GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
Read( "Markus_Lokalisierung.g" ); filt := PurityFiltration( M ); II_E := SpectralSequence( filt ); m := IsomorphismOfFiltration( filt ); filtN := PurityFiltration( N ); n := IsomorphismOfFiltration( filtN );