I got structure description of all Subgroups of A:=DihedralGroup(8); as gap> List(A, StructureDescription); [ "1" ,"C2", "C2","C2","C2","C2","C2×C2","C4","C2×C2","D8" ] but i see that "C2" is repeated five times and "C2×C2" repeated twice. I need explanation on the above. Thanks.