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In this paper, we introduce the concept of $k$-integral graphs. A graph $\Gamma$ is called $k$-integral if the extension degree of the splitting field of the characteristic polynomial of $\Gamma$ over rational field $\mathbb Q$ is equal to…

Combinatorics · Mathematics 2025-08-06 Alireza Abdollahi , Majid Arezoomand , Tao Feng , Shixin Wang

The results of computer searches for large graphs with given (small) degree and diameter are presented. The new graphs are Cayley graphs of semidirect products of cyclic groups and related groups. One fundamental use of our ``dense graphs''…

Combinatorics · Mathematics 2008-02-03 Michael J. Dinneen , Paul R. Hafner

We investigate structural and combinatorial properties of Bi-Cayley graphs defined over cyclic groups of order $p^2q^2$, where $p$ and $q$ are distinct primes. We begin by describing their fundamental group-theoretic underpinnings. The main…

Combinatorics · Mathematics 2026-03-11 Iqbal Atmaja , Yeni Susanti , Ahmad Erfanian

In this paper, generalized Cayley graphs are studied. It is proved that every generalized Cayley graph of order 2p is a Cayley graph, where p is a prime. Special attention is given to generalized Cayley graphs on Abelian groups. It is…

Combinatorics · Mathematics 2015-12-02 Ademir Hujdurović , Klavdija Kutnar , Pawel Petecki , Anastasiya Tanana

In recent work, we study certain Cayley graphs associated with a finite commutative ring and their multiplicative subgroups. Among various results that we prove, we provide the necessary and sufficient conditions for such a Cayley graph to…

Combinatorics · Mathematics 2024-03-12 Tung T. Nguyen , Nguyen Duy Tân

In this paper, we introduce a new concept namely degree polynomial for vertices of a simple graph. This notion leads to a concept namely degree polynomial sequence which is stronger than the concept of degree sequence. After obtaining the…

Combinatorics · Mathematics 2020-09-02 Reza Jafarpour-Golzari

A \emph{mixed graph} is a graph with directed edges, called arcs, and undirected edges. A $k$-coloring of the vertices is proper if colors from ${1,2,...,k}$ are assigned to each vertex such that $u$ and $v$ have different colors if $uv$ is…

Combinatorics · Mathematics 2016-05-10 Matthias Beck , Daniel Blado , Joseph Crawford , Taina Jean-Louis , Michael Young

A discrete analog of quantum unique ergodicity was proved for Cayley graphs of quasirandom groups by Magee, Thomas and Zhao. They show that for large graphs there exist real orthonormal basis of eigenfunctions of the adjacency matrix such…

Mathematical Physics · Physics 2024-12-24 Jon Harrison , Clare Pruss

A graph $\G$ is {\em symmetric} or {\em arc-transitive} if its automorphism group $\Aut(\G)$ is transitive on the arc set of the graph, and $\G$ is {\em basic} if $\Aut(\G)$ has no non-trivial normal subgroup $N$ such that the quotient…

Combinatorics · Mathematics 2017-07-18 Da-Wei Yang , Yan-Quan Feng , Jin Ho Kwak , Jaeun Lee

In this paper a wide family of identifying codes over regular Cayley graphs of degree four which are built over finite Abelian groups is presented. Some of the codes in this construction are also perfect. The graphs considered include some…

Information Theory · Computer Science 2014-12-22 Cristóbal Camarero , Carmen Martínez , Ramón Beivide

A circulant graph is a Cayley graph of a finite cyclic group. The Weisfeiler-Leman-dimension of a circulant graph $X$ with respect to the class of all circulant graphs is the smallest positive integer~$m$ such that the $m$-dimensional…

Combinatorics · Mathematics 2024-10-01 Yulai Wu , Ilia Ponomarenko

The degree-diameter problem seeks to find the largest possible number of vertices in a graph having given diameter and given maximum degree. There has been much recent interest in the problem for mixed graphs, where we allow both undirected…

Combinatorics · Mathematics 2017-12-19 Grahame Erskine

A univariate graph polynomial P(G;X) is weakly distinguishing if for almost all finite graphs G there is a finite graph H with P(G;X)=P(H;X). We show that the clique polynomial and the independence polynomial are weakly distinguishing.…

Combinatorics · Mathematics 2023-06-22 Johann A. Makowsky , Vsevolod Rakita

Strongly regular Cayley graphs with Paley parameters over abelian groups of rank 2 were studied in [J.A Davis, Partial difference sets in p-groups, Arch.Math.63 (1994) 103-110; K.H Leung, S.L. Ma, Partial difference sets with Paley…

Combinatorics · Mathematics 2007-05-23 Yefim I. Leifman , Mikhail E. Muzychuk

We present simple graph-theoretic characterizations of Cayley graphs for left-cancellative monoids, groups, left-quasigroups and quasigroups. We show that these characterizations are effective for the end-regular graphs of finite degree.

Discrete Mathematics · Computer Science 2018-03-26 Didier Caucal

A connected symmetric graph of prime valency is {\em basic} if its automorphism group contains no nontrivial normal subgroup having more than two orbits. Let $p$ be a prime and $n$ a positive integer. In this paper, we investigate…

Combinatorics · Mathematics 2016-04-01 Yan-Quan Feng , Jin-Xin Zhou , Yan-Tao Li

We classify the distance-regular Cayley graphs with least eigenvalue $-2$ and diameter at most three. Besides sporadic examples, these comprise of the lattice graphs, certain triangular graphs, and line graphs of incidence graphs of certain…

Combinatorics · Mathematics 2016-04-28 Alireza Abdollahi , Edwin van Dam , Mojtaba Jazaeri

We define a weakly threshold sequence to be a degree sequence $d=(d_1,\dots,d_n)$ of a graph having the property that $\sum_{i \leq k} d_i \geq k(k-1)+\sum_{i > k} \min\{k,d_i\} - 1$ for all positive $k \leq \max\{i:d_i \geq i-1\}$. The…

Combinatorics · Mathematics 2023-06-22 Michael D. Barrus

Computing the clique number and chromatic number of a general graph are well-known NP-Hard problems. Codenotti et al. (Bruno Codenotti, Ivan Gerace, and Sebastiano Vigna. Hardness results and spectral techniques for combinatorial problems…

Combinatorics · Mathematics 2016-01-27 Chris Godsil , Brendan Rooney

The power graph $\mathcal{P}(G)$ of a finite group $G$ is the simple undirected graph whose vertex set is $G$, in which two distinct vertices are adjacent if one of them is an integral power of the other. For an integer $n\geq 2$, let $C_n$…

Combinatorics · Mathematics 2019-05-28 Ramesh Prasad Panda , Kamal Lochan Patra , Binod Kumar Sahoo