Graphs and groups with unique geodesics

Fuente: arXiv
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Autori principali: Elder, Murray, Gardam, Giles, Piggott, Adam, Spriano, Davide, Townsend, Kane
Natura: Preprint
Pubblicazione: 2023
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author Elder, Murray
Gardam, Giles
Piggott, Adam
Spriano, Davide
Townsend, Kane
author_facet Elder, Murray
Gardam, Giles
Piggott, Adam
Spriano, Davide
Townsend, Kane
contents A connected graph is called \emph{geodetic} if there is a unique geodesic between each pair of vertices. In this paper we prove that if a finitely generated group admits a Cayley graph which is geodetic, then the group must be virtually free. Before now, it was open whether finitely generated and geodetic implied hyperbolic. In fact we prove something more general: if a quasi-transitive locally finite connected undirected graph is geodetic then it is quasi-isometric to a tree. Our main tool is to define a \emph{boundary} of a graph and understand how the local behaviour influences it when the graph is geodetic. Our results unify, and represent significant progress on, research initiated by Ore, Shapiro, and Madlener and Otto.
format Preprint
id arxiv_https___arxiv_org_abs_2311_03730
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Graphs and groups with unique geodesics
Elder, Murray
Gardam, Giles
Piggott, Adam
Spriano, Davide
Townsend, Kane
Group Theory
Combinatorics
05C75, 05C12, 20F65, 20F67, 68Q42
A connected graph is called \emph{geodetic} if there is a unique geodesic between each pair of vertices. In this paper we prove that if a finitely generated group admits a Cayley graph which is geodetic, then the group must be virtually free. Before now, it was open whether finitely generated and geodetic implied hyperbolic. In fact we prove something more general: if a quasi-transitive locally finite connected undirected graph is geodetic then it is quasi-isometric to a tree. Our main tool is to define a \emph{boundary} of a graph and understand how the local behaviour influences it when the graph is geodetic. Our results unify, and represent significant progress on, research initiated by Ore, Shapiro, and Madlener and Otto.
title Graphs and groups with unique geodesics
topic Group Theory
Combinatorics
05C75, 05C12, 20F65, 20F67, 68Q42
url https://arxiv.org/abs/2311.03730