Hermitian adjacency matrices with at most three distinct eigenvalues

Fuente: arXiv
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Autores principales: Akbari, Saieed, Aloni, Jonathan, Levit, Maxwell, Mohar, Bojan, Xia, Steven
Formato: Preprint
Publicado: 2025
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author Akbari, Saieed
Aloni, Jonathan
Levit, Maxwell
Mohar, Bojan
Xia, Steven
author_facet Akbari, Saieed
Aloni, Jonathan
Levit, Maxwell
Mohar, Bojan
Xia, Steven
contents We study oriented graphs whose Hermitian adjacency matrices of the second kind have few eigenvalues. We give a complete characterization of the oriented graphs with two distinct eigenvalues, showing that there are only four such graphs. We extend this result to mixed graphs. We show that there are infinitely many regular tournaments with three distinct eigenvalues. We extend our main results to Hermitian adjacency matrices defined over other roots of unity.
format Preprint
id arxiv_https___arxiv_org_abs_2503_13781
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Hermitian adjacency matrices with at most three distinct eigenvalues
Akbari, Saieed
Aloni, Jonathan
Levit, Maxwell
Mohar, Bojan
Xia, Steven
Combinatorics
We study oriented graphs whose Hermitian adjacency matrices of the second kind have few eigenvalues. We give a complete characterization of the oriented graphs with two distinct eigenvalues, showing that there are only four such graphs. We extend this result to mixed graphs. We show that there are infinitely many regular tournaments with three distinct eigenvalues. We extend our main results to Hermitian adjacency matrices defined over other roots of unity.
title Hermitian adjacency matrices with at most three distinct eigenvalues
topic Combinatorics
url https://arxiv.org/abs/2503.13781