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Let $G$ be an unicyclic graph of order $n$ and let $Q_G(x)= det(xI-Q(G))={matrix} \sum_{i=1}^n (-1)^i \varphi_i x^{n-i}{matrix}$ be the characteristic polynomial of the signless Laplacian matrix of a graph $G$. We give some transformations…

Combinatorics · Mathematics 2012-12-21 Jie Zhang , Xiao-Dong Zhang

Graphs with diverse structural characteristics play a central role in modelling and optimization tasks. The ability to generate different types of graphs that exhibit shared properties is likewise essential for algorithm selection and…

Neural and Evolutionary Computing · Computer Science 2026-03-31 Hendrik Richter , Frank Neumann

We study the sets of inertias achieved by Laplacian matrices of weighted signed graphs. First we characterize signed graphs with a unique Laplacian inertia. Then we show that there is a sufficiently small perturbation of the nonzero weights…

Spectral Theory · Mathematics 2019-12-10 Keivan Hassani Monfared , Gary MacGillivray , Dale D. Olesky , Pauline van den Driessche

In this paper we obtain bounds on a very general class of distance-based topological indices of graphs, which includes the Wiener index, defined as the sum of the distances between all pairs of vertices of the graph, and most…

Combinatorics · Mathematics 2024-11-21 Peter Dankelmann

Let $D(G)$ denote the distance matrix of a connected graph $G$ with $n$ vertices. The distance spectral gap of a graph $G$ is defined as $\delta_{D^G} = \rho_1 - \rho_2$, where $\rho_1$ and $\rho_2$ represent the largest and second largest…

Combinatorics · Mathematics 2025-02-12 Haritha T , Chithra A.

Given a positive-weighted simple connected graph with $m$ vertices, labelled by the numbers $1,\ldots,m$, we can construct an $m \times m$ matrix whose entry $(i,j)$, for any $i,j\in\{1,\dots,m\}$, is the minimal weight of a path between…

Combinatorics · Mathematics 2020-03-02 Elena Rubei , Dario Villanis Ziani

A gain graph is a triple (G,h,H), where G is a connected graph with an arbitrary, but fixed, orientation of edges, H is a group, and h is a homomorphism from the free group on the edges of G to H. A gain graph is called balanced if the…

Combinatorics · Mathematics 2010-01-24 Konstantin Rybnikov , Thomas Zaslavsky

We study the discrete Gel'fand's inverse boundary spectral problem of determining a finite weighted graph. Suppose that the set of vertices of the graph is a union of two disjoint sets: $X=B\cup G$, where $B$ is called the set of the…

Spectral Theory · Mathematics 2023-03-06 Emilia Blåsten , Hiroshi Isozaki , Matti Lassas , Jinpeng Lu

Representing graphs as quantum states is becoming an increasingly important approach to study entanglement of mixed states, alternate to the standard linear algebraic density matrix-based approach of study. In this paper, we propose a…

Quantum Physics · Physics 2017-03-24 Bibhas Adhikari , Subhashish Banerjee , Satyabrata Adhikari , Atul Kumar

Let $D(G)$ be the distance matrix of a simple connected graph $G$. The Hadamard product $D(G)~\circ~ D(G)$ is called the squared distance matrix of $G$, and is denoted by $\Delta(G)$. A simple connected graph is called a starlike block…

Combinatorics · Mathematics 2025-09-26 Joyentanuj Das , Sumit Mohanty

Let $\Gamma$ be a locally finite graph, $L$ the normalized Laplacian of $\Gamma$. If $\Gamma$ is uniformy locally finite, i.e. if each vertex has no more than $d$ adjacent vertices, then the matrix of $L$ (with respect to the standard…

Combinatorics · Mathematics 2018-08-14 Vladimir Manuilov

The universal adjacency matrix $U$ of a graph $\Gamma$, with adjacency matrix $A$, is a linear combination of $A$, the diagonal matrix $D$ of vertex degrees, the identity matrix $I$, and the all-1 matrix $J$ with real coefficients, that is,…

Combinatorics · Mathematics 2019-12-11 C. Dalfó , M. A. Fiol , S. Pavlíková , J. Širáň

The ubiquity of massive graph data sets in numerous applications requires fast algorithms for extracting knowledge from these data. We are motivated here by three electrical measures for the analysis of large small-world graphs $G = (V, E)$…

Data Structures and Algorithms · Computer Science 2021-02-09 Eugenio Angriman , Maria Predari , Alexander van der Grinten , Henning Meyerhenke

We introduce QuaterGCN, a spectral Graph Convolutional Network (GCN) with quaternion-valued weights at whose core lies the Quaternionic Laplacian, a quaternion-valued Laplacian matrix by whose proposal we generalize two widely-used…

Machine Learning · Computer Science 2024-01-01 Stefano Fiorini , Stefano Coniglio , Michele Ciavotta , Enza Messina

The enhanced power graph of a group $G$ is a simple undirected graph with vertex set $G$ and two vertices are adjacent if they belong to same cyclic subgroup. In this paper, we study distant properties and detour distant properties such as…

Group Theory · Mathematics 2021-08-31 Parveen , Sandeep Dalal , Jitender Kumar

A signed graph has edge signs. A gain graph has oriented edge gains drawn from a group. We define the combination of the two for the abelian case, in which each oriented edge of a signed graph has a gain from an abelian group, concentrating…

Combinatorics · Mathematics 2022-06-22 Laura Anderson , Ting Su , Thomas Zaslavsky

Let $D$ be an digraph of order $n$ with adjacency matrix $A(D)$ and outdegree matrix $\Delta^+=\Delta^+(D)$. Then the Laplacian and signless Laplacian matrices of $D$ are respectively defined as $L(D)=\Delta^+-A(D)$ and…

Combinatorics · Mathematics 2026-04-07 Mushtaq A. Bhat , Peer Abdul Manan

The average distance of a vertex $v$ of a connected graph $G$ is the arithmetic mean of the distances from $v$ to all other vertices of $G$. The proximity $\pi(G)$ and the remoteness $\rho(G)$ of $G$ are the minimum and the maximum of the…

Combinatorics · Mathematics 2023-06-22 Peter Dankelmann , Sonwabile Mafunda , Sufiyan Mallu

Given a sample from a probability measure with support on a submanifold in Euclidean space one can construct a neighborhood graph which can be seen as an approximation of the submanifold. The graph Laplacian of such a graph is used in…

Statistics Theory · Mathematics 2007-06-27 Matthias Hein , Jean-Yves Audibert , Ulrike von Luxburg

Let $G$ be a simple graph with adjacency matrix $A(G)$, signless Laplacian matrix $Q(G)$, degree diagonal matrix $D(G)$ and let $l(G)$ be the line graph of $G$. In 2017, Nikiforov defined the $A_\alpha$-matrix of $G$, $A_\alpha(G)$, as a…

Discrete Mathematics · Computer Science 2024-02-26 Joao Domingos Gomes da Silva Junior , Carla Silva Oliveira , Liliana Manuela Gaspar C. da Costa