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Switching is an operation on a graph that does not change the spectrum of the adjacency matrix, thus producing cospectral graphs. An important activity in the field of spectral graph theory is the characterization of graphs by their…

Combinatorics · Mathematics 2025-10-03 Aida Abiad , Nils Van de Berg , Robin Simoens

We investigate when a complete graph $K_n$ with some edges deleted is determined by its adjacency spectrum. It is shown to be the case if the deleted edges form a matching, a complete graph $K_m$ provided $m \leq n-2$, or a complete…

Combinatorics · Mathematics 2012-11-27 Marc Cámara , Willem H. Haemers

We construct infinite families of graphs that are determined by their generalized spectrum. This construction is based on new formulae for the determinant of the walk matrix of a graph. The graphs constructed here all satisfy a lower…

Combinatorics · Mathematics 2018-09-05 Fenjin Liu , Johannes Siemons , Wei Wang

Given a graph $G$ on $n$ vertices, its adjacency matrix and degree diagonal matrix are represented by $A(G)$ and $D(G)$, respectively. The $Q$-spectrum of $G$ consists of all the eigenvalues of its signless Laplacian matrix $Q(G)=A(G)+D(G)$…

Combinatorics · Mathematics 2023-07-28 Gui-Xian Tian , Jun-Xing Wu , Shu-Yu Cui , Hui-Lu Sun

In this paper we consider the concept of preintersection numbers of a graph. These numbers are determined by the spectrum of the adjacency matrix of the graph, and generalize the intersection numbers of a distance-regular graph. By using…

Combinatorics · Mathematics 2016-04-20 A. Abiad , E. R. van Dam , M. A. Fiol

We consider a hierarchy of graph invariants that naturally extends the spectral invariants defined by F\"urer (Lin. Alg. Appl. 2010) based on the angles formed by the set of standard basis vectors and their projections onto eigenspaces of…

Computational Complexity · Computer Science 2025-05-06 V. Arvind , Frank Fuhlbrück , Johannes Köbler , Oleg Verbitsky

Sufficient conditions for a simple graph to be characterized up to isomorphism given its spectrum and the spectrum of its complement graph are known due to Wang and Xu. This note establishes a related sufficient condition in the presence of…

Combinatorics · Mathematics 2026-02-25 Alexander Van Werde

Matrix-based centrality measures have enjoyed significant popularity in network analysis, in no small part due to our ability to rigorously analyze their behavior as parameters vary. Recent work has considered the relationship between…

Social and Information Networks · Computer Science 2019-02-06 Eric Horton , Kyle Kloster , Blair D. Sullivan

In the past decades, graphs that are determined by their spectrum have received more attention, since they have been applied to several fields, such as randomized algorithms, combinatorial optimization problems and machine learning. An…

Combinatorics · Mathematics 2018-06-27 Ali Zeydi Abdian , Afshin Behmaram , Gholam Hossein Fath-Tabar

In this paper, we investigate various algebraic and graph theoretic properties of the distance matrix of a graph. Two graphs are $D$-cospectral if their distance matrices have the same spectrum. We construct infinite pairs of $D$-cospectral…

We use the line digraph construction to associate an orthogonal matrix with each graph. From this orthogonal matrix, we derive two further matrices. The spectrum of each of these three matrices is considered as a graph invariant. For the…

Quantum Physics · Physics 2007-05-23 David Emms , Edwin R. Hancock , Simone Severini , Richard C. Wilson

We present the implementation of an algorithm for graph isomorphism testing, based on ideas about number of walks (of sufficiently large length) between vertices. The algorithm is expanded for strongly regular graphs (SRG-s) by testing the…

Combinatorics · Mathematics 2007-05-23 Michal Kaukic

A mixed graph $G$ is a graph obtained from a simple undirected graph by orientating a subset of edges. $G$ is self-converse if it is isomorphic to the graph obtained from $G$ by reversing each directed edge. For two mixed graphs $G$ and $H$…

Combinatorics · Mathematics 2019-12-02 Wei Wang , Lihong Qiu , Jianguo Qian , Wei Wang

We study cospectral vertices on finite graphs in relation to the echolocation problem on Riemannian manifolds. First, We prove a computationally simple criterion to determine whether two vertices are cospectral. Then, we use this criterion…

Combinatorics · Mathematics 2024-07-22 Shi-Lei Kong , Emmett L. Wyman , Yakun Xi

We address the correspondence search problem among multiple graphs with complex properties while considering the matching consistency. We describe each pair of graphs by combining multiple attributes, then jointly match them in a unified…

Computer Vision and Pattern Recognition · Computer Science 2018-03-16 Han-Mu Park , Kuk-Jin Yoon

We define a range of new coarse geometric invariants based on various graph-theoretic measures of complexity for finite graphs, including: treewidth, pathwidth, cutwidth and bandwidth. We prove that, for bounded degree graphs, these…

Metric Geometry · Mathematics 2025-08-07 Wanying Huang , David Hume , Samuel J. Kelly , Ryan Lam

The distance matrix of a connected graph is defined as the matrix in which the entries are the pairwise distances between vertices. The distance spectrum of a graph is the set of eigenvalues of its distance matrix. A graph is said to be…

Combinatorics · Mathematics 2022-01-10 Anuj Sakarda , Jerry Tan , Armaan Tipirneni

This paper presents a spectral framework for quantifying the differentiation between graph data samples by introducing a novel metric named Graph Geodesic Distance (GGD). For two different graphs with the same number of nodes, our framework…

Machine Learning · Computer Science 2025-08-18 Soumen Sikder Shuvo , Ali Aghdaei , Zhuo Feng

Let $G$ be a connected graph with vertex set $V(G)=\{v_{1},v_{2},...,v_{n}\}$. The distance matrix $D(G)=(d_{ij})_{n\times n}$ is the matrix indexed by the vertices of $G,$ where $d_{ij}$ denotes the distance between the vertices $v_{i}$…

Combinatorics · Mathematics 2018-01-30 Ruifang Liu , Jie Xue

A $\mathbb{T}$-gain graph is a simple graph in which a unit complex number is assigned to each orientation of an edge, and its inverse is assigned to the opposite orientation. The associated adjacency matrix is defined canonically, and is…

Combinatorics · Mathematics 2023-04-18 Aniruddha Samanta , M. Rajesh Kannan