The PowerStructure of category GrpGPC.
The set of all subgroups of G. This is very useful when constructing sets of polycyclic groups. If the user will be building a set of subgroups of a polycyclic group G, then it is best to specify the set's universe to be PowerGroup(G). If the set's universe is not specified it will be the parent structure of G as returned by Parent(G).