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We examine maximum vertex coloring of random geometric graphs, in an arbitrary but fixed dimension, with a constant number of colors. Since this problem is neither scale-invariant nor smooth, the usual methodology to obtain limit laws…

Probability · Mathematics 2016-11-17 Sem Borst , Milan Bradonjić

A {\bf $\mathbf{k}$-majority coloring} of a digraph $D=(V,A)$ is a coloring of $V$ with $k$ colors so that each vertex $v\in V$ has at least as many out-neighbours of color different from its own color as it has out-neighbours with the same…

Combinatorics · Mathematics 2025-08-27 Jørgen Bang-Jensen , Francois Pirot , Anders Yeo

For graphs $G$ and $H$, an {\em $H$-colouring} of $G$ (or {\em homomorphism} from $G$ to $H$) is a function from the vertices of $G$ to the vertices of $H$ that preserves adjacency. $H$-colourings generalize such graph theory notions as…

Combinatorics · Mathematics 2012-06-15 John Engbers , David Galvin

The classical theorem of Vizing states that every graph of maximum degree $d$ admits an edge-coloring with at most $d+1$ colors. Furthermore, as it was earlier shown by K\H{o}nig, $d$ colors suffice if the graph is bipartite. We investigate…

Combinatorics · Mathematics 2016-08-23 Endre Csóka , Gabor Lippner , Oleg Pikhurko

We show that there is a constant $C$ such that for every $\varepsilon>0$ any $2$-coloured $K_n$ with minimum degree at least $n/4+\varepsilon n$ in both colours contains a complete subgraph on $2t$ vertices where one colour class forms a…

Combinatorics · Mathematics 2022-11-04 António Girão , David Munhá Correia

The Unfriendly Partition Conjecture posits that every countable graph admits a 2-colouring in which for each vertex there are at least as many bichromatic edges containing that vertex as monochromatic ones. This is not known in general, but…

Combinatorics · Mathematics 2023-03-22 John Haslegrave

Alon, Krivelevich, and Sudakov conjectured in 1999 that every $F$-free graph of maximum degree at most $\Delta$ has chromatic number $O(\Delta / \log \Delta)$. This was previously known only for almost bipartite graphs, that is, for…

Combinatorics · Mathematics 2025-12-05 Abhishek Dhawan , Oliver Janzer , Abhishek Methuku

An $r$-hued coloring of a simple graph $G$ is a proper coloring of its vertices such that every vertex $v$ is adjacent to at least $\min\{r, \deg(v)\}$ differently colored vertices. The minimum number of colors needed for an $r$-hued…

Combinatorics · Mathematics 2022-11-03 Stanislav Jendroľ , Alfréd Onderko

We give a sharp refinement of a result of Alon, Ben-Shimon and Krivelevich. This gives a sufficient condition for a finite sequence of positive integers to be the vertex degree list of both parts of a bipartite graph. The condition depends…

Combinatorics · Mathematics 2014-03-26 Grant Cairns , Stacey Mendan , Yuri Nikolayevsky

A coloring of vertices of a graph is called perfect if, for every vertex, the collection of colors of its neighbors depends only on its own color. The correspondent color partition of vertices is called equitable. We note that a number of…

Combinatorics · Mathematics 2025-05-16 Vladimir N. Potapov

The reconfiguration graph $\mathcal{C}_k(G)$ for the $k$-colourings of a graph $G$ has a vertex for each proper $k$-colouring of $G$, and two vertices of $\mathcal{C}_k(G)$ are adjacent precisely when those $k$-colourings differ on a single…

Combinatorics · Mathematics 2023-10-03 Stijn Cambie , Wouter Cames van Batenburg , Daniel W. Cranston

The conflict-free chromatic index of a graph $G$ is the minimum number of colours in an edge colouring of $G$ such that the neighbourhood of every edge contains a colour appearing exactly once. Its vertex analogue is the conflict-free…

Combinatorics · Mathematics 2026-04-27 Mateusz Kamyczura , Jakub Przybyło

A proper vertex coloring of a simple graph is $k$-forested if the graph induced by the vertices of any two color classes is a forest with maximum degree less than $k$. A graph is $k$-forested $q$-choosable if for a given list of $q$ colors…

Combinatorics · Mathematics 2011-02-22 Xin Zhang , Guizhen Liu , Jian-Liang Wu

The acyclic chromatic number of a graph is the least number of colors needed to properly color its vertices so that none of its cycles has only two colors. We show that for all $\alpha>2^{-1/3}$ there exists an integer $\Delta_{\alpha}$…

Combinatorics · Mathematics 2022-05-24 Lefteris Kirousis , John Livieratos

We consider the problem of sampling a proper $k$-coloring of a graph of maximal degree $\Delta$ uniformly at random. We describe a new Markov chain for sampling colorings, and show that it mixes rapidly on graphs of bounded treewidth if…

Data Structures and Algorithms · Computer Science 2017-08-10 Shai Vardi

Vizing's theorem guarantees that every graph with maximum degree $\Delta$ admits an edge coloring using $\Delta + 1$ colors. In online settings - where edges arrive one at a time and must be colored immediately - a simple greedy algorithm…

Data Structures and Algorithms · Computer Science 2025-07-30 Joakim Blikstad , Ola Svensson , Radu Vintan , David Wajc

Recently, Milani\v{c} and Trotignon introduced the class of equistarable graphs as graphs without isolated vertices admitting positive weights on the edges such that a subset of edges is of total weight $1$ if and only if it forms a maximal…

Combinatorics · Mathematics 2015-02-24 Endre Boros , Nina Chiarelli , Martin Milanič

Given a proper edge coloring $\varphi$ of a graph $G$, we define the palette $S_{G}(v,\varphi)$ of a vertex $v \in V(G)$ as the set of all colors appearing on edges incident with $v$. The palette index $\check s(G)$ of $G$ is the minimum…

Combinatorics · Mathematics 2023-06-22 C. J. Casselgren , Petros A. Petrosyan

We determine the colored patterns that appear in any $2$-edge coloring of $K_{n,n}$, with $n$ large enough and with sufficient edges in each color. We prove the existence of a positive integer $z_2$ such that any $2$-edge coloring of…

Combinatorics · Mathematics 2024-07-15 Adriana Hansberg , Denae Ventura

In this paper we prove an asymptotic multipartite version of a well-known theorem of K\"uhn and Osthus by establishing, for any graph $H$ with chromatic number $r$, the asymptotic multipartite minimum degree threshold which ensures that a…

Combinatorics · Mathematics 2017-07-17 Ryan R. Martin , Richard Mycroft , Jozef Skokan
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