English

A branch group with unsolvable conjugacy problem

Group Theory 2025-10-21 v2

Abstract

We prove that every finitely generated residually finite group GG can be embedded in a finitely generated branch group Γ\Gamma such that two elements in GG are conjugate in GG if and only if they are conjugate in Γ\Gamma. As an application we construct a finitely generated branch group with solvable word problem and unsolvable conjugacy problem and thereby answer a question of Bartholdi, Grigorchuk, and \v{S}uni\'{k}.

Keywords

Cite

@article{arxiv.2509.12161,
  title  = {A branch group with unsolvable conjugacy problem},
  author = {Alex Bishop and Eduard Schesler},
  journal= {arXiv preprint arXiv:2509.12161},
  year   = {2025}
}
R2 v1 2026-07-01T05:37:20.959Z