On acylindrical tree actions and outer automorphism group of Baumslag-Solitar groups

Fuente: arXiv
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Autori principali: Som, Bratati, Wang, Daxun
Natura: Preprint
Pubblicazione: 2025
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author Som, Bratati
Wang, Daxun
author_facet Som, Bratati
Wang, Daxun
contents This paper explores acylindrical actions on trees, building on previous works related to the mapping class group and projection complexes. We demonstrate that the quotient action of a $1$-acylindrical action of a group on a tree by an equivariant family of subgroups remains $1$-acylindrical. We establish criteria for ensuring that this quotient action is non-elementary acylindrical, thus preserving acylindrical hyperbolicity of the group. Additionally, we show that the fundamental group of a graph of groups admits the largest acylindrical action on its Bass-Serre tree under certain conditions. As an application, we analyze the outer automorphism group of non-solvable Baumslag-Solitar groups, we prove its acylindrical hyperbolicity, highlighting the differences between various tree actions and identifying the largest acylindrical action.
format Preprint
id arxiv_https___arxiv_org_abs_2501_01754
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On acylindrical tree actions and outer automorphism group of Baumslag-Solitar groups
Som, Bratati
Wang, Daxun
Group Theory
Geometric Topology
20E08, 20F28, 20F65
This paper explores acylindrical actions on trees, building on previous works related to the mapping class group and projection complexes. We demonstrate that the quotient action of a $1$-acylindrical action of a group on a tree by an equivariant family of subgroups remains $1$-acylindrical. We establish criteria for ensuring that this quotient action is non-elementary acylindrical, thus preserving acylindrical hyperbolicity of the group. Additionally, we show that the fundamental group of a graph of groups admits the largest acylindrical action on its Bass-Serre tree under certain conditions. As an application, we analyze the outer automorphism group of non-solvable Baumslag-Solitar groups, we prove its acylindrical hyperbolicity, highlighting the differences between various tree actions and identifying the largest acylindrical action.
title On acylindrical tree actions and outer automorphism group of Baumslag-Solitar groups
topic Group Theory
Geometric Topology
20E08, 20F28, 20F65
url https://arxiv.org/abs/2501.01754