English

Reidemeister classes in some wreath products by $\mathbb Z^k$

Group Theory 2023-05-23 v1 Dynamical Systems Representation Theory

Abstract

Among restricted wreath products GZkG\wr \mathbb Z^k , where GG is a finite Abelian group, we find three large classes of groups admitting an automorphism φ\varphi with finite Reidemeister number R(φ)R(\varphi) (number of φ\varphi-twisted conjugacy classes). In other words, groups from these classes do not have the RR_\infty property. If a general automorphism φ\varphi of GZkG\wr \mathbb Z^k has a finite order (this is the case for φ\varphi detected in the first part of the paper) and R(φ)<R(\varphi)<\infty, we prove that R(φ)R(\varphi) coincides with the number of equivalence classes of finite-dimensional irreducible unitary representations of GZkG\wr \mathbb Z^k, which are fixed by the dual map [ρ][ρφ][\rho]\mapsto [\rho\circ \varphi] (i.e. we prove the conjecture about finite twisted Burnside-Frobenius theorem, TBFTf_f, for these φ\varphi).

Keywords

Cite

@article{arxiv.2207.04294,
  title  = {Reidemeister classes in some wreath products by $\mathbb Z^k$},
  author = {Mikhail I. Fraiman and Evgenij V. Troitsky},
  journal= {arXiv preprint arXiv:2207.04294},
  year   = {2023}
}