GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
LoadPackage( "RingsForHomalg" ); R := HomalgFieldOfRationalsInDefaultCAS( ) * "x,y"; M := HomalgMatrix( "[x^3,y^3,x+y,x-y, y,x,x,y]", 2, 4, R ); LoadPackage( "Modules" ); M := LeftPresentation( M ); H := Hom( M, R ); # NrRelations( H );