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D.15.23.10 isGroupHomomorphism

Procedure from library multigrading.lib (see multigrading_lib).

Usage:
isGoupHomomorphism(L1,L2,A); L1 and L2 are groups, A is an integer matrix

Purpose:
checks whether A defines a group homomorphism phi: L1 --> L2

Return:
int, 1 if A defines the homomorphism and 0 otherwise

Example:
 
LIB "multigrading.lib";
intmat L1[4][1]=
0,
0,
0,
2;
intmat L2[3][2]=
0, 0,
2, 0,
0, 3;
intmat A[3][4] =
1, 2, 3, 0,
7, 0, 0, 0,
1, 2, 0, 3;
print( A );
==>      1     2     3     0
==>      7     0     0     0
==>      1     2     0     3
isGroupHomomorphism(L1, L2, A);
==> 1
intmat B[3][4] =
1, 2, 3, 0,
7, 0, 0, 0,
1, 2, 0, 2;
print( B );
==>      1     2     3     0
==>      7     0     0     0
==>      1     2     0     2
isGroupHomomorphism(L1, L2, B); // Not a homomorphism!
==> 0