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Let $G(V, E)$ be a simple connected graph, with $|E| = \epsilon.$ In this paper, we define an edge-set graph $\mathcal G_G$ constructed from the graph $G$ such that any vertex $v_{s,i}$ of $\mathcal G_G$ corresponds to the $i$-th…

General Mathematics · Mathematics 2023-07-19 Johan Kok , N. K. Sudev , K. P. Chithra

The concept of Randic index has been extended recently for a digraph. We prove that $2R(G)\leq \mathcal{E}(G)\leq 2\sqrt{\Delta(G)} R(G)$, where $G$ is a digraph, and $R(G)$ denotes the Randic index, $\mathcal{E}(G)$ denotes the Nikiforov…

Spectral Theory · Mathematics 2021-07-01 Gerardo Arizmendi , Octavio Arizmendi

The virial theorem is applied to graphene and other Dirac Materials for systems close to the Dirac points where the dispersion relation is linear. From this, we find the exact form for the total energy given by $E = \mathcal{B}/r_s$ where…

Strongly Correlated Electrons · Physics 2016-06-29 J. Dustan Stokes , Hari P. Dahal , Alexander V. Balatsky , Kevin S. Bedell

The complexity of highly interconnected systems is rooted in the interwoven architecture defined by its connectivity structure. In this paper, we develop matrix energy of the underlying connectivity structure as a measure of topological…

Physics and Society · Physics 2016-08-31 Kaushik Sinha , Olivier L. de Weck

In this note a new measure of irregularity of a simple undirected graph $G$ is introduced. It is named the total irregularity of a graph and is defined as $\irr_t(G) = 1/2\sum_{u,v \in V(G)} |d_G(u)-d_G(v)|$, where $d_G(u)$ denotes the…

Discrete Mathematics · Computer Science 2015-03-20 Hosam Abdo , Darko Dimitrov

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

Let $x_1, x_2, \dots, x_n$ be the eigenvalues of a signed graph $\Gamma$ of order $n$. The energy of $\Gamma$ is defined as $E(\Gamma)=\sum^{n}_{j=1}|x_j|.$ Let $\mathcal{P}_n^4$ be obtained by connecting a vertex of the negative circle…

Combinatorics · Mathematics 2018-09-18 Dijian Wang , Yaoping Hou

A total weighting of a graph $G$ is a mapping $\phi$ that assigns a weight to each vertex and each edge of $G$. The vertex-sum of $v \in V(G)$ with respect to $\phi$ is $S_{\phi}(v)=\sum_{e\in E(v)}\phi(e)+\phi(v)$. A total weighting is…

Combinatorics · Mathematics 2024-01-17 Yunfang Tang , Yuting Yao

The total reciprocal edge-eccentricity is a novel graph invariant with vast potential in structure activity/property relationships. This graph invariant displays high discriminating power with respect to both biological activity and…

Combinatorics · Mathematics 2015-08-25 Shuchao Li , Lifang Zhao

The power graph of a group $G$ is the graph whose vertex set is $G$ and two distinct vertices are adjacent if one is a power of the other. This paper investigates the minimal separating sets of power graphs of finite groups. For power…

Combinatorics · Mathematics 2017-03-28 Ramesh Prasad Panda , K. V. Krishna

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

We establish a lower bound for the energy of a complex unit gain graph in terms of the matching number of its underlying graph, and characterize all the complex unit gain graphs whose energy reaches this bound.

Combinatorics · Mathematics 2020-05-06 Yuxuan Li

In this paper, we mainly study the trace norm of the adjacency matrix of a graph, also known as the energy of graph. We give the maximum trace norms for the graph and its complement. In fact, the above problem is stated and solved in a more…

Functional Analysis · Mathematics 2013-02-07 Vladimir Nikiforov , Xiying Yuan

Let $G$ be a simple graph of order $n$ with degree sequence $(d)=(d_1,d_2,\ldots,d_n)$ and conjugate degree sequence $(d^*)=(d_1^*,d_2^*,\ldots,d_n^*)$. In \cite{AkbariGhorbaniKoolenObudi2010,DasMojallalGutman2017} it was proven that…

Combinatorics · Mathematics 2018-08-17 Ercan Altınışık , Nurşah Mutlu Varlıoglu

In this paper, we obtain explicit formulae for the number of 7-cycles and the total number of paths of lengths 6 and 7 those contain a specific vertex $v_{i}$ in a simple graph G, in terms of the adjacency matrix and with the help of…

Combinatorics · Mathematics 2015-03-12 Nazanin Movarraei

Let $G$ be a graph of order $n$ with eigenvalues $\lambda_1 \geq \cdots \geq\lambda_n$. Let \[s^+(G)=\sum_{\lambda_i>0} \lambda_i^2, \qquad s^-(G)=\sum_{\lambda_i<0} \lambda_i^2.\] The smaller value, $s(G)=\min\{s^+(G), s^-(G)\}$ is called…

Combinatorics · Mathematics 2024-09-30 Saieed Akbari , Hitesh Kumar , Bojan Mohar , Shivaramakrishna Pragada

Given a group $G$, we define the power graph $\mathcal{P}(G)$ as follows: the vertices are the elements of $G$ and two vertices $x$ and $y$ are joined by an edge if $\langle x\rangle\subseteq \langle y\rangle$ or $\langle y\rangle\subseteq…

Group Theory · Mathematics 2017-05-16 A. R. Moghaddamfar , S. Rahbariyan , S. Navid Salehy , S. Nima Salehy

The $G$-graph $\Gamma(G,S)$ is a graph from the group $G$ generated by $S\subseteq G$, where the vertices are the right cosets of the cyclic subgroups $\langle s \rangle, s\in S$ with $k$-edges between two distinct cosets if there is an…

Combinatorics · Mathematics 2016-09-05 Lord Clifford Kavi

Let $G$ be a graph on $n$ vertices with independence number $\alpha(G)$. Let $\mathcal{E}(G)$ be the energy of a graph, defined as the sum of the absolute values of the adjacency eigenvalues of $G$. Using Graffiti, Fajtlowicz conjectured in…

Combinatorics · Mathematics 2025-09-09 Aida Abiad , Gabriel Coutinho , Emanuel Juliano , Luuk Reijnders

The enhanced power graph of a finite group $G$, denoted by $\mathcal{P}_E(G)$, is the simple undirected graph whose vertex set is $G$ and two distinct vertices $x, y$ are adjacent if $x, y \in \langle z \rangle$ for some $z \in G$. In this…

Group Theory · Mathematics 2022-07-13 Parveen , Jitender Kumar , Siddharth Singh , Xuanlong Ma