1LoadPackage( "ModulePresentationsForCAP" );
2ZZ := HOMALG_MATRICES.ZZ;
3LeftPresentations( ZZ );
4RightPresentations( ZZ );
5A := HomalgMatrix( [ [ 1, 2 ], [ 2, 3 ] ], ZZ );
6Aleft := AsLeftPresentation( A );
7Aright := AsRightPresentation( A );
8B := HomalgMatrix( [ [ 1, 2 ] ], ZZ );
9Bleft := AsLeftPresentation( B );
10Bright := AsRightPresentation( B );
11tau := HomalgMatrix( [ [ 1, 0 ], [ 0, 1 ] ], ZZ );
12
13
14#########################
15##
16## Cokernel
17##
18#########################
19
20A := AsLeftPresentation( HomalgZeroMatrix( 0, 1, ZZ ) );
21phi := HomalgMatrix( [ [ 4 ] ], ZZ );
22
23phi := PresentationMorphism( A, phi, A );
24
25epsilon := CokernelProjection( phi );
26
27tau := HomalgMatrix( [ [ 2 ] ], ZZ );
28B := AsLeftPresentation( HomalgMatrix( [ [ 8 ] ], ZZ ) );
29tau := PresentationMorphism( A, tau, B );
30
31
32
33