GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
LoadPackage( "RingsForHomalg" ); Qt := HomalgFieldOfRationalsInMaple( ) * "t"; A1 := RingOfDerivations( Qt, "D" ); Rskl := HomalgMatrix( "[ \ D^3 + a * D^2 + b * D + c \ ]", 1, 1, A1 ); Rsys := HomalgMatrix( "[ \ D, -1, 0, \ 0, D, -1, \ c, b, a+D \ ]", 3, 3, A1 ); LoadPackage( "Modules" ); Mskl := LeftPresentation( Rskl ); Msys := LeftPresentation( Rsys ); alpha := HomalgMatrix( "[ 1, 0, 0 ]", 1, 3, A1 ); alpha := HomalgMap( alpha, Mskl, Msys ); delta := HomalgMatrix( "[ D ]", 1, 1, A1 ); delta := HomalgMap( delta, Mskl );