LoadPackage( "itc" ); F := FreeGroup( "a", "b", "c" ); a := F.1; b := F.2; c := F.3; rels := [ c^4 ]; G := F / rels; a := G.1; b := G.2; c := G.3; H := Subgroup( G, [ c ] ); InteractiveTC( G, H );