
3287 | } |
---|
3288 | else |
---|
3289 | {if (d == 0) |
---|
3290 | {if (h == 0) {ERROR("You request to do nothing, so relax and do so");} |
---|
3291 | else {return(lpHilbert(G,degbound,attrib(basering,"lV")));} |
---|
3292 | } |
---|
3293 | else |
---|
3294 | {if (h == 0) {return(lpKDim(G,degbound,attrib(basering,"lV")));} |
---|
3295 | else {return(lpDHilbert(G,degbound,attrib(basering,"lV")));} |
---|
3296 | } |
---|
3297 | } |
---|
3298 | } |
---|
3299 | example |
---|
3300 | { |
---|
3301 | "EXAMPLE:"; echo = 2; |
---|
3302 | ring r = 0,(x,y),dp; |
---|
3303 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
3304 | setring R; // sets basering to Letterplace ring |
---|
3305 | ideal G = x(1)*x(2), y(1)*y(2),x(1)*y(2)*x(3); |
---|
3306 | // G contains a Groebner basis |
---|
3307 | sickle(G,1,1,1); // computes mistletoes, K-dimension and the Hilbert series |
---|
3308 | sickle(G,1,0,0); // computes mistletoes only |
---|
3309 | sickle(G,0,1,0); // computes K-dimension only |
---|
3310 | sickle(G,0,0,1); // computes Hilbert series only |
---|
3311 | } |
---|
3312 | |
---|
3313 | /////////////////////////////////////////////////////////////////////////////// |
---|
3314 | /* vl: new stuff for conversion to Magma and to SD |
---|
3315 | todo: doc, example |
---|
3316 | */ |
---|
3317 | proc extractVars(r) |
---|
3318 | { |
---|
3319 | int i = 1; |
---|
3320 | int j = 1; |
---|
3321 | string candidate; |
---|
3322 | list result = list(); |
---|
3323 | for (i = 1; i<=nvars(r);i++) |
---|
3324 | { |
---|
3325 | candidate = string(var(i))[1,find(string(var(i)),"(")-1]; |
---|
3326 | if (!inList(result, candidate)) |
---|
3327 | { |
---|
3328 | result = insert(result,candidate,size(result)); |
---|
3329 | } |
---|
3330 | } |
---|
3331 | return(result); |
---|
3332 | } |
---|
3333 | |
---|
3334 | proc letterPlacePoly2MagmaString(poly h) |
---|
3335 | { |
---|
3336 | int pos; |
---|
3337 | string s = string(h); |
---|
3338 | while(find(s,"(")) |
---|
3339 | { |
---|
3340 | pos = find(s,"("); |
---|
3341 | while(s[pos]!=")") |
---|
3342 | { |
---|
3343 | s = s[1,pos-1]+s[pos+1,size(s)-pos]; |
---|
3344 | } |
---|
3345 | if (size(s)!=pos) |
---|
3346 | { |
---|
3347 | s = s[1,pos-1]+s[pos+1,size(s)-pos]; // The last (")") |
---|
3348 | } |
---|
3349 | else |
---|
3350 | { |
---|
3351 | s = s[1,pos-1]; |
---|
3352 | } |
---|
3353 | } |
---|
3354 | return(s); |
---|
3355 | } |
---|
3356 | |
---|
3357 | proc letterPlaceIdeal2SD(ideal I, int upToDeg) |
---|
3358 | { |
---|
3359 | int i; |
---|
3360 | print("Don't forget to fill in the formal Data in the file"); |
---|
3361 | string result = "<?xml version=\"1.0\"?>"+newline+"<FREEALGEBRA createdAt=\"\" createdBy=\"Singular\" id=\"FREEALGEBRA/\">"+newline; |
