{ "id": "2207.04294", "version": "v1", "published": "2022-07-09T16:17:10.000Z", "updated": "2022-07-09T16:17:10.000Z", "title": "Reidemeister classes in some wreath products by $\\mathbb Z^k$", "authors": [ "Mikhail I. Fraiman", "Evgenij V. Troitsky" ], "categories": [ "math.GR", "math.DS", "math.RT" ], "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. If a general automorphism $\\varphi$ of $G\\wr \\mathbb Z^k$ has a finite order (this is the case for $\\varphi$ detected in the first part of the paper) and $R(\\varphi)<\\infty$, we prove that $R(\\varphi)$ coincides with the number of equivalence classes of finite-dimensional irreducible unitary representations of $G\\wr \\mathbb Z^k$, which are fixed by the dual map $[\\rho]\\mapsto [\\rho\\circ \\varphi]$ (i.e. we prove the conjecture about finite twisted Burnside-Frobenius theorem, TBFT$_f$, for these $\\varphi$).", "revisions": [ { "version": "v1", "updated": "2022-07-09T16:17:10.000Z" } ], "analyses": { "subjects": [ "20E45", "22D10", "37C25" ], "keywords": [ "reidemeister classes", "finite twisted burnside-frobenius theorem", "finite reidemeister number", "finite-dimensional irreducible unitary representations", "finite abelian group" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }