GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
Read( "Viktor.g" ); II_E := GrothendieckSpectralSequence( RightDualizingFunctor( A1 ), LeftDualizingFunctor( A1 ), V ); ByASmallerPresentation( II_E ); filt := FiltrationBySpectralSequence( II_E ); m := IsomorphismOfFiltration( filt );