Generalizing the Hilton–Mislin genus group

Abstract

For any group H, let H be the set of all isomorphism classes of groups K such that K H . For a finitely generated group H having finite commu- Ž .tator subgroup H, H , we define a group structure on H in terms of embed- dings of K into H, for groups K of which the isomorphism classes belong to Ž . H . If H is nilpotent, then the group we obtain coincides with the genus group Ž .GG H defined by Hilton and Mislin. We obtain some new results on Hilton Mislin genus groups as well as generalizations of known results.