Changeset 6a07eb in git for Singular/LIB/dmodvar.lib
- Timestamp:
- Jul 22, 2010, 10:29:11 PM (13 years ago)
- Branches:
- (u'spielwiese', '0d6b7fcd9813a1ca1ed4220cfa2b104b97a0a003')
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- 40e810dce492e702bf0e751809ae911eaf670a12
- Parents:
- 237b3e4eb8747703701bf0ed61e0bbd289339b4a
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Singular/LIB/dmodvar.lib
r237b3e4 r6a07eb 9 9 Jorge Martin-Morales, jorge@unizar.es 10 10 11 THEORY: Let K be a field of characteristic 0. Given a polynomial ring 12 R = K[x_1,...,x_n] and a set of polynomial f_1,..., f_r in R, define 13 F = f_1 * ... * f_r and F^s:=f_1^s_1*...*f_r^s_r for symbolic discrete 14 (that is shiftable) variables s_1,..., s_r. 15 The module R[1/F]*F^s has a structure of a D<S>-module, where 16 D<S> := D(R) tensored with S over K, where 17 - D(R) is an n-th Weyl algebra K<x_1,...,x_n,d_1,...,d_n | d_j x_j = x_j d_j +1> 18 - S is the universal enveloping algebra of gl_r, generated by s_{ij}, where s_{ii}=s_i. 19 One is interested in the following data: 20 - the left ideal Ann F^s in D<S>, usually denoted by LD in the output 21 - global Bernstein polynomial in one variable s = s_1 + ...+ s_r, denoted by bs, 22 - its minimal integer root s0, the list of all roots of bs, which are known 23 to be rational, with their multiplicities, which is denoted by BS 24 - an r-tuple of operators in D<S>, denoted by PS, such that the functional equality 25 sum(k=1 to k=r) P_k*f_k*F^s = bs*F^s holds in R[1/F]*F^s. 11 THEORY: Let K be a field of characteristic 0. Given a polynomial ring R = K[x_1,...,x_n] and 12 @* a set of polynomial f_1,..., f_r in R, define F = f_1 * ... * f_r and F^s:=f_1^s_1*...*f_r^s_r 13 @* for symbolic discrete (that is shiftable) variables s_1,..., s_r. 14 @* The module R[1/F]*F^s has a structure of a D<S>-module, where D<S> := D(R) tensored with S over K, where 15 @* - D(R) is an n-th Weyl algebra K<x_1,...,x_n,d_1,...,d_n | d_j x_j = x_j d_j +1> 16 @* - S is the universal enveloping algebra of gl_r, generated by s_{ij}, where s_{ii}=s_i. 17 @* One is interested in the following data: 18 @* - the left ideal Ann F^s in D<S>, usually denoted by LD in the output 19 @* - global Bernstein polynomial in one variable s = s_1 + ...+ s_r, denoted by bs, 20 @* - its minimal integer root s0, the list of all roots of bs, which are known 21 @* to be negative rational numbers, with their multiplicities, which is denoted by BS 22 @* - an r-tuple of operators in D<S>, denoted by PS, such that the functional equality 23 @* sum(k=1 to k=r) P_k*f_k*F^s = bs*F^s holds in R[1/F]*F^s. 26 24 27 25 REFERENCES: … … 36 34 AUXILIARY PROCEDURES: 37 35 makeIF(F[,ORD]); create the Malgrange ideal, associated with F = F[1],..,F[P] 36 37 SEE ALSO: bfun_lib, dmod_lib, dmodapp_lib, gmssing_lib 38 39 KEYWORDS: D-module; D-module structure; Bernstein-Sato polynomial for variety; global Bernstein-Sato polynomial for variety; 40 Weyl algebra; parametric annihilator for variety; Budur-Mustata-Saito approach; initial ideal approach; 38 41 "; 39 42 … … 362 365 363 366 proc bfctVarAnn (ideal F, list #) 364 "USAGE: bfctVarAnn(F[,gid,eng]); F an ideal, gid,eng optional ints 365 RETURN: list of ideal and intvec 366 PURPOSE: computes the roots of the Bernstein-Sato polynomial and their 367 @* multiplicities for an affine algebraic variety defined by 368 @* F = F[1],..,F[r]. 367 "USAGE: bfctVarAnn(F[,gid,eng]); F an ideal, gid,eng optional ints 368 RETURN: list of an ideal and an intvec 369 PURPOSE: computes the roots of the Bernstein-Sato polynomial and their multiplicities 370 @* for an affine algebraic variety defined by F = F[1],..,F[r]. 369 371 ASSUME: The basering is a commutative polynomial ring in char 0. 370 372 BACKGROUND: In this proc, the annihilator of f^s in D[s] is computed and then a 371 373 @* system of linear equations is solved by linear reductions in order to 372 @* find the minimal polynomial of S = s(1)(1) + ... + s(P)(P), following 373 @* the ideas by Noro. 374 NOTE: In the output list, the ideal contains all the roots and the invec their 375 @* multiplicities. 374 @* find the minimal polynomial of S = s(1)(1) + ... + s(P)(P) 375 NOTE: In the output list, the ideal contains all the roots and the intvec their multiplicities. 376 376 @* If gid<>0, the ideal is used as given. Otherwise, and by default, a 377 377 @* heuristically better suited generating set is used.
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