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Hauptverfasser: Coulon, Rémi, Hilion, Arnaud, Horbez, Camille, Levitt, Gilbert
Format: Preprint
Veröffentlicht: 2025
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Online-Zugang:https://arxiv.org/abs/2512.05569
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author Coulon, Rémi
Hilion, Arnaud
Horbez, Camille
Levitt, Gilbert
author_facet Coulon, Rémi
Hilion, Arnaud
Horbez, Camille
Levitt, Gilbert
contents Let $G$ be a toral relatively hyperbolic group, and let $φ\in\mathrm{Aut}(G)$. We prove that, under iteration of $φ$, the conjugacy length $||φ^n(g)||$ of every element $g\in G$ grows like $n^dλ^n$ for some $d\in\mathbb{N}$ and some algebraic integer $λ\geq 1$. For a given $φ$, only finitely many values of $d$ and $λ$ occur as $g$ varies in $G$. The same statements hold for the growth of the word length $|φ^n(g)|$. For $G$ hyperbolic, we generalize polynomial subgroups: we show that, for a given growth type $n^dλ^n$ other than $1$, there is a malnormal family of quasiconvex subgroups $K_1,\dots,K_p$ such that a conjugacy class $[g]$ grows at most like $n^dλ^n$ if and only if $g$ is conjugate into one of the subgroups $K_i$.
format Preprint
id arxiv_https___arxiv_org_abs_2512_05569
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle PolExp growth for automorphisms of toral relatively hyperbolic groups
Coulon, Rémi
Hilion, Arnaud
Horbez, Camille
Levitt, Gilbert
Group Theory
Let $G$ be a toral relatively hyperbolic group, and let $φ\in\mathrm{Aut}(G)$. We prove that, under iteration of $φ$, the conjugacy length $||φ^n(g)||$ of every element $g\in G$ grows like $n^dλ^n$ for some $d\in\mathbb{N}$ and some algebraic integer $λ\geq 1$. For a given $φ$, only finitely many values of $d$ and $λ$ occur as $g$ varies in $G$. The same statements hold for the growth of the word length $|φ^n(g)|$. For $G$ hyperbolic, we generalize polynomial subgroups: we show that, for a given growth type $n^dλ^n$ other than $1$, there is a malnormal family of quasiconvex subgroups $K_1,\dots,K_p$ such that a conjugacy class $[g]$ grows at most like $n^dλ^n$ if and only if $g$ is conjugate into one of the subgroups $K_i$.
title PolExp growth for automorphisms of toral relatively hyperbolic groups
topic Group Theory
url https://arxiv.org/abs/2512.05569