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In this paper,we construct some directed strongly regular Cayley graphs on dihedral groups,these generalizes some earlier constructions.We also characterize some certain directed strongly regular Cayley graphs on dihedral groups…

Combinatorics · Mathematics 2019-09-20 Yiqin He , Bicheng Zhang , Rongquan Feng

Perfect code in Cayley graphs and Cayley sum graphs is studied extensively in recent years. In this paper, we consider perfect code in generalized Cayley graphs.

Combinatorics · Mathematics 2024-01-23 Liao Qianfen , Liu Weijun

The distinguishing chromatic number of a graph $G$ is the smallest number of colors needed to properly color the vertices of $G$ so that the trivial automorphism is the only symmetry of $G$ that preserves the coloring. We investigate the…

Combinatorics · Mathematics 2023-03-27 Michael D. Barrus , Jean Guillaume , Benjamin Lantz

A dynamic coloring of a graph $G$ is a proper coloring such that for every vertex $v\in V(G)$ of degree at least 2, the neighbors of $v$ receive at least 2 colors. In this paper we present some upper bounds for the dynamic chromatic number…

Combinatorics · Mathematics 2009-08-19 Meysam Alishahi

We study the existence of periodic colorings and orientations in locally finite graphs. A coloring or orientation of a graph $G$ is periodic if the resulting colored or oriented graph is quasi-transitive, meaning that $V(G)$ has finitely…

In the paper we give a lower bound for the number of vertices of a given graph using its chromatic number. We find the graphs for which this bound is exact. The results are applied in the theory of Foklman numbers.

Combinatorics · Mathematics 2010-02-24 Nedyalko Dimov Nenov

We define several new types of quantum chromatic numbers of a graph and characterise them in terms of operator system tensor products. We establish inequalities between these chromatic numbers and other parameters of graphs studied in the…

Operator Algebras · Mathematics 2013-11-28 Vern I. Paulsen , Ivan G. Todorov

In this article we complete the work of enumerating typical abelian coverings of Cayley graphs, by reducing the problem to enumerating certain subgroups of finite abelian groups.

Combinatorics · Mathematics 2024-02-27 Haimiao Chen

Let $G$ be a simple graph. A total dominator coloring of $G$ is a proper coloring of the vertices of $G$ in which each vertex of the graph is adjacent to every vertex of some color class. The total dominator chromatic number $\chi_d^t(G)$…

Combinatorics · Mathematics 2015-11-06 Saeid Alikhani , Nima Ghanbari

Various results ensure the existence of large complete bipartite graphs in properly colored graphs when some condition related to a topological lower bound on the chromatic number is satisfied. We generalize three theorems of this kind,…

Combinatorics · Mathematics 2017-04-04 Meysam Alishahi , Hossein Hajiabolhassan , Frédéric Meunier

We obtain a complete classification of graph products of finite abelian groups whose Cayley graphs with respect to the standard presentations are planar.

Group Theory · Mathematics 2019-02-28 Olga Varghese

The dichromatic number and the diachromatic number are generalizations of the chromatic number and the achromatic number for digraphs considering acyclic colorings. In this paper, we determine the diachromatic number of digraphs arising…

Combinatorics · Mathematics 2024-12-05 Mika Olsen , Christian Rubio-Montiel , Alejandra Silva-Ramírez

Conventional Ramsey-theoretic investigations for edge-colourings of complete graphs are framed around avoidance of certain configurations. Motivated by considerations arising in the field of Qualitative Reasoning, we explore edge colourings…

Combinatorics · Mathematics 2022-01-11 Badriah Al Juaid , Marcel Jackson , James Koussas , Tomasz Kowalski

Erd\H{o}s proved that there are graphs with arbitrarily large girth and chromatic number. We study the extension of this for generalized chromatic numbers.

Combinatorics · Mathematics 2007-05-23 Béla Bollobás , Douglas B. West

We construct, for each countable ordinal $\xi$, a closed graph with Borel chromatic number two and Baire class $\xi$ chromatic number $\aleph\_0$.

Logic · Mathematics 2014-12-16 Dominique Lecomte , Miroslav Zeleny

We report about the results of the application of modern computer algebra tools for construction of directed strongly regular graphs. The suggested techniques are based on the investigation of non-commutative association schemes and Cayley…

Combinatorics · Mathematics 2015-03-30 Štefan Gyürki , Mikhail Klin

Colouring the vertices of a graph $G$ according to certain conditions can be considered as a random experiment and a discrete random variable $X$ can be defined as the number of vertices having a particular colour in the proper colouring of…

General Mathematics · Mathematics 2017-08-17 K. P. Chithra , N. K. Sudev , S. Satheesh , K. A. Germina , Johan Kok

A total dominator coloring of a graph $G$ is a proper coloring of $G$ in which each vertex of the graph is adjacent to every vertex of some color class. The total dominator chromatic number $\chi_d^t(G)$ of $G$ is the minimum number of…

Combinatorics · Mathematics 2019-06-12 Adel P. Kazemi

WE study the clique number and the chromatic number of generalized Sierpinski graphs in which the base graph is an arbitrary simple graph.

Combinatorics · Mathematics 2024-05-30 Fatemeh Attarzadeh , Ahmad Abbasi , Ali Behtoei

In this paper, we characterize some certain directed strongly regular Cayley graphs on Dihedral groups $D_{n}$, where $n\geqslant 3$ is a positive integer.

Combinatorics · Mathematics 2018-07-25 Yiqin He , Bicheng Zhangb , Rongquan Feng
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