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In this paper, we consider a weighted generalization of the chromatic number of a Binomial random graph~\(G.\) We equip each edge with a random weight and then colour the vertices in such a way that the absolute colour difference between…

Combinatorics · Mathematics 2023-11-21 Ghurumuruhan Ganesan

A proper vertex-coloring of a graph is $r$-dynamic if the neighbors of each vertex $v$ receive at least $\min(r, \mathrm{deg}(v))$ different colors. In this note, we prove that if $G$ has a strong $2$-coloring number at most $k$, then $G$…

Combinatorics · Mathematics 2025-01-24 Miriam Goetze , Torsten Ueckerdt

Given integers $m\le c$ and an exact $c$-coloring of the edges of a complete countably infinite graph (i.e. a coloring that uses exactly $c$ colors), must there be an infinite subgraph that is exactly $m$-colored? Using the Infinite Ramsey…

Combinatorics · Mathematics 2025-12-05 Žarko Ranđelović

Recently, Borodin, Kostochka, and Yancey (On $1$-improper $2$-coloring of sparse graphs. Discrete Mathematics, 313(22), 2013) showed that the vertices of each planar graph of girth at least $7$ can be $2$-colored so that each color class…

Combinatorics · Mathematics 2015-07-13 Maria Axenovich , Torsten Ueckerdt , Pascal Weiner

The packing chromatic number of a graph is the minimum number of colors for which the graph admits a packing coloring. This distance-based parameter may change under local structural modifications of the graph. In this paper, we introduce…

Combinatorics · Mathematics 2026-05-20 Batoul Tarhini , Didem Gözüpek

An edge-coloring of a graph $G$ with colors $1,2,\ldots,t$ is an interval $t$-coloring if all colors are used, and the colors of edges incident to each vertex of $G$ are distinct and form an interval of integers. A graph $G$ is interval…

Discrete Mathematics · Computer Science 2016-04-01 Hrant H. Khachatrian , Petros A. Petrosyan

A proper coloring $c$ of a simple graph $G$ is harmonious if, for every pair of distinct edges $uv,xy\in E(G)$, we have that $\{c(u),c(v)\}\neq \{c(x),c(y)\}$. The harmonious chromatic number of $G$, denoted by $h(G)$, is the least positive…

Combinatorics · Mathematics 2026-05-19 Júlio Araújo , Manoel Campêlo , Beatriz Martins , Marcio C. Santos

We prove that for every $d\in \mathbb{N}$ and a graph class of bounded expansion $\mathscr{C}$, there exists some $c\in \mathbb{N}$ so that every graph from $\mathscr{C}$ admits a proper coloring with at most $c$ colors satisfying the…

Combinatorics · Mathematics 2025-05-22 Michał Pilipczuk

A well-studied coloring problem is to assign colors to the edges of a graph $G$ so that, for every pair of vertices, all edges of at least one shortest path between them receive different colors. The minimum number of colors necessary in…

Data Structures and Algorithms · Computer Science 2018-01-17 L. Sunil Chandran , Anita Das , Davis Issac , Erik Jan van Leeuwen

The acyclic chromatic index (or acyclic edge-chromatic number) of a graph is the least number of colors needed to properly color its edges so that none of its cycles has only two colors. We show that for a graph of max degree $\Delta$, the…

Combinatorics · Mathematics 2026-02-17 Lefteris Kirousis , John Livieratos , Alexandros Singh

The "clustered chromatic number" of a class of graphs is the minimum integer $k$ such that for some integer $c$ every graph in the class is $k$-colourable with monochromatic components of size at most $c$. We determine the clustered…

Combinatorics · Mathematics 2022-01-24 Sergey Norin , Alex Scott , David R. Wood

A star edge coloring of a graph $G$ is a proper edge coloring of $G$ such that every path and cycle of length four in $G$ uses at least three different colors. The star chromatic index of a graph $G$, is the smallest integer $k$ for which…

Combinatorics · Mathematics 2018-12-27 Behnaz Omoomi , Elham Roshanbin , Marzieh Vahid Dastjerdi

A proper $q$-coloring of a domain in $\mathbb{Z}^d$ is a function assigning one of $q$ colors to each vertex of the domain such that adjacent vertices are colored differently. Sampling a proper $q$-coloring uniformly at random, does the…

Probability · Mathematics 2020-07-29 Ron Peled , Yinon Spinka

A tree $T$ in an edge-colored graph is a \emph{proper tree} if any two adjacent edges of $T$ are colored with different colors. Let $G$ be a graph of order $n$ and $k$ be a fixed integer with $2\leq k\leq n$. For a vertex set $S\subseteq…

Combinatorics · Mathematics 2016-01-15 Lin Chen , Xueliang Li , Jinfeng Liu

The packing chromatic number $\chi_{\rho}(G)$ of a graph $G$ is the smallest integer $p$ such that vertices of $G$ can be partitioned into disjoint classes $X_{1}, ..., X_{p}$ where vertices in $X_{i}$ have pairwise distance greater than…

Combinatorics · Mathematics 2013-02-05 Jan Ekstein , Přemysl Holub , Olivier Togni

We prove that every triangle-free graph of tree-width t has chromatic number at most ceil((t + 3)/2), and demonstrate that this bound is tight. The argument also establishes a connection between coloring graphs of tree-width t and on-line…

Combinatorics · Mathematics 2017-06-12 Zdeněk Dvořák , Ken-ichi Kawarabayashi

Let $\chi'_d(n,q)$ (resp. $\chi_d(n,q)$) denote the minimum number of colors necessary to color a $q$-ary $n$-cube so that no two vertices that are at a distance at most $d$ (resp. exactly $d$) get the same color. These two problems were…

Combinatorics · Mathematics 2015-10-29 Z. Han , M. Lu

Fong et al. (The game chromatic index of some trees with maximum degree four and adjacent degree-four vertices, J. Comb Optim 36 (2018) 1-12) proved that the game chromatic index of any tree $T$ of maximum degree 4 whose degree-four…

Combinatorics · Mathematics 2019-04-03 Wai Lam Fong , Wai Hong Chan

We call a proper edge coloring of a graph $G$ a B-coloring if every 4-cycle of $G$ is colored with four different colors. Let $q_B(G)$ denote the smallest number of colors needed for a B-coloring of $G$. Motivated by earlier papers on…

Combinatorics · Mathematics 2025-09-03 András Gyárfás , Ryan R. Martin , Miklós Ruszinkó , Gábor N. Sárközy

For a graph $G$, the tree graph ${\cal T}_{G,t}$ has all tree subgraphs of $G$ with $t$ vertices as vertex set and two tree subgraphs are neighbors if they are edge-disjoint. Also, the $r^{th}$ cut number of $G$ is the minimum number of…

Combinatorics · Mathematics 2015-12-01 Meysam Alishahi , Hossein Hajiabolhassan