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