|
 |
 |
 |
 |
 |
 |
 |
 |
 |
D.4.3.12 isLocallyFree
Procedure from library homolog.lib (see homolog_lib).
- Usage:
isLocallyFree(M,r); M module, r int
- Return:
1 if M’=coker(M) is locally free of constant rank r;
0 if this is not the case.
Example:
LIB "homolog.lib"; ring R=0,(x,y,z),dp; matrix M[2][3]; // the presentation matrix M=x-1,y-1,z,y-1,x-2,x; ideal I=fitting(M,0); // 0-th Fitting ideal of coker(M) qring Q=I; matrix M=fetch(R,M); isLocallyFree(M,1); // as R/I-module, coker(M) is locally free of rk 1 → 1 isLocallyFree(M,0); → 0 |