---|
3362 | result = result + "<vars>"+string(extractVars(basering))+"</vars>"+newline; |
---|
3363 | result = result + "<basis>"+newline; |
---|
3364 | for (i = 1;i<=size(I);i++) |
---|
3365 | { |
---|
3366 | result = result + "<poly>"+letterPlacePoly2MagmaString(I[i])+"</poly>"+newline; |
---|
3367 | } |
---|
3368 | result = result + "</basis>"+newline; |
---|
3369 | result = result + "<uptoDeg>"+ string(upToDeg)+"</uptoDeg>"+newline; |
---|
3370 | result = result + "<Comment></Comment>"+newline; |
---|
3371 | result = result + "<Version></Version>"+newline; |
---|
3372 | result = result + "</FREEALGEBRA>"; |
---|
3373 | return(result); |
---|
3374 | } |
---|
3375 | |
---|
3376 | |
---|
3377 | /////////////////////////////////////////////////////////////////////////////// |
---|
3378 | |
---|
3379 | |
---|
3380 | proc tst_fpadim() |
---|
3381 | { |
---|
3382 | example ivDHilbert; |
---|
3383 | example ivDHilbertSickle; |
---|
3384 | example ivDimCheck; |
---|
3385 | example ivHilbert; |
---|
3386 | example ivKDim; |
---|
3387 | example ivMis2Base; |
---|
3388 | example ivMis2Dim; |
---|
3389 | example ivOrdMisLex; |
---|
3390 | example ivSickle; |
---|
3391 | example ivSickleHil; |
---|
3392 | example ivSickleDim; |
---|
3393 | example lpDHilbert; |
---|
3394 | example lpDHilbertSickle; |
---|
3395 | example lpHilbert; |
---|
3396 | example lpDimCheck; |
---|
3397 | example lpKDim; |
---|
3398 | example lpMis2Base; |
---|
3399 | example lpMis2Dim; |
---|
3400 | example lpOrdMisLex; |
---|
3401 | example lpSickle; |
---|
3402 | example lpSickleHil; |
---|
3403 | example lpSickleDim; |
---|
3404 | example sickle; |
---|
3405 | example ivL2lpI; |
---|
3406 | example iv2lp; |
---|
3407 | example iv2lpList; |
---|
3408 | example iv2lpMat; |
---|
3409 | example lp2iv; |
---|
3410 | example lp2ivId; |
---|
3411 | example lpId2ivLi; |
---|
3412 | example lpGkDim; |
---|
3413 | example lpGlDimBound; |
---|
3414 | example lpSubstitute; |
---|
3415 | } |
---|
3416 | |
---|
3417 | |
---|
3418 | /*proc lpSubstituteExpandRing(poly f, list s1, list s2) {*/ |
---|
3419 | /*int minDegBound = calcSubstDegBound(f,s1,s2);*/ |
---|
3420 | /**/ |
---|
3421 | /*def R = basering; // curr lp ring*/ |
---|
3422 | /*setring ORIGINALRING; // non lp ring TODO*/ |
---|
3423 | /*def R1 = makeLetterplaceRing(minDegBound);*/ |
---|
3424 | /*setring R1;*/ |
---|
3425 | /**/ |
---|
3426 | /*poly g = lpSubstitute(imap(R,f), imap(R,s1), imap(R,s2));*/ |
---|
3427 | /**/ |
---|
3428 | /*return (R1); // return the new ring*/ |
---|
3429 | /*}*/ |
---|
3430 | |
---|
3431 | proc lpSubstitute(poly f, ideal s1, ideal s2, list #) |
