Finite ๐C-groups
Abstract
Let G be a group and DS(G)={Hโฒ|HโคG}. G is said to be a ๐C-group if DS(G) is a chain under set inclusion. In this paper, we prove that a finite ๐C-group is a semidirect product of a Sylow p-subgroup and an abelian pโฒ-subgroup. For the case of G being a finite p-group, we obtain an optimal upper bound of d(Gโฒ) for a ๐Cp-group G. We also prove that a ๐Cp-group is metabelian when pโค3 and provide an example showing that a non-abelian ๐Cp-group is not necessarily metabelian when pโฅ5. In particular, ๐C 2-groups are characterized.
Communicated by M. L. Lewis