GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
LoadPackage( "RingsForHomalg" ); B1 := RingForHomalgInMapleUsingJanet( "[x]" ); Rskl := HomalgMatrix( "[ \ [ [[1,[x,x,x]], [a(x),[x,x]], [b(x),[x]], [c(x),[]]] ] \ ]", B1 ); Rsys := HomalgMatrix( "[ \ [ [[1,[x]]] , [[-1,[]]] , 0 ], \ [ 0 , [[1,[x]]] , [[-1,[]]] ], \ [ [[c(x),[]]] , [[b(x),[]]] , [[a(x),[]],[1,[x]]] ] \ ]", B1 ); LoadPackage( "Modules" ); Mskl := LeftPresentation( Rskl ); Msys := LeftPresentation( Rsys ); alpha := HomalgMatrix( "[ \ [ [[1,[]]] , 0 , 0 ] \ ]", B1 ); alpha := HomalgMap( alpha, Mskl, Msys ); delta := HomalgMatrix( "[ \ [ [[1,[x]]] ] \ ]", B1 ); delta := HomalgMap( delta, Mskl );