---|
3432 | "USAGE: lpSubstitute(f,s1,s2[,G]); f letterplace polynomial, s1 list (ideal) of variables |
---|
3433 | @* to replace, s2 list (ideal) of polynomials to replace with, G optional ideal to |
---|
3434 | @* reduce with. |
---|
3435 | RETURN: poly, the substituted polynomial |
---|
3436 | ASSUME: - basering is a Letterplace ring |
---|
3437 | @* - G is a groebner basis, |
---|
3438 | @* - the current ring has a sufficient degbound (can be calculated with |
---|
3439 | @* calcSubstDegBound()) |
---|
3440 | EXAMPLE: example lpSubstitute; shows examples |
---|
3441 | " |
---|
3442 | { |
---|
3443 | ideal G; |
---|
3444 | if (size(#) > 0) { |
---|
3445 | if (typeof(#[1])=="ideal") { |
---|
3446 | G = #[1]; |
---|
3447 | } |
---|
3448 | } |
---|
3449 | |
---|
3450 | poly fs; |
---|
3451 | for (int i = 1; i <= size(f); i++) { |
---|
3452 | poly fis = leadcoef(f[i]); |
---|
3453 | intvec ivfi = lp2iv(f[i]); |
---|
3454 | for (int j = 1; j <= size(ivfi); j++) { |
---|
3455 | int varindex = ivfi[j]; |
---|
3456 | int subindex = lpIndexOf(s1, var(varindex)); |
---|
3457 | if (subindex > 0) { |
---|
3458 | s2[subindex] = lpNF(s2[subindex],G); |
---|
3459 | fis = lpMult(fis, s2[subindex]); |
---|
3460 | } else { |
---|
3461 | fis = lpMult(fis, lpNF(iv2lp(varindex),G)); |
---|
3462 | } |
---|
3463 | /*fis = lpNF(fis,G);*/ |
---|
3464 | } |
---|
3465 | fs = fs + fis; |
---|
3466 | } |
---|
3467 | fs = lpNF(fs, G); |
---|
3468 | return (fs); |
---|
3469 | } |
---|
3470 | example { |
---|
3471 | LIB "fpadim.lib"; |
---|
3472 | ring r = 0,(x,y,z),dp; |
---|
3473 | def R = makeLetterplaceRing(4); |
---|
3474 | setring R; |
---|
3475 | |
---|
3476 | ideal G = x(1)*y(2); // optional |
---|
3477 | |
---|
3478 | poly f = 3*x(1)*x(2)+y(1)*x(2); |
---|
3479 | ideal s1 = x(1), y(1); |
---|
3480 | ideal s2 = y(1)*z(2)*z(3), x(1); |
---|
3481 | |
---|
3482 | // the substitution probably needs a higher degbound |
---|
3483 | int minDegBound = calcSubstDegBounds(f,s1,s2); |
---|
3484 | setring r; |
---|
3485 | def R1 = makeLetterplaceRing(minDegBound); |
---|
3486 | setring R1; |
---|
3487 | |
---|
3488 | // the last parameter is optional |
---|
3489 | lpSubstitute(imap(R,f), imap(R,s1), imap(R,s2), imap(R,G)); |
---|
3490 | } |
---|
3491 | example { |
---|
3492 | LIB "fpadim.lib"; |
---|
3493 | ring r = 0,(x,y,z),dp; |
---|
3494 | def R = makeLetterplaceRing(4); |
---|
3495 | setring R; |
---|
3496 | |
---|
3497 | poly f = 3*x(1)*x(2)+y(1)*x(2); |
---|
3498 | poly g = z(1)*x(2)+y(1); |
---|
3499 | poly h = 7*x(1)*z(2)+x(1); |
---|
3500 | ideal I = f,g,h; |
---|
3501 | ideal s1 = x(1), y(1); |
---|
3502 | ideal s2 = y(1)*z(2)*z(3), x(1); |
