Locally chordal graphs

Fuente: arXiv
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Main Authors: Abrishami, Tara, Knappe, Paul, Kobler, Jonas
Format: Preprint
Published: 2025
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author Abrishami, Tara
Knappe, Paul
Kobler, Jonas
author_facet Abrishami, Tara
Knappe, Paul
Kobler, Jonas
contents In this paper we study locally chordal graphs, i.e. graphs where every small-radius ball is chordal. We prove four characterizations of locally chordal graphs. Two are counterparts of the classic descriptions of chordal graphs via induced subgraphs and via minimal separators. For the latter, we rely on the local separators introduced in [CJKK25]. Another characterization is via the local covering, which was introduced in [DJKK22] to study local-global characteristics of graphs using coverings from topology. Our final characterization of locally chordal graphs is in terms of their binary cycle spaces. This gives a new characterization of chordal graphs as wheel-free graphs whose binary cycle space is generated by triangles. Together, these results demonstrate the potential of local-global tools to uncover rich new properties. Our results in this paper also form the basis of our local-global analysis of locally chordal graphs [AKb], where we develop a local-global perspective into structural characterizations.
format Preprint
id arxiv_https___arxiv_org_abs_2501_17320
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Locally chordal graphs
Abrishami, Tara
Knappe, Paul
Kobler, Jonas
Combinatorics
05C83, 05C69, 05C40, 05C38
In this paper we study locally chordal graphs, i.e. graphs where every small-radius ball is chordal. We prove four characterizations of locally chordal graphs. Two are counterparts of the classic descriptions of chordal graphs via induced subgraphs and via minimal separators. For the latter, we rely on the local separators introduced in [CJKK25]. Another characterization is via the local covering, which was introduced in [DJKK22] to study local-global characteristics of graphs using coverings from topology. Our final characterization of locally chordal graphs is in terms of their binary cycle spaces. This gives a new characterization of chordal graphs as wheel-free graphs whose binary cycle space is generated by triangles. Together, these results demonstrate the potential of local-global tools to uncover rich new properties. Our results in this paper also form the basis of our local-global analysis of locally chordal graphs [AKb], where we develop a local-global perspective into structural characterizations.
title Locally chordal graphs
topic Combinatorics
05C83, 05C69, 05C40, 05C38
url https://arxiv.org/abs/2501.17320