On two-generator subgroups of mapping torus groups

Fuente: arXiv
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Main Authors: Andrew, Naomi, Bering IV, Edgar A., Kapovich, Ilya, Shalen, Peter, Vidussi, Stefano
Format: Preprint
Published: 2024
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author Andrew, Naomi
Bering IV, Edgar A.
Kapovich, Ilya
Shalen, Peter
Vidussi, Stefano
author_facet Andrew, Naomi
Bering IV, Edgar A.
Kapovich, Ilya
Shalen, Peter
Vidussi, Stefano
contents We prove that if $G_ϕ=\langle F, t| t x t^{-1} =ϕ(x), x\in F\rangle$ is the mapping torus group of an injective endomorphism $ϕ: F\to F$ of a free group $F$ (of possibly infinite rank), then every two-generator subgroup $H$ of $G_ϕ$ is either free or a (finitary) sub-mapping torus. As an application we show that if $ϕ\in \mathrm{Out}(F_r)$ (where $r\ge 2$) is a fully irreducible atoroidal automorphism then every two-generator subgroup of $G_ϕ$ is either free or has finite index in $G_ϕ$.
format Preprint
id arxiv_https___arxiv_org_abs_2405_08985
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On two-generator subgroups of mapping torus groups
Andrew, Naomi
Bering IV, Edgar A.
Kapovich, Ilya
Shalen, Peter
Vidussi, Stefano
Group Theory
Primary 20F65, Secondary 20F05, 57M
We prove that if $G_ϕ=\langle F, t| t x t^{-1} =ϕ(x), x\in F\rangle$ is the mapping torus group of an injective endomorphism $ϕ: F\to F$ of a free group $F$ (of possibly infinite rank), then every two-generator subgroup $H$ of $G_ϕ$ is either free or a (finitary) sub-mapping torus. As an application we show that if $ϕ\in \mathrm{Out}(F_r)$ (where $r\ge 2$) is a fully irreducible atoroidal automorphism then every two-generator subgroup of $G_ϕ$ is either free or has finite index in $G_ϕ$.
title On two-generator subgroups of mapping torus groups
topic Group Theory
Primary 20F65, Secondary 20F05, 57M
url https://arxiv.org/abs/2405.08985