On directed and undirected diameters of vertex-transitive graphs

Fuente: arXiv
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Autore principale: Skresanov, Saveliy V.
Natura: Preprint
Pubblicazione: 2023
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author Skresanov, Saveliy V.
author_facet Skresanov, Saveliy V.
contents A directed diameter of a directed graph is the maximum possible distance between a pair of vertices, where paths must respect edge orientations, while undirected diameter is the diameter of the undirected graph obtained by symmetrizing the edges. In 2006 Babai proved that for a connected directed Cayley graph on $n$ vertices the directed diameter is bounded above by a polynomial in undirected diameter and $\log n$. Moreover, Babai conjectured that a similar bound holds for vertex-transitive graphs. We prove this conjecture of Babai, in fact, it follows from a more general bound for connected relations of homogeneous coherent configurations. The main novelty of the proof is a generalization of Ruzsa's triangle inequality from additive combinatorics to the setting of graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2312_12943
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle On directed and undirected diameters of vertex-transitive graphs
Skresanov, Saveliy V.
Combinatorics
05C12 (Primary) 05C20, 20B25 (Secondary)
A directed diameter of a directed graph is the maximum possible distance between a pair of vertices, where paths must respect edge orientations, while undirected diameter is the diameter of the undirected graph obtained by symmetrizing the edges. In 2006 Babai proved that for a connected directed Cayley graph on $n$ vertices the directed diameter is bounded above by a polynomial in undirected diameter and $\log n$. Moreover, Babai conjectured that a similar bound holds for vertex-transitive graphs. We prove this conjecture of Babai, in fact, it follows from a more general bound for connected relations of homogeneous coherent configurations. The main novelty of the proof is a generalization of Ruzsa's triangle inequality from additive combinatorics to the setting of graphs.
title On directed and undirected diameters of vertex-transitive graphs
topic Combinatorics
05C12 (Primary) 05C20, 20B25 (Secondary)
url https://arxiv.org/abs/2312.12943