Changeset 8fc505d in git
- Timestamp:
- Oct 6, 2010, 9:19:00 AM (14 years ago)
- Branches:
- (u'spielwiese', 'fe61d9c35bf7c61f2b6cbf1b56e25e2f08d536cc')
- Children:
- 20aed372f6f3570345cfae02b1f372ebf5f1c0fa
- Parents:
- a1f90e40f6eb4bdcfaf9ef62b43cfc9c02f4f093
- File:
-
- 1 edited
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Singular/LIB/integralbasis.lib
ra1f90e4 r8fc505d 9 9 F. Seelisch, seelisch@mathematik.uni-kl.de 10 10 11 OVERVIEW: 12 Given an irreducible polynomial f in two variables defining a plane curve, 13 this library implements an algorithm to compute an integral basis of the 14 integral closure of the affine coordinate ring in the algebraic function 15 field via normalization.@* 16 The user can choose whether the algorithm will do the computation globally 17 or (this is the default) compute in the localization at each component of 18 the singular locus and put everything together. 19 11 20 PROCEDURES: 12 21 integralBasis(f, intVar); Integral basis of an algebraic function field … … 24 33 must be monic as polynomial in the intVar-th variable.@* 25 34 Optional parameters in list choose (can be entered in any order):@* 26 Algorithm:@*35 Parameters for selecting the algorithm:@* 27 36 - \"global\" -> computes the integral basis by computing the 28 37 normalization of R/<f>, where R is the base ring.@* … … 31 40 locus of R/<f>, and then putting everything together. 32 41 This is the default option.@* 33 Other :@*42 Other parameters:@* 34 43 - \"isIrred\" -> assumes that the input polynomial f is irreducible, 35 and therefore will not check it. If this option is given but f is not44 and therefore will not check this. If this option is given but f is not 36 45 irreducible, the output might be wrong.@* 37 46 - list(\"inputJ\", ideal inputJ) -> takes as initial test ideal the 38 47 ideal inputJ. This option is only for use in other procedures. Using 39 48 this option, the result might not be the integral basis.@* 40 (When this option is given the global option will be used.)@*49 (When this option is given, the global option will be used.)@* 41 50 - list(\"inputC\", ideal inputC) -> takes as initial conductor the 42 51 ideal inputC. This option is only for use in other procedures. Using 43 52 this option, the result might not be the integral basis.@* 44 (When this option is given the global option will be used.)@*53 (When this option is given, the global option will be used.)@* 45 54 RETURN: a list, say l, of size 2. 46 @formatl[1] is an ideal I and l[2] is a polynomial D such that the integral55 l[1] is an ideal I and l[2] is a polynomial D such that the integral 47 56 basis is b_0 = I[1] / D, b_1 = I[2] / D, ..., b_{n-1} = I[n] / D.@* 48 57 That is, the integral closure of k[x] in the algebraic function 49 58 field k(x,y) is @* 50 59 k[x] b_0 + k[x] b_1 + ... + k[x] b_{n-1},@* 51 where we assume that x is the tra scendental variable, y is the integral60 where we assume that x is the transcendental variable, y is the integral 52 61 element (indicated by intVar), f gives the integral equation and n is 53 62 the degree of f as a polynomial in y.@* 54 @end format 63 55 64 THEORY: We compute the integral basis of the integral closure of k[x] in k(x,y) 56 65 by computing the normalization of the affine ring k[x,y]/<f> and
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