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Related papers: Hermitian adjacency matrices of mixed multigraphs

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We present the algebraic representation and basic algorithms for MultiAspect Graphs (MAGs). A MAG is a structure capable of representing multilayer and time-varying networks, as well as higher-order networks, while also having the property…

Discrete Mathematics · Computer Science 2016-09-27 Klaus Wehmuth , Éric Fleury , Artur Ziviani

Directed mixed graphs permit directed and bidirected edges between any two vertices. They were first considered in the path analysis developed by Sewall Wright and play an essential role in statistical modeling. We introduce a matrix…

Statistics Theory · Mathematics 2024-07-23 Qingyuan Zhao

This work considers the distributed computation of the one-to-one vertex correspondences between two undirected and connected graphs, which is called \textit{graph matching}, over multi-agent networks. Given two \textit{isomorphic} and…

Optimization and Control · Mathematics 2020-02-21 Quoc Van Tran , Zhiyong Sun , Brian D. O. Anderson , Hyo-Sung Ahn

Sparse non-Hermitian random matrices arise in the study of disordered physical systems with asymmetric local interactions, and have applications ranging from neural networks to ecosystem dynamics. The spectral characteristics of these…

Statistical Mechanics · Physics 2024-02-21 Fernando Lucas Metz , Izaak Neri , Tim Rogers

The use of complex networks as a modern approach to understanding the world and its dynamics is well-established in literature. The adjacency matrix, which provides a one-to-one representation of a complex network, can also yield several…

Social and Information Networks · Computer Science 2023-01-23 Mariane B. Neiva , Odemir M. Bruno

Local operations of combinatorial structures (graphs, Hadamard matrices, codes, designs) that maintain the basic parameters unaltered, have been widely used in the literature under the name of switching. We show an equivalence between two…

Combinatorics · Mathematics 2024-10-15 Aida Abiad , Louka Peters

In this article we are introducing combinatorial spectra of graphs, this is a generalization of $H$-Hamiltonian spectra. The main motivation was to made from $H$-Hamiltonian spectra an operation and develop some algebra in this field. An…

Combinatorics · Mathematics 2023-11-21 Martin Dzúrik

Two graphs $G$ and $H$ are \emph{cospectral} if the adjacency matrices share the same spectrum. Constructing cospectral non-isomorphic graphs has been studied extensively for many years and various constructions are known in the literature,…

Combinatorics · Mathematics 2024-09-17 Lihuan Mao , Fu Yan

Since the introduction of the Hermitian adjacency matrix for digraphs, interest in so-called complex unit gain graphs has surged. In this work, we consider gain graphs whose spectra contain the minimum number of two distinct eigenvalues.…

Combinatorics · Mathematics 2021-05-20 Pepijn Wissing , Edwin R. van Dam

A mixed extension of a graph $G$ is a graph $H$ obtained from $G$ by replacing each vertex of $G$ by a clique or a coclique, whilst two vertices in $H$ corresponding to distinct vertices $x$ and $y$ of $G$ are adjacent whenever $x$ and $y$…

Combinatorics · Mathematics 2019-07-23 Willem H. Haemers , Sezer Sorgun , Hatice Topcu

Spectral hypergraph theory mainly concerns using hypergraph spectra to obtain structural information about the given hypergraphs. The study of cospectral hypergraphs is important since it reveals which hypergraph properties cannot be…

Combinatorics · Mathematics 2024-06-14 Aida Abiad , Antonina P. Khramova

Let $\Gamma=(G,\sigma)$ be a signed graph, where $\sigma$ is the sign function on the edges of $G$. In this paper, we use the operation of partial transpose to obtain non-isomorphic Laplacian cospectral signed graphs. We will introduce two…

Combinatorics · Mathematics 2022-05-19 Tahir Shamsher , S. Pirzada , Mushtaq A. Bhat

A lower bound on the chromatic number of a graph is derived by majorization of spectra of weighted adjacency matrices. These matrices are given by Hadamard products of the adjacency matrix and arbitrary Hermitian matrices.

Discrete Mathematics · Computer Science 2007-05-23 Pawel Wocjan , Dominik Janzing , Thomas Beth

We consider Hoffman's program about the limit points of the spectral radius of the Hermitian adjacency matrix of mixed graphs. In particular, we determine all mixed graphs without negative $4$-cycle whose spectral radius does not exceed…

Combinatorics · Mathematics 2025-08-06 Yuantian Yu , Edwin R. van Dam

A mixed graph is said to be \textit{integral} if all the eigenvalues of its Hermitian adjacency matrix are integer. The \textit{mixed circulant graph} $Circ(\mathbb{Z}_n,\mathcal{C})$ is a mixed graph on the vertex set $\mathbb{Z}_n$ and…

Combinatorics · Mathematics 2022-06-23 Monu Kadyan , Bikash Bhattacharjya

Here, the structural symmetries of a hypergraph are represented through equivalence relations on the vertex set of the hypergraph. A matrix associated with the hypergraph may not reflect a specific structural symmetry. In the context of a…

Combinatorics · Mathematics 2025-08-12 Anirban Banerjee , Samiron Parui

The chordal ring (CR) graphs are a well-known family of graphs used to model some interconnection networks for computer systems in which all nodes are in a cycle. Generalizing the CR graphs, in this paper, we introduce the families of…

Combinatorics · Mathematics 2024-09-04 M. A. Reyes , C. Dalfó , M. A. Fiol

In this paper we will apply the tensor and its traces to investigate the spectral characterization of unicyclic graphs. Let $G$ be a graph and $G^m$ be the $m$-th power (hypergraph) of $G$. The spectrum of $G$ is referring to its adjacency…

Combinatorics · Mathematics 2025-07-22 Yi-Zheng Fan , Hong-Xia Yang , Jian Zheng

In the theory of line graphs of undirected graphs there exists an important theorem linking the incidence matrix of the root graph to the adjacency matrix of its line graph. For directed or mixed graphs, however, the exists no analogous…

Combinatorics · Mathematics 2022-05-12 Mohammad Abudayah , Omar Alomari , Torsten Sander

For a given hypergraph, an orientation can be assigned to the vertex-edge incidences. This orientation is used to define the adjacency and Laplacian matrices. In addition to studying these matrices, several related structures are…

Combinatorics · Mathematics 2015-09-08 Nathan Reff