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JOURNALS // Sibirskie Èlektronnye Matematicheskie Izvestiya [Siberian Electronic Mathematical Reports] // Archive

Sib. Èlektron. Mat. Izv., 2022 Volume 19, Issue 2, Pages 880–888 (Mi semr1547)

This article is cited in 3 papers

Mathematical logic, algebra and number theory

Reidemeister classes in wreath products of abelian groups

M. I. Fraimanab, V. E. Troitskyab

a Dept. of Mech. and Math., Lomonosov Moscow State University, 119991, Moscow, Russia
b Moscow Center for Fundamental and Applied Mathematics, MSU Department

Abstract: Among restricted wreath products $G\wr \mathbb{Z}^k $, where $G$ is a finite abelian group, we find three large classes of groups admitting an automorphism $\varphi$ with finite Reidemeister number $R(\varphi)$ (number of $\varphi$-twisted conjugacy classes). In other words, groups from these classes do not have the $R_\infty$ property.
Moreover, we prove that if $\varphi$ is a finite order automorphism of $G\wr \mathbb{Z}^k$ with $R(\varphi)<\infty$, then $R(\varphi)$ is equal to the number of fixed points of the map $[\rho]\mapsto [\rho\circ \varphi]$ defined on the set of equivalence classes of finite dimensional irreducible unitary representations of $G\wr \mathbb{Z}^k$.

Keywords: Reidemeister number, twisted conjugacy class, Burnside-Frobenius theorem, unitary dual, finite-dimensional representation.

UDC: 512.547.4, 512.544.43

MSC: 20C, 20E45, 22D10

Received July 9, 2022, published November 30, 2022

DOI: 10.33048/semi.2019.16.074



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