---|
3503 | |
---|
3504 | int minDegBound = calcSubstDegBounds(I,s1,s2); |
---|
3505 | setring r; |
---|
3506 | def R1 = makeLetterplaceRing(minDegBound); |
---|
3507 | setring R1; |
---|
3508 | |
---|
3509 | ideal I = imap(R,I); |
---|
3510 | ideal s1 = imap(R,s1); |
---|
3511 | ideal s2 = imap(R,s2); |
---|
3512 | for (int i = 1; i <= size(I); i++) { |
---|
3513 | lpSubstitute(I[i], s1, s2); |
---|
3514 | } |
---|
3515 | } |
---|
3516 | |
---|
3517 | static proc lpIndexOf(ideal I, poly p) { |
---|
3518 | for (int i = 1; i <= size(I); i++) { |
---|
3519 | if (I[i] == p) { |
---|
3520 | return (i); |
---|
3521 | } |
---|
3522 | } |
---|
3523 | return (-1); |
---|
3524 | } |
---|
3525 | |
---|
3526 | static proc ivIndexOf(list L, intvec iv) { |
---|
3527 | for (int i = 1; i <= size(L); i++) { |
---|
3528 | if (L[i] == iv) { |
---|
3529 | return (i); |
---|
3530 | } |
---|
3531 | } |
---|
3532 | return (-1); |
---|
3533 | } |
---|
3534 | |
---|
3535 | |
---|
3536 | proc calcSubstDegBound(poly f, ideal s1, ideal s2) |
---|
3537 | "USAGE: calcSubstDegBound(f,s1,s2); f letterplace polynomial, s1 list (ideal) of variables |
---|
3538 | @* to replace, s2 list (ideal) of polynomials to replace with |
---|
3539 | RETURN: int, the min degbound required to perform the substitution |
---|
3540 | ASSUME: - basering is a Letterplace ring |
---|
3541 | EXAMPLE: example lpSubstitute; shows examples |
---|
3542 | " |
---|
3543 | { |
---|
3544 | int maxDegBound = 0; |
---|
3545 | for (int i = 1; i <= size(f); i++) { |
---|
3546 | intvec ivfi = lp2iv(f[i]); |
---|
3547 | int tmpDegBound; |
---|
3548 | for (int j = 1; j <= size(ivfi); j++) { |
---|
3549 | int varindex = ivfi[j]; |
---|
3550 | int subindex = lpIndexOf(s1, var(varindex)); |
---|
3551 | if (subindex > 0) { |
---|
3552 | tmpDegBound = tmpDegBound + deg(s2[subindex]); |
---|
3553 | } else { |
---|
3554 | tmpDegBound = tmpDegBound + 1; |
---|
3555 | } |
---|
3556 | } |
---|
3557 | if (tmpDegBound > maxDegBound) { |
---|
3558 | maxDegBound = tmpDegBound; |
---|
3559 | } |
---|
3560 | } |
---|
3561 | |
---|
3562 | // increase degbound by 50% when ideal is provided |
---|
3563 | // needed for lpNF |
---|
3564 | maxDegBound = maxDegBound + maxDegBound/2; |
---|
3565 | |
---|
3566 | return (maxDegBound); |
---|
3567 | } |
---|
3568 | |
---|
3569 | // convenience method |
---|
3570 | proc calcSubstDegBounds(ideal I, ideal s1, ideal s2) |
---|
3571 | "USAGE: calcSubstDegBounds(I,s1,s2); I list (ideal) of letterplace polynomials, s1 list (ideal) |
---|
3572 | @* of variables to replace, s2 list (ideal) of polynomials to replace with |
---|
3573 | RETURN: int, the min degbound required to perform all of the substitutions |
