Monatshefte für Mathematik ( IF 0.9 ) Pub Date : 2021-02-10 , DOI: 10.1007/s00605-020-01484-7 Karel Dekimpe , Daciberg Lima Gonçalves , Oscar Ocampo
In this paper we prove that all pure Artin braid groups \(P_n\) (\(n\ge 3\)) have the \(R_\infty \) property. In order to obtain this result, we analyse the naturally induced morphism \({\text {Aut}}\left( {P_n}\right) \longrightarrow {\text {Aut}}\left( {\Gamma _2 (P_n)/\Gamma _3(P_n)}\right) \) which turns out to factor through a representation \(\rho :S_{{n+1}} \longrightarrow {\text {Aut}}\left( {\Gamma _2 (P_n)/\Gamma _3(P_n)}\right) \). We can then use representation theory of the symmetric groups to show that any automorphism \(\alpha \) of \(P_n\) acts on the free abelian group \(\Gamma _2 (P_n)/\Gamma _3(P_n)\) via a matrix with an eigenvalue equal to 1. This allows us to conclude that the Reidemeister number \(R(\alpha )\) of \(\alpha \) is \(\infty \).
中文翻译:
纯Artin编织群的$$ R_ \ infty $$ R∞属性
在本文中,我们证明所有纯Artin编织组\(P_n \)(\(n \ ge 3 \))具有\(R_ \ infty \)属性。为了获得此结果,我们分析自然诱发的态射\\ {{text {Aut}} \ left({P_n} \ right)\ longrightarrow {\ text {Aut}} \ left({\ Gamma _2(P_n) / \ Gamma _3(P_n)} \ right)\)会通过表示形式\(\ rho:S _ {{n + 1}} \ longrightarrow {\ text {Aut}} \ left({\ Gamma _2 (P_n)/ \ Gamma _3(P_n)} \ right)\)。然后,我们可以使用对称组的表示理论来证明\(P_n \)的任何自同构\(\ alpha \)都作用于自由阿贝尔群\(\ Gamma _2(P_n)/ \ Gamma _3(P_n)\)经由与本征值等于1。这使我们得出结论一个矩阵,该数Reidemeister \(R(\阿尔法)\)的\(\阿尔法\)是\(\ infty \) 。