Minimum number of distinct eigenvalues of distance-regular and signed Johnson graphs

Fuente: arXiv
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Main Authors: Fallat, Shaun, Gupta, Himanshu, Herman, Allen, Parenteau, Johnna
Format: Preprint
Published: 2024
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author Fallat, Shaun
Gupta, Himanshu
Herman, Allen
Parenteau, Johnna
author_facet Fallat, Shaun
Gupta, Himanshu
Herman, Allen
Parenteau, Johnna
contents We study the minimum number of distinct eigenvalues over a collection of matrices associated with a graph. Lower bounds are derived based on the existence or non-existence of certain cycle(s) in a graph. A key result proves that every Johnson graph has a signed variant with exactly two distinct eigenvalues. We also explore applications to weighing matrices, linear ternary codes, tight frames, and compute the minimum rank of Johnson graphs. Further results involve the minimum number of distinct eigenvalues for graphs in association schemes, distance-regular graphs, and Hamming graphs. We also draw some connections with simplicial complexes and higher-order Laplacians.
format Preprint
id arxiv_https___arxiv_org_abs_2411_00250
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Minimum number of distinct eigenvalues of distance-regular and signed Johnson graphs
Fallat, Shaun
Gupta, Himanshu
Herman, Allen
Parenteau, Johnna
Combinatorics
Primary 05C50, 05E30, Secondary 05C22, 15A18
We study the minimum number of distinct eigenvalues over a collection of matrices associated with a graph. Lower bounds are derived based on the existence or non-existence of certain cycle(s) in a graph. A key result proves that every Johnson graph has a signed variant with exactly two distinct eigenvalues. We also explore applications to weighing matrices, linear ternary codes, tight frames, and compute the minimum rank of Johnson graphs. Further results involve the minimum number of distinct eigenvalues for graphs in association schemes, distance-regular graphs, and Hamming graphs. We also draw some connections with simplicial complexes and higher-order Laplacians.
title Minimum number of distinct eigenvalues of distance-regular and signed Johnson graphs
topic Combinatorics
Primary 05C50, 05E30, Secondary 05C22, 15A18
url https://arxiv.org/abs/2411.00250