English

Finite presentability of twisted Brin-Thompson groups

Group Theory 2024-11-27 v2

Abstract

Given a group GG acting faithfully on a set SS, we characterize precisely when the twisted Brin-Thompson group SVGSV_G is finitely presented. The answer is that SVGSV_G is finitely presented if and only if we have the following: GG is finitely presented, the action of GG on SS has finitely many orbits of two-element subsets of SS, and the stabilizer in GG of any element of SS is finitely generated. Since twisted Brin-Thompson groups are simple, a consequence is that any subgroup of a group admitting an action as above satisfies the Boone-Higman conjecture. In the course of proving this, we also establish a sufficient condition for a group acting cocompactly on a simply connected complex to be finitely presented, even if certain edge stabilizers are not finitely generated, which may be of independent interest.

Keywords

Cite

@article{arxiv.2405.18354,
  title  = {Finite presentability of twisted Brin-Thompson groups},
  author = {Matthew C. B. Zaremsky},
  journal= {arXiv preprint arXiv:2405.18354},
  year   = {2024}
}

Comments

20 pages. V2: Accepted version, to appear in Proc. Roy. Soc. Edinburgh Sect. A

R2 v1 2026-06-28T16:44:21.976Z