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The energy of a graph is the sum of the moduli of the eigenvalues of its adjacency matrix. We study the energy of integral circulant graphs, also called gcd graphs, which can be characterized by their vertex count n and a set D of divisors…

Combinatorics · Mathematics 2018-08-21 Jürgen W. Sander , Torsten Sander

The energy of a graph is the sum of the moduli of the eigenvalues of its adjacency matrix. We study the energy of integral circulant graphs, also called gcd graphs, which can be characterized by their vertex count $n$ and a set $\cal D$ of…

Combinatorics · Mathematics 2018-08-21 Jürgen W. Sander , Torsten Sander

A digraph with self-loops $D_S$ with vertex set $\mathcal{V}$ is a simple digraph with a self-loop attached at every vertex in $S \subset \mathcal{V}.$ In this paper, we study the energy $E(D_S)$ of $D_S$ and its properties, which extend…

Combinatorics · Mathematics 2025-08-13 Kevin Fung , Johnny Lim

Let $p$ and $q$ be distinct primes. The \textit{semiprime divisor function graph} denoted by $G_{D(pq)}$, is the graph with vertex set $V(G_{D(pq)})=\{1,p,q,pq\}$ and edge set $E(G_{D(pq)})=\{\{1,p\}, \{1,q\},\{1,pq\},\{p,pq\},\{q,pq\}\}$.…

Combinatorics · Mathematics 2021-11-23 John Rafael M. Antalan , Jerwin G. De Leon , Regine P. Dominguez

Let G be a simple graph on n vertices with vertex set V(G). The energy of G, denoted by, $\mathcal{E}(G)$ is the sum of all absolute values of the eigenvalues of the adjacency matrix $A(G)$. It is the first eigenvalue-based topological…

Combinatorics · Mathematics 2024-05-27 B. R. Rakshith , Kinkar Chandra Das , B. J. Manjunatha

The energy of a graph was introduced by {\sc Gutman} in 1978 as the sum of the absolute values of the eigenvalues of its adjacency matrix. We study the energy of integral circulant graphs, also called gcd graphs, which can be characterized…

Combinatorics · Mathematics 2011-09-19 J. W. Sander , T. Sander

Graph energy has been widely investigated in spectral graph theory. However, the manner in which this energy is distributed among individual vertices has received attention only more recently, following the introduction of energy of a…

Combinatorics · Mathematics 2026-03-23 Harshitha A , Madhumitha K , Sabitha D'Souza

The energy of a vertex $v_i$ in a graph $G$ is defined as $\mathcal{E}_G(v_i) = |A|_{ii}$, where $A$ is the adjacency matrix of $G$, $A^*$ denotes the conjugate transpose of $A$, and $|A| = (AA^*)^{1/2}$. The total energy of the graph,…

Combinatorics · Mathematics 2025-08-19 H. M. Nagesh , U. Vijaya Chandra Kumar , N. Narahari

Let $G_{S}$ be a graph with $n$ vertices obtained from a simple graph $G$ by attaching one self-loop at each vertex in $S \subseteq V(G)$. The energy of $G_{S}$ is defined by Gutman et al. as $E(G_{S})=\sum_{i=1}^{n}\left| \lambda_{i}…

Combinatorics · Mathematics 2024-06-18 Minghua Li , Yue Liu

The power graph $\mathcal{P}(G)$ of a group $G$ is the graph whose vertex set is $G$, having an edge between two distinct vertices if one is the power of the other. The directed power graph $\vec{\mathcal{P}}(G)$ of a group $G$ is the…

Group Theory · Mathematics 2022-08-30 Nicolas Pinzauti , Daniela Bubboloni

In this paper, we investigate the energy of a weighted random graph $G_p(f)$ in $G_{n,p}(f)$, in which each edge $ij$ takes the weight $f(d_i,d_j)$, where $d_v$ is a random variable, the degree of vertex $v$ in the random graph $G_p$ of the…

Combinatorics · Mathematics 2020-03-04 Xueliang Li , Yiyang Li , Jiarong Song

In this paper, we introduce the notion of an energy graph as a simple, directed and vertex labeled graph $G$ such that the arcs $(v_i, v_j) \notin A(G)$ if $i > j$ for all distinct pairs $v_i,v_j$ and at least one vertex $v_k$ exists such…

General Mathematics · Mathematics 2016-10-13 Johan Kok , N. K. Sudev , K. P. Chithra , U. Mary

Harshitha et al. recently introduced Seidel energy of graphs with self loops. In this paper, we extend some of their results by giving a necessary and sufficient condition for the Seidel energy of a looped graph to be equal to the Seidel…

General Mathematics · Mathematics 2026-02-02 Kalpesh M. Popat , Irena M. Jovanovic

For a graph $G$ with vertex set $V(G)=\{v_1, v_2, \cdots, v_n\}$, the extended double cover $G^*$ is a bipartite graph with bipartition (X, Y), $X=\{x_1, x_2, \cdots, x_n\}$ and $Y=\{y_1, y_2, \cdots, y_n\}$, where two vertices $x_i$ and…

Combinatorics · Mathematics 2013-10-14 S. Pirzada , Hilal A Ganie

Graph energy is the energy of the matrix representation of the graph, where the energy of a matrix is the sum of singular values of the matrix. Depending on the definition of a matrix, one can contemplate graph energy, Randi\'c energy,…

Social and Information Networks · Computer Science 2019-02-12 Mikołaj Morzy , Tomasz Kajdanowicz

The extended adjacency matrix of a graph with $n$ vertices is a real symmetric matrix of order $n\times n$ whose $(i,j)$-th entry is the average of the ratio of the degree of the vertex $i$ to that of the vertex $j$ and its reciprocal when…

Combinatorics · Mathematics 2025-01-22 Abujafar Mandal , Sk. Md. Abu Nayeem

Suppose G is an n-vertex simple graph with vertex set {v1,..., vn} and d(i), i = 1,..., n, is the degree of vertex vi in G. The ISI matrix S(G) = [sij] of G is a square matrix of order n and is defined by sij = d(i)d(j)/d(i)+d(j) if the…

Combinatorics · Mathematics 2019-05-13 Sumaira Hafeez , Rashid Farooq

The difference graph $D(G)$ of a finite group $G$ is the difference of enhanced power graph of $G$ and power graph of $G$, with all isolated vertices are removed. In this paper we study the connectedness and perfectness of $D(G)$ with…

Combinatorics · Mathematics 2024-08-23 Sucharita Biswas , Peter J. Cameron , Angsuman Das , Hiranya Kishore Dey

For a given graph \( G \), let \( G^{(j)} \) denote the graph obtained by the deletion of vertex \( v_j \) from \( G \). The difference \( \mathscr{E}(G) - \mathscr{E}(G^{(j)}) \) quantifies the change in the energy of \( G \) upon the…

Combinatorics · Mathematics 2026-04-17 Cahit Dede , Kalpesh M. Popat

The graph $G_\sigma$ is obtained from graph $G$ by attaching self loops on $\sigma$ vertices. The energy $ E(G_\sigma)$ of the graph $G_\sigma$ with order $n$ and eigenvalues $\lambda_1,\lambda_2,\dots,\lambda_n$ is defined as $…

Combinatorics · Mathematics 2026-04-22 Kalpesh M. Popat , Kunal R. Shingala
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