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7.5.18.0. ncHom
Procedure from library nchomolog.lib (see nchomolog_lib).
- Usage:
- ncHom(M,N); M,N modules
- Compute:
- A presentation of Hom(M',N'), M'=coker(M), N'=coker(N)
- Assume:
- M' is a left module, N' is a centralizing bimodule
- Note:
- ncHom(M,N) is a right module, hence a right presentation matrix
is returned
Example:
| | LIB "nchomolog.lib";
ring A=0,(x,y,z),dp;
matrix M[3][3]=1,2,3,
4,5,6,
7,8,9;
matrix N[2][2]=x,y,
z,0;
module H = ncHom(M,N);
print(H);
==> 0,0,0,0,y,x,
==> 0,0,0,z,0,z,
==> 1,0,0,0,0,0,
==> 0,1,0,0,0,0,
==> 0,0,2,1,0,0,
==> 0,0,1,0,0,0
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