---|
3574 | ASSUME: - basering is a Letterplace ring |
---|
3575 | EXAMPLE: example lpSubstitute; shows examples |
---|
3576 | " |
---|
3577 | { |
---|
3578 | int maxDegBound = 0; |
---|
3579 | for (int i = 1; i <= size(I); i++) { |
---|
3580 | int tmpDegBound = calcSubstDegBound(I[i], s1, s2, #); |
---|
3581 | if (tmpDegBound > maxDegBound) { |
---|
3582 | maxDegBound = tmpDegBound; |
---|
3583 | } |
---|
3584 | } |
---|
3585 | return (maxDegBound); |
---|
3586 | } |
---|
3587 | |
---|
3588 | |
---|
3589 | /* |
---|
3590 | Here are some examples one may try. Just copy them into your console. |
---|
3591 | These are relations for braid groups, up to degree d: |
---|
3592 | |
---|
3593 | |
---|
3594 | LIB "fpadim.lib"; |
---|
3595 | ring r = 0,(x,y,z),dp; |
---|
3596 | int d =10; // degree |
---|
3597 | def R = makeLetterplaceRing(d); |
---|
3598 | setring R; |
---|
3599 | ideal I = y(1)*x(2)*y(3) - z(1)*y(2)*z(3), x(1)*y(2)*x(3) - z(1)*x(2)*y(3), |
---|
3600 | z(1)*x(2)*z(3) - y(1)*z(2)*x(3), x(1)*x(2)*x(3) + y(1)*y(2)*y(3) + |
---|
3601 | z(1)*z(2)*z(3) + x(1)*y(2)*z(3); |
---|
3602 | option(prot); |
---|
3603 | option(redSB);option(redTail);option(mem); |
---|
3604 | ideal J = system("freegb",I,d,3); |
---|
3605 | lpDimCheck(J); |
---|
3606 | sickle(J,1,1,1,d);//Computes mistletoes, K-dimension and the Hilbert series |
---|
3607 | |
---|
3608 | |
---|
3609 | |
---|
3610 | LIB "fpadim.lib"; |
---|
3611 | ring r = 0,(x,y,z),dp; |
---|
3612 | int d =11; // degree |
---|
3613 | def R = makeLetterplaceRing(d); |
---|
3614 | setring R; |
---|
3615 | ideal I = y(1)*x(2)*y(3) - z(1)*y(2)*z(3), x(1)*y(2)*z(3) - z(1)*x(2)*y(3), |
---|
3616 | z(1)*x(2)*z(3) - y(1)*z(2)*x(3), x(1)*x(2)*x(3) + y(1)*y(2)*y(3) + |
---|
3617 | z(1)*z(2)*z(3) + x(1)*y(2)*z(3); |
---|
3618 | option(prot); |
---|
3619 | option(redSB);option(redTail);option(mem); |
---|
3620 | ideal J = system("freegb",I,d,3); |
---|
3621 | lpDimCheck(J); |
---|
3622 | sickle(J,1,1,1,d); |
---|
3623 | |
---|
3624 | |
---|
3625 | |
---|
3626 | LIB "fpadim.lib"; |
---|
3627 | ring r = 0,(x,y,z),dp; |
---|
3628 | int d = 6; // degree |
---|
3629 | def R = makeLetterplaceRing(d); |
---|
3630 | setring R; |
---|
3631 | ideal I = y(1)*x(2)*y(3) - z(1)*y(2)*z(3), x(1)*y(2)*x(3) - z(1)*x(2)*y(3), |
---|
3632 | z(1)*x(2)*z(3) - y(1)*z(2)*x(3), x(1)*x(2)*x(3) -2*y(1)*y(2)*y(3) + 3*z(1)*z(2)*z(3) -4*x(1)*y(2)*z(3) + 5*x(1)*z(2)*z(3)- 6*x(1)*y(2)*y(3) +7*x(1)*x(2)*z(3) - 8*x(1)*x(2)*y(3); |
---|
3633 | option(prot); |
---|
3634 | option(redSB);option(redTail);option(mem); |
---|
3635 | ideal J = system("freegb",I,d,3); |
---|
3636 | lpDimCheck(J); |
---|
3637 | sickle(J,1,1,1,d); |
