Virtual retractions in free constructions

Fuente: arXiv
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Autori principali: Urigüen, Jon Merladet, Minasyan, Ashot
Natura: Preprint
Pubblicazione: 2025
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author Urigüen, Jon Merladet
Minasyan, Ashot
author_facet Urigüen, Jon Merladet
Minasyan, Ashot
contents A group $G$ has property (VRC) if every cyclic subgroup is a virtual retract. This property is stable under many standard group-theoretic constructions and is enjoyed by all virtually special groups (in the sense of Haglund and Wise). In this paper we study property (VRC) for fundamental groups of finite graphs of groups. Our main criterion shows that the fundamental group of a finite graph of finitely generated virtually abelian groups has (VRC) if and only if it has a homomorphism to a Euclidean-by-finite group that is injective on all vertex groups. This result allows us to determine property (VRC) for such groups using basic tools from Euclidean Geometry and Linear Algebra. We use it to produce examples and to give sufficient criteria for fundamental groups of finite graphs of finitely generated abelian groups with cyclic edge groups to have (VRC). In the last two sections and in the appendix we give applications of property (VRC). We show that if a fundamental group of a finite graph of groups with finitely generated virtually abelian vertex groups has (VRC) then it is CAT($0$). We also show that tubular groups with (VRC) are virtually free-by-cyclic and virtually special.
format Preprint
id arxiv_https___arxiv_org_abs_2505_18054
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Virtual retractions in free constructions
Urigüen, Jon Merladet
Minasyan, Ashot
Group Theory
20E06, 20E26, 20F65
A group $G$ has property (VRC) if every cyclic subgroup is a virtual retract. This property is stable under many standard group-theoretic constructions and is enjoyed by all virtually special groups (in the sense of Haglund and Wise). In this paper we study property (VRC) for fundamental groups of finite graphs of groups. Our main criterion shows that the fundamental group of a finite graph of finitely generated virtually abelian groups has (VRC) if and only if it has a homomorphism to a Euclidean-by-finite group that is injective on all vertex groups. This result allows us to determine property (VRC) for such groups using basic tools from Euclidean Geometry and Linear Algebra. We use it to produce examples and to give sufficient criteria for fundamental groups of finite graphs of finitely generated abelian groups with cyclic edge groups to have (VRC). In the last two sections and in the appendix we give applications of property (VRC). We show that if a fundamental group of a finite graph of groups with finitely generated virtually abelian vertex groups has (VRC) then it is CAT($0$). We also show that tubular groups with (VRC) are virtually free-by-cyclic and virtually special.
title Virtual retractions in free constructions
topic Group Theory
20E06, 20E26, 20F65
url https://arxiv.org/abs/2505.18054