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Based on the algorithmic proof of Lov\'asz local lemma due to Moser and Tardos, the works of Grytczuk et al. on words, and Dujmovi\'c et al. on colorings, Esperet and Parreau developed a framework to prove upper bounds for several chromatic…

Discrete Mathematics · Computer Science 2015-01-23 Daniel Gonçalves , Mickaël Montassier , Alexandre Pinlou

A {\em strong $k$-edge-coloring} of a graph $G$ is a mapping from $E(G)$ to $\{1,2,\ldots,k\}$ such that every two adjacent edges or two edges adjacent to the same edge receive distinct colors. The {\em strong chromatic index} $\chi_s'(G)$…

Combinatorics · Mathematics 2018-01-24 Ilkyoo Choi , Jaehoon Kim , Alexandr V. Kostochka , André Raspaud

A subgraph $H$ of a multigraph $G$ is overfull if $ |E(H) | > \Delta(G) \lfloor |V(H)|/2 \rfloor$. Analogous to the Overfull Conjecture proposed by Chetwynd and Hilton in 1986, Stiebitz et al. in 2012 formed the multigraph version of the…

Combinatorics · Mathematics 2023-07-13 Michael J. Plantholt , Songling Shan

Let $mad(G)$ denote the maximum average degree (over all subgraphs) of $G$ and let $\chi_i(G)$ denote the injective chromatic number of $G$. We prove that if $mad(G) \leq 5/2$, then $\chi_i(G)\leq\Delta(G) + 1$; and if $mad(G) < 42/19$,…

Combinatorics · Mathematics 2011-10-12 Daniel W. Cranston , Seog-Jin Kim , Gexin Yu

We prove that the acyclic chromatic number of a graph with maximum degree $\Delta$ is less than $2.835\Delta^{4/3}+\Delta$. This improves the previous upper bound, which was $50\Delta^{4/3}$. To do so, we draw inspiration from works by…

Combinatorics · Mathematics 2013-12-20 Jean-Sébastien Sereni , Jan Volec

Let $G$ be a simple graph on $n$ vertices and $m$ edges with chromatic number $\chi$, and let $\lambda_n$ denote the least adjacency eigenvalue. Solving a conjecture of Fan, Yu and Wang~[Electron. J. Combin., 2012], we prove that when $3\le…

Combinatorics · Mathematics 2026-01-22 Quanyu Tang , Clive Elphick

For a graph G and an integer t we let mcc_t(G) be the smallest m such that there exists a coloring of the vertices of G by t colors with no monochromatic connected subgraph having more than m vertices. Let F be any nontrivial minor-closed…

Combinatorics · Mathematics 2007-05-23 N. Linial , J. Matousek , O. Sheffet , G. Tardos

We show that for any fixed integer $m \geq 1$, a graph of maximum degree $\Delta$ has a coloring with $O(\Delta^{(m+1)/m})$ colors in which every connected bicolored subgraph contains at most $m$ edges. This result unifies previously known…

Combinatorics · Mathematics 2022-09-28 Peter Bradshaw

Suppose in a graph $G$ vertices can be either red or blue. Let $k$ be odd. At each time step, each vertex $v$ in $G$ polls $k$ random neighbours and takes the majority colour. If it doesn't have $k$ neighbours, it simply polls all of them,…

Distributed, Parallel, and Cluster Computing · Computer Science 2019-08-01 Mohammed Amin Abdullah , Moez Draief

The \textit{$r$-dynamic choosability} of a graph $G$, written ${\rm ch}_r(G)$, is the least $k$ such that whenever each vertex is assigned a list of at least $k$ colors a proper coloring can be chosen from the lists so that every vertex $v$…

Combinatorics · Mathematics 2018-01-24 Jaehoon Kim , Seongmin Ok

Let G be a triangle-free graph with maximum degree \delta(G). We show that the chromatic number \c{hi}(G) is less than 67(1 + o(1))\delta/ log \delta.

Combinatorics · Mathematics 2011-06-13 Mohammad Shoaib Jamall

Let $G$ be a graph of order $n$ and $P(G,x)$ be the chromatic polynomial of $G$. Dong, Ge, Gong, Ning, Ouyang, and Tay (J. Graph Theory 96(2021) 343) conjectured that $\frac{d^k}{dx^k} \bigl( \ln[(-1)^n P(G, x)] \bigr) < 0$ holds for all $k…

Combinatorics · Mathematics 2026-03-20 Yan Yang

Erd\H{o}s, Gallai, and Tuza posed the following problem: given an $n$-vertex graph $G$, let $\tau_1(G)$ denote the smallest size of a set of edges whose deletion makes $G$ triangle-free, and let $\alpha_1(G)$ denote the largest size of a…

Combinatorics · Mathematics 2015-03-26 Gregory J. Puleo

Let $\Delta(G)$ and $\chi'(G)$ be the maximum degree and chromatic index of a graph $G$, respectively. Appearing in different forms, Gupta\,(1967), Goldberg\,(1973), Andersen\,(1977), and Seymour\,(1979) made the following conjecture: Every…

Combinatorics · Mathematics 2026-02-18 Guangming Jing

Vizing's theorem asserts the existence of a $(\Delta+1)$-edge coloring for any graph $G$, where $\Delta = \Delta(G)$ denotes the maximum degree of $G$. Several polynomial time $(\Delta+1)$-edge coloring algorithms are known, and the…

Data Structures and Algorithms · Computer Science 2024-08-05 Sayan Bhattacharya , Martín Costa , Nadav Panski , Shay Solomon

We analyse uniformly random proper $k$-colourings of sparse graphs with maximum degree $\Delta$ in the regime $\Delta < k\ln k $. This regime corresponds to the lower side of the shattering threshold for random graph colouring, a…

Combinatorics · Mathematics 2023-03-28 Eoin Hurley , François Pirot

For a multigraph $G$, $\chi'(G)$ denotes the chromatic index of $G$, $\Delta(G)$ the maximum degree of $G$, and $\Gamma(G) = \max\left\{\left\lceil \frac{2|E(H)|}{|V(H)|-1} \right\rceil: H \subseteq G \text{ and } |V(H)| \text{…

Combinatorics · Mathematics 2024-07-15 Guantao Chen , Yanli Hao , Xingxing Yu , Wenan Zang

Vizing's theorem states that any $n$-vertex $m$-edge graph of maximum degree $\Delta$ can be edge colored using at most $\Delta + 1$ different colors. Vizing's original proof is easily translated into a deterministic $O(mn)$ time algorithm.…

Data Structures and Algorithms · Computer Science 2025-10-20 Sepehr Assadi , Soheil Behnezhad , Sayan Bhattacharya , Martín Costa , Shay Solomon , Tianyi Zhang

A well-known conjecture by Harris states that any triangle-free $d$-degenerate graph has fractional chromatic number at most $O\left(\frac{d}{\ln d}\right)$. This conjecture has gained much attention in recent years, and is known to have…

Combinatorics · Mathematics 2025-01-31 Anders Martinsson

A long-standing conjecture asserts that there exists a constant $c>0$ such that every graph of order $n$ without isolated vertices contains an induced subgraph of order at least $cn$ with all degrees odd. Scott (1992) proved that every…

Combinatorics · Mathematics 2017-07-18 Xinmin Hou , Lei Yu , Jiaao Li , Boyuan Liu