Bounding the diameter and eigenvalues of amply regular graphs via Lin-Lu-Yau curvature

Fuente: arXiv
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Main Authors: Huang, Xueping, Liu, Shiping, Xia, Qing
Format: Preprint
Published: 2022
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author Huang, Xueping
Liu, Shiping
Xia, Qing
author_facet Huang, Xueping
Liu, Shiping
Xia, Qing
contents An amply regular graph is a regular graph such that any two adjacent vertices have $α$ common neighbors and any two vertices with distance $2$ have $β$ common neighbors. We prove a sharp lower bound estimate for the Lin--Lu--Yau curvature of any amply regular graph with girth $3$ and $β>α$. The proof involves new ideas relating discrete Ricci curvature with local matching properties: This includes a novel construction of a regular bipartite graph from the local structure and related distance estimates. As a consequence, we obtain sharp diameter and eigenvalue bounds for amply regular graphs.
format Preprint
id arxiv_https___arxiv_org_abs_2210_02988
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Bounding the diameter and eigenvalues of amply regular graphs via Lin-Lu-Yau curvature
Huang, Xueping
Liu, Shiping
Xia, Qing
Combinatorics
Differential Geometry
An amply regular graph is a regular graph such that any two adjacent vertices have $α$ common neighbors and any two vertices with distance $2$ have $β$ common neighbors. We prove a sharp lower bound estimate for the Lin--Lu--Yau curvature of any amply regular graph with girth $3$ and $β>α$. The proof involves new ideas relating discrete Ricci curvature with local matching properties: This includes a novel construction of a regular bipartite graph from the local structure and related distance estimates. As a consequence, we obtain sharp diameter and eigenvalue bounds for amply regular graphs.
title Bounding the diameter and eigenvalues of amply regular graphs via Lin-Lu-Yau curvature
topic Combinatorics
Differential Geometry
url https://arxiv.org/abs/2210.02988