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D.4.3.13 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 |