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Let $G$ be an edge-colored graph on $n$ vertices. For a vertex $v$, the \emph{color degree} of $v$ in $G$, denoted by $d^c(v)$, is the number of colors appearing on the edges incident with $v$. Denote by $\delta^c(G)=\min\{d^c(v):v\in…

Combinatorics · Mathematics 2025-10-14 Xiaozheng Chen , Bo Ning

Let $c$ be an edge-coloring of the complete $n$-vertex graph $K_n$. The problem of finding properly colored and rainbow Hamilton cycles in $c$ was initiated in 1976 by Bollob\'as and Erd\H os and has been extensively studied since then.…

Combinatorics · Mathematics 2016-10-27 Nina Kamčev , Benny Sudakov , Jan Volec

For a proper vertex coloring $c$ of a graph $G$, let $\varphi_c(G)$ denote the maximum, over all induced subgraphs $H$ of $G$, the difference between the chromatic number $\chi(H)$ and the number of colors used by $c$ to color $H$. We…

Combinatorics · Mathematics 2014-11-19 N. R. Aravind , Subrahmanyam Kalyanasundaram , R. B. Sandeep , Naveen Sivadasan

A matching $M$ in a graph $G$ is {\em semistrong} if every edge of $M$ has an endvertex of degree one in the subgraph induced by the vertices of $M$. A {\em semistrong edge-coloring} of a graph $G$ is a proper edge-coloring in which every…

Combinatorics · Mathematics 2023-12-15 Borut Lužar , Martina Mockovčiaková , Roman Soták

A path in an edge-colored graph $G$ is rainbow if no two edges of it are colored the same. The graph $G$ is rainbow-connected if there is a rainbow path between every pair of vertices. If there is a rainbow shortest path between every pair…

Discrete Mathematics · Computer Science 2023-06-22 Melissa Keranen , Juho Lauri

An \emph{interval $t$-coloring} of a multigraph $G$ is a proper edge coloring with colors $1,\dots,t$ such that the colors on the edges incident to every vertex of $G$ are colored by consecutive colors. A \emph{cyclic interval $t$-coloring}…

Combinatorics · Mathematics 2016-11-22 Carl Johan Casselgren , Hrant H. Khachatrian , Petros A. Petrosyan

A vertex coloring of a graph G is called a 2-distance coloring if any two vertices at a distance at most 2 from each other receive different colors. Suppose that G is a planar graph with a maximum degree at most 5. We prove that G admits a…

Combinatorics · Mathematics 2025-08-21 Zakir Deniz

Let $c$ be a proper edge colouring of a graph $G=(V,E)$ with integers $1,2,\ldots,k$. Then $k\geq \Delta(G)$, while by Vizing's theorem, no more than $k=\Delta(G)+1$ is necessary for constructing such $c$. On the course of investigating…

Discrete Mathematics · Computer Science 2018-03-07 Marthe Bonamy , Jakub Przybyło

The `Conflict-Free Open (Closed) Neighborhood coloring', abbreviated CFON (CFCN) coloring, of a graph $G$ using $r$ colors is a coloring of the vertices of $G$ such that every vertex sees some color exactly once in its open (closed)…

Combinatorics · Mathematics 2021-12-24 Sriram Bhyravarapu , Subrahmanyam Kalyanasundaram , Rogers Mathew

Let G be a graph on n vertices with maximum degree D. We use the Lov\'asz local lemma to show the following two results about colourings c of the edges of the complete graph K_n. If for each vertex v of K_n the colouring c assigns each…

Combinatorics · Mathematics 2010-07-23 Julia Böttcher , Yoshiharu Kohayakawa , Aldo Procacci

A properly edge-colored graph is a graph with a coloring of its edges such that no vertex is incident to two or more edges of the same color. A subgraph is called rainbow if all its edges have different colors. The problem of finding…

Combinatorics · Mathematics 2024-12-19 Benny Sudakov

For a graph $G$ of order $n$ a maximal edge coloring is a proper edge coloring with $\chi'(K_n)$ colors such that adding any edge to $G$ in any color makes it improper. Meszka and Tyniec proved that for some values of the number of edges…

Combinatorics · Mathematics 2019-12-23 Sebastian Babiński , Andrzej Grzesik

The concept of rainbow disconnection number of graphs was introduced by Chartrand et al. in 2018. Inspired by this concept, we put forward the concepts of rainbow vertex-disconnection and proper disconnection in graphs. In this paper, we…

Combinatorics · Mathematics 2020-07-30 You Chen , Ping Li , Xueliang Li , Yindi Weng

A coloring of a graph is an assignment of colors to its vertices such that adjacent vertices have different colors. Two colorings are equivalent if they induce the same partition of the vertex set into color classes. Let $\mathcal{A}(G)$ be…

Combinatorics · Mathematics 2024-03-11 Alain Hertz , Hadrien Mélot , Sébastien Bonte , Gauvain Devillez , Pierre Hauweele

Let $G$ be an edge-colored graph. We use $e(G)$ and $c(G)$ to denote the number of edges and colors in $G$, respectively. A subgraph $H$ is called rainbow if $c(H)=e(H)$. Li et al. (European J. Combin., 36 (2014), 453-459) proved that every…

Combinatorics · Mathematics 2025-11-07 Hongliang Lu , Zixuan Yang , Feihong Yuan

Let $G(V,E)$ be a $k$-uniform hypergraph. A hyperedge $e \in E$ is said to be properly $(r,p)$ colored by an $r$-coloring of vertices in $V$ if $e$ contains vertices of at least $p$ distinct colors in the $r$-coloring. An $r$-coloring of…

Discrete Mathematics · Computer Science 2015-07-10 Tapas Kumar Mishra , Sudebkumar Prasant Pal

Given positive integers $k \leq m$ and a graph $G$, a family of lists $L = \{L(v) : v \in V(G)\}$ is said to be a random $(k,m)$-list-assignment if for every $v \in V(G)$ the list $L(v)$ is a subset of $\{1, \ldots, m\}$ of size $k$, chosen…

Combinatorics · Mathematics 2024-04-10 Dan Hefetz , Michael Krivelevich

Let $G$ be an edge-colored graph on $n$ vertices. The minimum color degree of $G$, denoted by $\delta^c(G)$, is defined as the minimum number of colors assigned to the edges incident to a vertex in $G$. In 2013, H. Li proved that an…

Combinatorics · Mathematics 2025-10-16 Xueliang Li , Bo Ning , Yongtang Shi , Shenggui Zhang

A $b$-coloring of a graph is a proper coloring such that every color class contains a vertex adjacent to at least one vertex in each of the other color classes. The $b$-chromatic number of a graph $G$, denoted by $b(G)$, is the maximum…

Combinatorics · Mathematics 2013-02-19 Amine El Sahili , Mekkia Kouider , Maidoun Mortada

A proper vertex colouring of a graph is \emph{nested} if the vertices of each of its colour classes can be ordered by inclusion of their open neighbourhoods. Through a relation to partially ordered sets, we show that the nested chromatic…

Combinatorics · Mathematics 2013-06-04 David Cook
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