---|
3638 | */ |
---|
3639 | |
---|
3640 | /* |
---|
3641 | Here are some examples, which can also be found in [studzins]: |
---|
3642 | |
---|
3643 | // takes up to 880Mb of memory |
---|
3644 | LIB "fpadim.lib"; |
---|
3645 | ring r = 0,(x,y,z),dp; |
---|
3646 | int d =10; // degree |
---|
3647 | def R = makeLetterplaceRing(d); |
---|
3648 | setring R; |
---|
3649 | ideal I = |
---|
3650 | z(1)*z(2)*z(3)*z(4) + y(1)*x(2)*y(3)*x(4) - x(1)*y(2)*y(3)*x(4) - 3*z(1)*y(2)*x(3)*z(4), x(1)*x(2)*x(3) + y(1)*x(2)*y(3) - x(1)*y(2)*x(3), z(1)*y(2)*x(3)-x(1)*y(2)*z(3) + z(1)*x(2)*z(3); |
---|
3651 | option(prot); |
---|
3652 | option(redSB);option(redTail);option(mem); |
---|
3653 | ideal J = system("freegb",I,d,nvars(r)); |
---|
3654 | lpDimCheck(J); |
---|
3655 | sickle(J,1,1,1,d); // dimension is 24872 |
---|
3656 | |
---|
3657 | |
---|
3658 | LIB "fpadim.lib"; |
---|
3659 | ring r = 0,(x,y,z),dp; |
---|
3660 | int d =10; // degree |
---|
3661 | def R = makeLetterplaceRing(d); |
---|
3662 | setring R; |
---|
3663 | ideal I = x(1)*y(2) + y(1)*z(2), x(1)*x(2) + x(1)*y(2) - y(1)*x(2) - y(1)*y(2); |
---|
3664 | option(prot); |
---|
3665 | option(redSB);option(redTail);option(mem); |
---|
3666 | ideal J = system("freegb",I,d,3); |
---|
3667 | lpDimCheck(J); |
---|
3668 | sickle(J,1,1,1,d); |
---|
3669 | */ |
---|
3670 | |
---|
3671 | |
---|
3672 | /* |
---|
3673 | Example for computing GK dimension: |
---|
3674 | returns a ring which contains an ideal I |
---|
3675 | run gkDim(I) inside this ring and it should return 2n (the GK dimension |
---|
3676 | of n-th Weyl algebra including evaluation operators). |
---|
3677 | |
---|
3678 | proc createWeylEx(int n, int d) |
---|
3679 | " |
---|
3680 | " |
---|
3681 | { |
---|
3682 | int baseringdef; |
---|
3683 | if (defined(basering)) // if a basering is defined, it should be saved for later use |
---|
3684 | { |
---|
3685 | def save = basering; |
---|
3686 | baseringdef = 1; |
---|
3687 | } |
---|
3688 | ring r = 0,(d(1..n),x(1..n),e(1..n)),dp; |
---|
3689 | def R = makeLetterplaceRing(d); |
---|
3690 | setring R; |
---|
3691 | ideal I; int i,j; |
---|
3692 | |
---|
3693 | for (i = 1; i <= n; i++) |
---|
3694 | { |
---|
3695 | for (j = i+1; j<= n; j++) |
---|
3696 | { |
---|
3697 | I[size(I)+1] = lpMult(var(i),var(j)); |
---|
3698 | } |
---|
3699 | } |
---|
3700 | |
---|
3701 | for (i = 1; i <= n; i++) |
---|
3702 | { |
---|
3703 | for (j = i+1; j<= n; j++) |
---|
3704 | { |
---|
3705 | I[size(I)+1] = lpMult(var(n+i),var(n+j)); |
---|
3706 | } |
---|
3707 | } |
---|
3708 | for (i = 1; i <= n; i++) |
---|
3709 | { |
---|
3710 | for (j = 1; j<= n; j++) |
---|
3711 | { |
---|
3712 | I[size(I)+1] = lpMult(var(i),var(n+j)); |
