3 papers
math.CO2026
Orthogonal signed graphs of degree 5
Maxwell Levit, Bojan Mohar, Behruz Tayfeh-Rezaie
An orthogonal signed graph is a connected signed graph whose signed adjacency matrix has pairwise orthogonal rows. They are closely related to Hadamard matrices, maximal arrangemen…
math.CO2025
Spectrally symmetric orientations of graphs
Saieed Akbari, Jonathan Aloni, Maxwell Levit +2
The Hermitian adjacency matrices of digraphs based on the sixth root of unity were introduced in [B. Mohar, A new kind of Hermitian matrices for digraphs, Linear Alg. Appl. (2020)]…
math.CO2025
Hermitian adjacency matrices with at most three distinct eigenvalues
Saieed Akbari, Jonathan Aloni, Maxwell Levit +2
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 ei…