Hallo, s4 := Group((1,2,3,4),(1,2));; s3 := Group((1,2,3),(1,2));; hom := GroupHomomorphismByImages( s4 , s3, GeneratorsOfGroup(s4), [(1,2),(2,3)]; What is [(1,2),(2,3)] and how can I get this list in other examples? Best Regards Kurt Ewald