GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
LoadPackage( "RingsForHomalg" ); LoadPackage( "Modules" ); R := HomalgFieldOfRationalsInDefaultCAS( ) * "x,y"; I := LeftSubmodule( "x", R ); J := LeftSubmodule( "y", R ); ## Cohen-Macaulay module with nonregular support M := 1 * R / ( I * J ); K := I + J; Assert( 0, Depth( K, M ) = 1 );