The R$_\infty$ property for pure Artin braid groups

Fuente: arXiv
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Autori principali: Dekimpe, Karel, Gonçalves, Daciberg Lima, Ocampo, Oscar
Natura: Preprint
Pubblicazione: 2020
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author Dekimpe, Karel
Gonçalves, Daciberg Lima
Ocampo, Oscar
author_facet Dekimpe, Karel
Gonçalves, Daciberg Lima
Ocampo, Oscar
contents In this paper we prove that all pure Artin braid groups $P_n$ ($n\geq 3$) have the $R_\infty$ property. In order to obtain this result, we analyse the naturally induced morphism $\operatorname{\text{Aut}}(P_n) \to \operatorname{\text{Aut}}(Γ_2 (P_n)/Γ_3(P_n))$ which turns out to factor through a representation $ρ\colon S_{n+1} \to \operatorname{\text{Aut}}(Γ_2 (P_n)/Γ_3(P_n))$. We can then use representation theory of the symmetric groups to show that any automorphism $α$ of $P_n$ acts on the free abelian group $Γ_2 (P_n)/Γ_3(P_n)$ via a matrix with an eigenvalue equal to 1. This allows us to conclude that the Reidemeister number $R(α)$ of $α$ is $\infty$.
format Preprint
id arxiv_https___arxiv_org_abs_2006_08286
institution arXiv
publishDate 2020
record_format arxiv
spellingShingle The R$_\infty$ property for pure Artin braid groups
Dekimpe, Karel
Gonçalves, Daciberg Lima
Ocampo, Oscar
Group Theory
Representation Theory
Primary: 20E36, Secondary: 20F36, 20E45, 20C30
In this paper we prove that all pure Artin braid groups $P_n$ ($n\geq 3$) have the $R_\infty$ property. In order to obtain this result, we analyse the naturally induced morphism $\operatorname{\text{Aut}}(P_n) \to \operatorname{\text{Aut}}(Γ_2 (P_n)/Γ_3(P_n))$ which turns out to factor through a representation $ρ\colon S_{n+1} \to \operatorname{\text{Aut}}(Γ_2 (P_n)/Γ_3(P_n))$. We can then use representation theory of the symmetric groups to show that any automorphism $α$ of $P_n$ acts on the free abelian group $Γ_2 (P_n)/Γ_3(P_n)$ via a matrix with an eigenvalue equal to 1. This allows us to conclude that the Reidemeister number $R(α)$ of $α$ is $\infty$.
title The R$_\infty$ property for pure Artin braid groups
topic Group Theory
Representation Theory
Primary: 20E36, Secondary: 20F36, 20E45, 20C30
url https://arxiv.org/abs/2006.08286