---|
3713 | } |
---|
3714 | } |
---|
3715 | for (i = 1; i <= n; i++) |
---|
3716 | { |
---|
3717 | for (j = 1; j<= n; j++) |
---|
3718 | { |
---|
3719 | I[size(I)+1] = lpMult(var(i),var(2*n+j)); |
---|
3720 | } |
---|
3721 | } |
---|
3722 | for (i = 1; i <= n; i++) |
---|
3723 | { |
---|
3724 | for (j = 1; j<= n; j++) |
---|
3725 | { |
---|
3726 | I[size(I)+1] = lpMult(var(2*n+i),var(n+j)); |
---|
3727 | } |
---|
3728 | } |
---|
3729 | for (i = 1; i <= n; i++) |
---|
3730 | { |
---|
3731 | for (j = 1; j<= n; j++) |
---|
3732 | { |
---|
3733 | I[size(I)+1] = lpMult(var(2*n+i),var(2*n+j)); |
---|
3734 | } |
---|
3735 | } |
---|
3736 | I = simplify(I,2+4); |
---|
3737 | I = letplaceGBasis(I); |
---|
3738 | export(I); |
---|
3739 | if (baseringdef == 1) {setring save;} |
---|
3740 | return(R); |
---|
3741 | } |
---|
3742 | |
---|
3743 | proc TestGKAuslander3() |
---|
3744 | { |
---|
3745 | ring r = (0,q),(z,x,y),(dp(1),dp(2)); |
---|
3746 | def R = makeLetterplaceRing(5); // constructs a Letterplace ring |
---|
3747 | R; setring R; // sets basering to Letterplace ring |
---|
3748 | ideal I; |
---|
3749 | I = q*x(1)*y(2) - y(1)*x(2), z(1)*y(2) - y(1)*z(2), z(1)*x(2) - x(1)*z(2); |
---|
3750 | I = letplaceGBasis(I); |
---|
3751 | lpGkDim(I); // must be 3 |
---|
3752 | I = x(1)*y(2)*z(3) - y(1)*x(2), z(1)*y(2) - y(1)*z(2), z(1)*x(2) - x(1)*z(2);//gkDim = 2 |
---|
3753 | I = letplaceGBasis(I); // not finite BUT contains a poly in x,y only |
---|
3754 | lpGkDim(I); // must be 4 |
---|
3755 | |
---|
3756 | ring r = 0,(y,x,z),dp; |
---|
3757 | def R = makeLetterplaceRing(10); // constructs a Letterplace ring |
---|
3758 | R; setring R; // sets basering to Letterplace ring |
---|
3759 | ideal I; |
---|
3760 | I = x(1)*y(2)*z(3) - y(1)*x(2), z(1)*y(2) - y(1)*z(2), z(1)*x(2) - x(1)*z(2);//gkDim = 2 |
---|
3761 | I = letplaceGBasis(I); // computed as it would be homogenized; infinite |
---|
3762 | poly p = x(1)*y(2)*y(3)*x(4)-y(1)*x(2)*x(3)*y(4); |
---|
3763 | lpNF(p, I); // 0 as expected |
---|
3764 | |
---|
3765 | // with inverse of z |
---|
3766 | ring r = 0,(iz,z,x,y),dp; |
---|
3767 | def R = makeLetterplaceRing(11); // constructs a Letterplace ring |
---|
3768 | R; setring R; // sets basering to Letterplace ring |
---|
3769 | ideal I; |
---|
3770 | I = x(1)*y(2)*z(3) - y(1)*x(2), z(1)*y(2) - y(1)*z(2), z(1)*x(2) - x(1)*z(2), |
---|
3771 | iz(1)*y(2) - y(1)*iz(2), iz(1)*x(2) - x(1)*iz(2), iz(1)*z(2)-1, z(1)*iz(2) -1; |
---|
3772 | I = letplaceGBasis(I); // |
---|
3773 | setring r; |
---|
3774 | def R2 = makeLetterplaceRing(23); // constructs a Letterplace ring |
---|
3775 | setring R2; // sets basering to Letterplace ring |
