GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
## Abelian.g Read( "ReducedBasisOfModule.g" ); ## abelian category: [HS, Prop. II.9.6] d := Resolution( W ); d2 := CertainMorphism( d, 2 ); C_coker := CokernelSequence( d2 ); C_ker := KernelSequence( d2 );