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The eccentricity matrix $\varepsilon(G)$ of a graph $G$ is obtained from the distance matrix of $G$ by retaining the largest distances in each row and each column, and leaving zeros in the remaining ones. The eccentricity energy of $G$ is…

Combinatorics · Mathematics 2021-07-08 Iswar Mahato , M. Rajesh Kannan

In this paper, first we compute the energy of a special partitioned matrix under some cases. As a consequence, we obtain the reciprocal distance energy of the complete multipartite graph and also we give various other energies of complete…

Combinatorics · Mathematics 2022-04-22 Rakshith B. R. , B. J. Manjunatha

The energy of a graph is the sum of the absolute values of the eigenvalues of its adjacency matrix. This note is about the energy of regular graphs. It is shown that graphs that are close to regular can be made regular with a negligible…

Combinatorics · Mathematics 2016-05-10 V. Nikiforov

We prove that, for any graph $G$, its graph energy is at least twice the Randic index. We show that equality holds if and only if $G$ is the union of complete bipartite graphs.

Combinatorics · Mathematics 2020-09-18 Gerardo Arizmendi , Octavio Arizmendi

For a simple graph $G=(V,E)$ with eigenvalues of the adjacency matrix $\lambda_{1}\geq\lambda_{2}\geq\cdots\geq\lambda_{n}$, the energy of the graph is defined by $E(G)=\sum_{j=1}^{n}|\lambda_{j}|$. Myriads of papers have been published in…

Combinatorics · Mathematics 2017-04-05 Ernesto Estrada , Michele Benzi

The eccentricity matrix of a graph is obtained from the distance matrix by keeping the largest entries in their row or column, and the remaining entries are replaced by zeros. The eccentricity energy of a graph is the sum of the absolute…

Combinatorics · Mathematics 2026-03-02 Anjitha Ashokan , Chithra A

The energy of a graph is defined as the sum of the absolute values of the eigenvalues of the graph. In this paper, we present a new method to compare the energies of two $k$-subdivision bipartite graphs on some cut edges. As the…

Combinatorics · Mathematics 2011-11-10 Hai-Ying Shan , Jia-Yu Shao , Li Zhang , Chang-Xiang He

Let $G$ be a graph with $n$ vertices and $m$ edges. The energy $E$ of the graph $G$ is defined as the sum of the moduli of the adjacency eigenvalues $\lambda_{1} \geq \lambda_{2} \geq \ldots \geq \lambda_{n}$ of $G$: $$…

Combinatorics · Mathematics 2014-09-04 Felix Goldberg

The article presents weighted adjacency spectrum of complete multipartite graphs, characterize its families with three distinct eigenvalues and identifies integral matrices. Also, we observe that for almost all weighted matrices, the energy…

Combinatorics · Mathematics 2026-03-11 Bilal Ahmad Rather , Hilal Ahmad Ganie

In 1970s, Gutman introduced the concept of the energy $\En(G)$ for a simple graph $G$, which is defined as the sum of the absolute values of the eigenvalues of $G$. This graph invariant has attracted much attention, and many lower and upper…

Combinatorics · Mathematics 2009-09-29 Wenxue Du , Xueliang Li , Yiyang Li

The energy of a graph $G$ is the sum of the absolute values of the eigenvalues of the adjacency matrix of $G$. Let $s^+(G), s^-(G)$ denote the sum of the squares of the positive and negative eigenvalues of $G$, respectively. It was…

Combinatorics · Mathematics 2025-11-10 Aida Abiad , Leonardo de Lima , Dheer Noal Desai , Krystal Guo , Leslie Hogben , Jose Madrid

Let G be a simple graph of order $n$ and $\mu_1,\mu_2,\ldots,\mu_n$ the roots of its matching polynomial. The matching energy of $G$ is defined as the sum $\sum_{i=1}^n|\mu_i|$. Let $K_{n-1,1}^k$ be the graph obtained from $K_1\cup K_{n-1}$…

Combinatorics · Mathematics 2014-05-08 Shengjin Ji , Hongping Ma

The energy of a graph G, denoted by E(G), is defined as the sum of the absolute values of all eigenvalues of G. It is proved that E(G)>= 2(n-\chi(\bar{G}))>= 2(ch(G)-1) for every graph G of order n, and that E(G)>= 2ch(G) for all graphs G…

Combinatorics · Mathematics 2007-12-07 Saieed Akbari , Ebrahim Ghorbani

Given a graph $M,$ path eigenvalues are eigenvalues of its path matrix. The path energy of a simple graph $M$ is equal to the sum of the absolute values of the path eigenvalues of the graph $M$ (Shikare et. al, 2018). We have discovered new…

Combinatorics · Mathematics 2024-05-24 Amol P. Narke , Prashant P. Malavadkar , Maruti M. Shikare

The energy of a simple graph $G$, denoted by $E(G)$, is defined as the sum of the absolute values of all eigenvalues of its adjacency matrix. Let $C_n$ denote the cycle of order $n$ and $P^{6,6}_n$ the graph obtained from joining two cycles…

Combinatorics · Mathematics 2011-02-18 Bofeng Huo , Shengjin Ji , Xueliang Li , Yongtang Shi

The energy $E(G)$ of a graph $G$ is defined as the sum of the absolute values of its eigenvalues. Let $S_2$ be the star of order 2 (or $K_2$) and $Q$ be the graph obtained from $S_2$ by attaching two pendent edges to each of the end…

Combinatorics · Mathematics 2009-07-10 Xueliang Li , Hongping Ma

The energy $E$ of a graph is defined to be the sum of the absolute values of its eigenvalues. Nikiforov in {\it ``V. Nikiforov, The energy of $C_4$-free graphs of bounded degree, Lin. Algebra Appl. 428(2008), 2569--2573"} proposed two…

Combinatorics · Mathematics 2009-06-05 Xueliang Li , Jianxi Liu

Let $G$ be a simple graph of order $n$. The energy $E(G)$ of the graph $G$ is the sum of the absolute values of the eigenvalues of $G$. The Randi\'{c} matrix of $G$, denoted by $R(G)$, is defined as the $n\times n$ matrix whose…

Combinatorics · Mathematics 2014-12-30 Saeid Alikhani , Nima Ghanbari

The sum of the absolute values of the eigenvalues of a graph is called the energy of the graph. We study the problem of finding graphs with extremal energy within specified classes of graphs. We develop tools for treating such problems and…

Combinatorics · Mathematics 2007-10-31 Dragos Cvetkovic , Jason Grout

The eccentricity (anti-adjacency) matrix $\varepsilon(G)$ of a graph $G$ is obtained from the distance matrix by retaining the eccentricities in each row and each column. The $\varepsilon$-eigenvalues of a graph $G$ are those of its…

Combinatorics · Mathematics 2020-02-18 Fernando Tura
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