Property (VRC) and virtual fibering for amalgamated free products

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Hauptverfasser: Urigüen, Jon Merladet, Minasyan, Ashot
Format: Preprint
Veröffentlicht: 2025
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author Urigüen, Jon Merladet
Minasyan, Ashot
author_facet Urigüen, Jon Merladet
Minasyan, Ashot
contents This paper focuses on studying properties of amalgamated free products $G=G_1*_{G_0} G_2$, where the amalgamated subgroup $G_0$ is virtually cyclic. First, we prove that if the factors $G_1$ and $G_2$ are finitely generated virtually abelian groups then $G$ can be mapped to another virtually abelian group so that this homomorphism is injective on each factor. We then present several applications of this result. In particular, we show that if $G_1$ and $G_2$ have property (VRC) (that is, every cyclic subgroup is a virtual retract), then the same is true for $G$. We also prove that $G$ inherits some residual properties (such as residual finiteness or virtual residual solvability) from the factors $G_i$, provided $G_0$ is a virtual retract of $G_i$, for $i=1,2$. Finally, we give necessary and sufficient conditions for $G$ to be (virtually) $F_m$-fibered. In particular, we fully characterize when an amalgamated product of two (finitely generated free)-by-cyclic groups over a cyclic subgroup is free-by-cyclic or virtually free-by-cyclic.
format Preprint
id arxiv_https___arxiv_org_abs_2511_21293
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Property (VRC) and virtual fibering for amalgamated free products
Urigüen, Jon Merladet
Minasyan, Ashot
Group Theory
20E06, 20E08, 20E26, 20F65
This paper focuses on studying properties of amalgamated free products $G=G_1*_{G_0} G_2$, where the amalgamated subgroup $G_0$ is virtually cyclic. First, we prove that if the factors $G_1$ and $G_2$ are finitely generated virtually abelian groups then $G$ can be mapped to another virtually abelian group so that this homomorphism is injective on each factor. We then present several applications of this result. In particular, we show that if $G_1$ and $G_2$ have property (VRC) (that is, every cyclic subgroup is a virtual retract), then the same is true for $G$. We also prove that $G$ inherits some residual properties (such as residual finiteness or virtual residual solvability) from the factors $G_i$, provided $G_0$ is a virtual retract of $G_i$, for $i=1,2$. Finally, we give necessary and sufficient conditions for $G$ to be (virtually) $F_m$-fibered. In particular, we fully characterize when an amalgamated product of two (finitely generated free)-by-cyclic groups over a cyclic subgroup is free-by-cyclic or virtually free-by-cyclic.
title Property (VRC) and virtual fibering for amalgamated free products
topic Group Theory
20E06, 20E08, 20E26, 20F65
url https://arxiv.org/abs/2511.21293