---|
3776 | ideal I = imap(R,I); |
---|
3777 | lpGkDim(I); |
---|
3778 | |
---|
3779 | |
---|
3780 | ring r = 0,(t,z,x,y),(dp(2),dp(2)); |
---|
3781 | def R = makeLetterplaceRing(20); // constructs a Letterplace ring |
---|
3782 | R; setring R; // sets basering to Letterplace ring |
---|
3783 | ideal I; |
---|
3784 | I = x(1)*y(2)*z(3) - y(1)*x(2)*t(3), z(1)*y(2) - y(1)*z(2), z(1)*x(2) - x(1)*z(2), |
---|
3785 | t(1)*y(2) - y(1)*t(2), t(1)*x(2) - x(1)*t(2), t(1)*z(2) - z(1)*t(2);//gkDim = 2 |
---|
3786 | I = letplaceGBasis(I); // computed as it would be homogenized; infinite |
---|
3787 | LIB "elim.lib"; |
---|
3788 | ideal Inoz = nselect(I,intvec(2,6,10,14,18,22,26,30)); |
---|
3789 | for(int i=1; i<=20; i++) |
---|
3790 | { |
---|
3791 | Inoz=subst(Inoz,t(i),1); |
---|
3792 | } |
---|
3793 | ideal J = x(1)*y(2)*y(3)*x(4)-y(1)*x(2)*x(3)*y(4); |
---|
3794 | J = letplaceGBasis(J); |
---|
3795 | |
---|
3796 | poly p = x(1)*y(2)*y(3)*x(4)-y(1)*x(2)*x(3)*y(4); |
---|
3797 | lpNF(p, I); // 0 as expected |
---|
3798 | |
---|
3799 | ring r2 = 0,(x,y),dp; |
---|
3800 | def R2 = makeLetterplaceRing(50); // constructs a Letterplace ring |
---|
3801 | setring R2; |
---|
3802 | ideal J = x(1)*y(2)*y(3)*x(4)-y(1)*x(2)*x(3)*y(4); |
---|
3803 | J = letplaceGBasis(J); |
---|
3804 | } |
---|
3805 | |
---|
3806 | */ |
---|
3807 | |
---|
3808 | |
---|
3809 | /* actual work: |
---|
3810 | // downup algebra A |
---|
3811 | LIB "fpadim.lib"; |
---|
3812 | ring r = (0,a,b,g),(x,y),Dp; |
---|
3813 | def R = makeLetterplaceRing(6); // constructs a Letterplace ring |
---|
3814 | setring R; |
---|
3815 | poly F1 = g*x(1); |
---|
3816 | poly F2 = g*y(1); |
---|
3817 | ideal J = x(1)*x(2)*y(3)-a*x(1)*y(2)*x(3) - b*y(1)*x(2)*x(3) - F1, |
---|
3818 | x(1)*y(2)*y(3)-a*y(1)*x(2)*y(3) - b*y(1)*y(2)*x(3) - F2; |
---|
3819 | J = letplaceGBasis(J); |
---|
3820 | lpGkDim(J); // 3 == correct |
---|
3821 | |
---|
3822 | // downup algebra B |
---|
3823 | LIB "fpadim.lib"; |
---|
3824 | ring r = (0,a,b,g, p(1..7),q(1..7)),(x,y),Dp; |
---|
3825 | def R = makeLetterplaceRing(6); // constructs a Letterplace ring |
---|
3826 | setring R; |
---|
3827 | ideal imn = 1, y(1)*y(2)*y(3), x(1)*y(2), y(1)*x(2), x(1)*x(2), y(1)*y(2), x(1), y(1); |
---|
3828 | int i; |
---|
3829 | poly F1, F2; |
---|
3830 | for(i=1;i<=7;i++) |
---|
3831 | { |
---|
3832 | F1 = F1 + p(i)*imn[i]; |
---|
3833 | F2 = F2 + q(i)*imn[i]; |
---|
3834 | } |
---|
3835 | ideal J = x(1)*x(2)*y(3)-a*x(1)*y(2)*x(3) - b*y(1)*x(2)*x(3) - F1, |
---|
3836 | x(1)*y(2)*y(3)-a*y(1)*x(2)*y(3) - b*y(1)*y(2)*x(3) - F2; |
---|
3837 | J = letplaceGBasis(J); |
---|
3838 | lpGkDim(J); // 3 == correct |
---|
3839 | |
---|
3840 | */ |
---|