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D.4.7.14 isReg

Procedure from library homolog.lib (see homolog_lib).

Usage:
isReg(I,M); I ideal, M module

Return:
1 if given (ordered) list of generators for I is coker(M)-sequence;
0 if this is not the case.

Example:
 
LIB "homolog.lib";
ring R = 0,(x,y,z),dp;
ideal I = x*(y-1),y,z*(y-1);
isReg(I,0);             // given list of generators is Q[x,y,z]-sequence
==> 1
I = x*(y-1),z*(y-1),y;  // change sorting of generators
isReg(I,0);
==> 0
ring r = 0,(x,y,z),ds;  // local ring
ideal I=fetch(R,I);
isReg(I,0);             // result independent of sorting of generators
==> 1