GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
Read( "homalg.g" ); iota := TorsionObjectEmb( M ); pi := TorsionFreeFactorEpi( M ); C := HomalgComplex( pi ); Add( C, iota ); T := TorsionObject( M ); triangle := RHom( C, T ); lecs := LongSequence( triangle ); IsExactSequence( lecs ); Triangle := LTensorProduct( C, T ); lehs := LongSequence( Triangle ); IsExactSequence( lehs ); ByASmallerPresentation( lecs ); homalgResetFilters( lecs ); Assert( 0, IsExactSequence( lecs ) ); ByASmallerPresentation( lehs ); homalgResetFilters( lehs ); Assert( 0, IsExactSequence( lehs ) );