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A circulant graph is a simple graph whose adjacency matrix can be represented in the form of a circulant matrix, while a nut graph is considered to be a graph whose null space is spanned by a single full vector. In a previous study by…

Combinatorics · Mathematics 2026-01-26 Ivan Damnjanović

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 extend the notions of the m-splitting graph Sm(G) and the m-shadow graph Dm(G) to introduce two new graph operations: the (p, q)-generalized splitting graph Sp,q(G) and the (c, k)-shadow-splitting graph Hc,k(G). We derive the adjacency…

Combinatorics · Mathematics 2026-04-02 Ronak B. Dudhat , Vinodray J. Kaneria , Kalpesh M. Popat

Clustering in directed graphs remains a fundamental challenge due to the asymmetry in edge connectivity, which limits the applicability of classical spectral methods originally designed for undirected graphs. A common workaround is to…

For a connected graph, the distance spectral radius is the largest eigenvalue of its distance matrix, and the distance energy is defined as the sum of the absolute values of the eigenvalues of its distance matrix. We establish lower and…

Combinatorics · Mathematics 2011-01-25 Bo Zhou , Aleksandar Ilic

For every integer d > 9, we construct infinite families {G_n}_n of d+1-regular graphs which have a large girth > log_d |G_n|, and for d large enough > 1,33 log_d |G_n|. These are Cayley graphs on PGL_2(q) for a special set of d+1 generators…

Combinatorics · Mathematics 2015-01-05 Xavier Dahan

The enhanced power graph $\mathcal{P}_e(G)$ of a group $G$ is a graph with vertex set $G$ and two vertices are adjacent if they belong to the same cyclic subgroup. In this paper, we consider the minimum degree, independence number and…

Group Theory · Mathematics 2020-01-27 Ramesh Prasad Panda , Sandeep dalal , Jitender Kumar

We propose new families of graphs which exhibit quantum perfect state transfer. Our constructions are based on the join operator on graphs, its circulant generalizations, and the Cartesian product of graphs. We build upon the results of…

Quantum Physics · Physics 2010-01-09 R. J. Angeles-Canul , R. Norton , M. Opperman , C. Paribello , M. Russell , C. Tamon

The Directed Power Graph of a group is a graph whose vertex set is the elements of the group, with an edge from $x$ to $y$ if $y$ is a power of $x$. The \textit{Power Graph} of a group can be obtained from the directed power graph by…

Combinatorics · Mathematics 2020-12-07 Amrita Acharyya , Allen Williams

In this paper, we determine the Randic' energy of the m-splitting graph, the m-shadow graph and the m-duplicate graph of a given graph, m being an arbitrary integer. Our results allow the construction of an infinite sequence of graphs…

Combinatorics · Mathematics 2021-05-18 Jahfar T K , Chithra A

There has been a great deal of attention recently to graphs whose vertex set is a group, defined using the group structure. (The commuting graph, where two elements are joined if they commute, is the oldest and most famous example.) The…

Combinatorics · Mathematics 2026-02-03 Peter J. Cameron

The two graphs of the title both have vertex set G. In the intersection power graph, x and y are joined if some non-identity element is a power of both; in the power graph, x and y joined if one is a power of the other. Thus the power graph…

Combinatorics · Mathematics 2025-09-05 Sudip Bera , Peter J. Cameron

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

The undirected power graph (or simply power graph) of a group $G$, denoted by $P(G)$, is a graph whose vertices are the elements of the group $G$, in which two vertices $u$ and $v$ are connected by an edge between if and only if either…

Combinatorics · Mathematics 2023-05-09 Pallabi Manna , Peter J. Cameron , Ranjit Mehatari

A graph is called integral if all its eigenvalues are integers. A Cayley graph is called normal if its connection set is a union of conjugacy classes. We show that a non-empty integral normal Cayley graph for a group of odd order has an odd…

Combinatorics · Mathematics 2023-12-21 Arnbjörg Soffía Árnadóttir , Chris Godsil

Let $G = K_{n_1,n_2,\cdots,n_t}$ be a complete $t$-partite graph on $n=\sum_{i=1}^t n_i$ vertices. The distance between vertices $i$ and $j$ in $G$, denoted by $d_{ij}$ is defined to be the length of the shortest path between $i$ and $j$.…

Combinatorics · Mathematics 2022-12-02 Joyentanuj Das , Sumit Mohanty

In this paper, we consider the Randi\'{c} energy $RE$ of simple connected graphs. We provide upper bounds for $RE$ in terms of the number of vertices and the nullity of the graph. We present families of graphs that satisfy the Conjecture…

Combinatorics · Mathematics 2018-11-22 Luiz Emilio Allem , Gonzalo Molina , Adrián Pastine

Graph connectivity serves as a fundamental metric for evaluating the reliability and fault tolerance of interconnection networks. To more precisely characterize network robustness, the concept of cyclic connectivity has been introduced,…

Combinatorics · Mathematics 2025-11-04 Ting Tian , Shumin Zhang , Bo Zhu

We study two families of cyclotomic graphs and perfect codes in them. They are Cayley graphs on the additive group of $\mathbb{Z}[\zeta_m]/A$, with connection sets $\{\pm (\zeta_m^i + A): 0 \le i \le m-1\}$ and $\{\pm (\zeta_m^i + A): 0 \le…

Combinatorics · Mathematics 2018-09-27 Sanming Zhou

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