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We introduce right eigenvalues and subeigenvalues for square dual complex matrices. An $n \times n$ dual complex Hermitian matrix has exactly $n$ right eigenvalues and subeigenvalues, which are all real. The Hermitian matrix is positive…

Rings and Algebras · Mathematics 2021-11-16 Liqun Qi , Ziyan Luo

Much effort has been spent on characterizing the spectrum of the non-backtracking matrix of certain classes of graphs, with special emphasis on the leading eigenvalue or the second eigenvector. Much less attention has been paid to the…

Combinatorics · Mathematics 2020-07-29 Leo Torres

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…

Combinatorics · Mathematics 2025-12-08 Saieed Akbari , Jonathan Aloni , Maxwell Levit , Bojan Mohar , Steven Xia

For a graph $G$, let $\mathcal{S}(G)$ be the set consisting of Hermitian matrices whose graph is $G$. Denoted by $m_B(G,\lambda)$ the multiplicity of an eigenvalue $\lambda$ of $B(G)\in \mathcal{S}(G)$, we show that $m_B(G,\lambda)\le…

Combinatorics · Mathematics 2023-06-27 Qian-Qian Chen , Ji-Ming Guo , Zhiwen Wang

Graph matrices are a type of matrix which has played a crucial role in analyzing the sum of squares hierarchy on average case problems. However, except for rough norm bounds, little is known about graph matrices. In this paper, we take a…

Combinatorics · Mathematics 2024-06-26 Wenjun Cai , Aaron Potechin

An important facet of the inverse eigenvalue problem for graphs is to determine the minimum number of distinct eigenvalues of a particular graph. We resolve this question for the join of a connected graph with a path. We then focus on…

We develop eigenvalue estimates for the Laplacians on discrete and metric graphs using different types of boundary conditions at the vertices of the metric graph. Via an explicit correspondence of the equilateral metric and discrete graph…

Spectral Theory · Mathematics 2008-04-08 Olaf Post , Fernando Lledo

In this paper we study the complementarity spectrum of digraphs, with special attention to the problem of digraph characterization through this complementarity spectrum. That is, whether two non-isomorphic digraphs with the same number of…

Combinatorics · Mathematics 2021-10-11 Diego Bravo , Florencia Cubría , Marcelo Fiori , Vilmar Trevisan

The goal of this article is to study how much the eigenvalues of large Hermitian random matrices deviate from certain deterministic locations -- or in other words, to investigate optimal rigidity estimates for the eigenvalues. We do this in…

Probability · Mathematics 2019-06-05 Tom Claeys , Benjamin Fahs , Gaultier Lambert , Christian Webb

We introduce a hypergraph matrix, named the unified matrix, and use it to represent the hypergraph as a graph. We show that the unified matrix of a hypergraph is identical to the adjacency matrix of the associated graph. This enables us to…

Combinatorics · Mathematics 2024-11-12 R. Vishnupriya , R. Rajkumar

We give an overview of different approaches to measuring the similarity of, or the distance between, two graphs, highlighting connections between these approaches. We also discuss the complexity of computing the distances.

Discrete Mathematics · Computer Science 2025-03-19 Martin Grohe

One of the aims of this paper is to solve an open problem of Lovasz about relations between graph spectra and cut-distance. The paper starts with several inequalities between two versions of the cut-norm and the two largest singular values…

Functional Analysis · Mathematics 2009-12-03 Vladimir Nikiforov

Graph representation matrices are essential tools in graph data analysis. Recently, Hermitian adjacency matrices have been proposed to investigate directed graph structures. Previous studies have demonstrated that these matrices can extract…

Combinatorics · Mathematics 2025-07-21 Keishi Sando , Hideitsu Hino

We improve recent results relating graph eigenvalues to other graph parameters like girth, domination number, and minimum degree.

Combinatorics · Mathematics 2007-05-23 Vladimir Nikiforov

The eccentricity matrix of a connected graph $G$ is obtained from the distance matrix of $G$ by retaining the largest distances in each row and each column, and setting the remaining entries as $0$. In this article, a conjecture about the…

Combinatorics · Mathematics 2020-08-18 Iswar Mahato , R. Gurusamy , M. Rajesh Kannan , S. Arockiaraj

We generalize classical results in spectral graph theory and linear algebra more broadly, from the case where the underlying matrix is Hermitian to the case where it is non-Hermitian. New admissibility conditions are introduced to replace…

Spectral Theory · Mathematics 2019-05-21 Edinah K. Gnang , James M. Murphy

In this paper, we give estimates for both upper and lower bounds of eigenvalues of a simple matrix. The estimates are shaper than the known results.

Numerical Analysis · Mathematics 2014-04-15 J. Chen

We review our recent results on pseudo-hermitian random matrix theory which were hitherto presented in various conferences and talks. (Detailed accounts of our work will appear soon in separate publications.) Following an introduction of…

Mathematical Physics · Physics 2021-10-27 Joshua Feinberg , Roman Riser

In this paper, we introduce a matrix for a mixed graph, called the integrated adjacency matrix. This matrix uniquely determines a mixed graph, as long as the indices of the matrix are specified. Additionally, we associate an (undirected)…

Combinatorics · Mathematics 2025-11-27 G. Kalaivani , R. Rajkumar

We prove new explicit asymptotic formulae between (geometric) eigenvalues in max-algebra and classical distinguished eigenvalues of nonnegative matrices, which are useful tools for transferring results between both settings. We establish…

Functional Analysis · Mathematics 2021-11-09 S. M. Manjegani , A. Peperko , H. Shokooh Saljooghi