English

$\mathcal{C}$-Hereditarily conjugacy separable groups and wreath products

Group Theory 2026-01-01 v2

Abstract

We provide a necessary and sufficient condition for the restricted wreath product ABA\wr B to be C\mathcal{C}-hereditarily conjugacy separable where C\mathcal{C} is an extension-closed pseudovariety of finite groups. Moreover, we prove that the Grigorchuk group is 2-hereditarily conjugacy separable. As an application, we demonstrate that the lamplighter groups and ZZ\mathbb{Z} \wr \mathbb{Z} are hereditarily conjugacy separable (but not pp-conjugacy separable for any prime pp) which provides infinitely many new examples of solvable, non-polycyclic hereditarily conjugacy separable groups. Furthermore, we study wreath products of cyclic subgroup separable groups and the derived length of iterated wreath products of solvable groups with an abelian base group and, as an application, we give an explicit construction of non-polycyclic hereditarily conjugacy separable groups of arbitrary derived length as an iterated wreath products of abelian groups.

Keywords

Cite

@article{arxiv.2409.06200,
  title  = {$\mathcal{C}$-Hereditarily conjugacy separable groups and wreath products},
  author = {Alexander Bishop and Michal Ferov and Mark Pengitore},
  journal= {arXiv preprint arXiv:2409.06200},
  year   = {2026}
}

Comments

Second version, along with minor edits following referees' comments, the manuscript now includes two more sections: Section 6 shows that the class of cyclic subgroup separable groups is closed under forming wreath products and Section 7 gives an explicit construction of non-polycyclic solvable hereditarily conjugacy separable groups of arbitrary derived length. Comments and suggestions welcome!

R2 v1 2026-06-28T18:39:26.211Z