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Related papers: A survey of $\chi$-boundedness

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The clique chromatic number of a graph is the smallest number of colors in a vertex coloring so that no maximal clique is monochromatic. In 2016 McDiarmid, Mitsche and Pralat noted that around p \approx n^{-1/2} the clique chromatic number…

Combinatorics · Mathematics 2023-05-30 Lyuben Lichev , Dieter Mitsche , Lutz Warnke

If $\Gamma$ is a graph for which every edge is in exactly one clique of order $\omega$, then one can form a new graph with vertex set equal to these cliques. This is a generalization of the line graph of $\Gamma$. We discover many general…

Combinatorics · Mathematics 2025-02-26 Robert R. Petro , Connor M. Phillips

We investigate the notion of quantum chromatic number of a graph, which is the minimal number of colours necessary in a protocol in which two separated provers can convince an interrogator with certainty that they have a colouring of the…

Quantum Physics · Physics 2011-11-09 Peter J. Cameron , Ashley Montanaro , Michael W. Newman , Simone Severini , Andreas Winter

We systematically determine circular chromatic index of small graphs and multigraphs with maximum degree $4$, $5$, $6$ (and also their number for a given small order). We construct several infinite families of such graphs with circular…

Combinatorics · Mathematics 2026-03-11 Ján Mazák , Filip Zrubák

For $k\ge 1$, we consider interleaved $k$-tuple colorings of the nodes of a graph, that is, assignments of $k$ distinct natural numbers to each node in such a way that nodes that are connected by an edge receive numbers that are strictly…

Combinatorics · Mathematics 2013-02-13 V. C. Barbosa

Investigating the equality of the chromatic number and the circular chromatic number of graphs has been an active stream of research for last decades. In this regard, Habolhassan and Zhu [Circular chromatic number of Kneser graphs, Journal…

Combinatorics · Mathematics 2016-12-23 Meysam Alishahi , Ali Taherkhani

The {\em chromatic gap} is the difference between the chromatic number and the clique number of a graph. Here we investigate $\gap(n)$, the maximum chromatic gap over graphs on $n$ vertices. Can the extremal graphs be explored? While…

Combinatorics · Mathematics 2020-12-01 András Gyárfás , András Sebõ , Nicolas Trotignon

Recently, Balogh, Kostochka and Liu in [Packing chromatic number of cubic graphs, Discrete Math.~341 (2018) 474--483] answered in negative the question that was posed in several earlier papers whether the packing chromatic number is bounded…

Combinatorics · Mathematics 2018-01-31 Boštjan Brešar , Jasmina Ferme

We characterise the structure of those graphs of a given order which maximise the number of connected induced subgraphs for seven different graph classes, each with other prescribed parameters like minimum degree, independence number,…

Combinatorics · Mathematics 2023-03-06 Audace A. V. Dossou-Olory

We prove that a hereditary class of graphs is $(\mathsf{tw}, \omega)$-bounded if and only if the induced minors of the graphs from the class form a $(\mathsf{tw}, \omega)$-bounded class.

Combinatorics · Mathematics 2024-10-24 Claire Hilaire , Martin Milanič , Nicolas Trotignon , Djordje Vasić

Given a graph $G$ possibly with multiple edges but no loops, denote by $\Delta$ the {\it maximum degree}, $\mu$ the {\it multiplicity}, $\chi'$ the {\it chromatic index} and $\chi_f'$ the {\it fractional chromatic index} of $G$,…

Combinatorics · Mathematics 2016-12-13 Guantao Chen , Yuping Gao , Ringi Kim , Luke Postle , Songling Shan

For a simple graph $G$, let $\chi_f(G)$ be the fractional chromatic number of $G$. In this paper, we aim to establish upper bounds on $\chi_f(G)$ for those graphs $G$ with restrictions on the clique number. Namely, we prove that for $\Delta…

Combinatorics · Mathematics 2021-08-04 Xiaolan Hu , Xing Peng

Motivated by the definition of linear coloring on simplicial complexes, recently introduced in the context of algebraic topology \cite{Civan}, and the framework through which it was studied, we introduce the linear coloring on graphs. We…

Discrete Mathematics · Computer Science 2008-07-29 Kyriaki Ioannidou , Stavros D. Nikolopoulos

Let G be an n-vertex graph with list-chromatic number $\chi_\ell$. Suppose each vertex of G is assigned a list of t colors. Albertson, Grossman, and Haas conjecture that at least $t n / {\chi_\ell}$ vertices can be colored from these lists.…

Combinatorics · Mathematics 2007-05-23 Glenn G. Chappell

The proper conflict-free chromatic number, $\chi_{pcf}(G)$, of a graph $G$ is the least $k$ such that $G$ has a proper $k$-coloring in which for each non-isolated vertex there is a color appearing exactly once among its neighbors. The…

We discuss the minimal number of vertices in a graph with a large chromatic number such that each ball of a fixed radius in it has a small chromatic number. It is shown that for every graph $G$ on $\sim((n+rc)/(c+rc))^{r+1}$ vertices such…

Combinatorics · Mathematics 2014-02-03 Ilya I. Bogdanov

Given a graphic degree sequence $D$, let $\chi(D)$ (respectively $\omega(D)$, $h(D)$, and $H(D)$) denote the maximum value of the chromatic number (respectively, the size of the largest clique, largest clique subdivision, and largest clique…

Combinatorics · Mathematics 2009-07-10 Zdenek Dvorak , Bojan Mohar

A coloring of edges of a graph $G$ is injective if for any two distinct edges $e_1$ and $e_2$, the colors of $e_1$ and $e_2$ are distinct if they are at distance $1$ in $G$ or in a common triangle. Naturally, the injective chromatic index…

Combinatorics · Mathematics 2021-04-26 Alexandr Kostochka , André Raspaud , Jingwei Xu

After $2$-crossing-critical graphs were characterized in 2016, their most general subfamily, large $3$-connected $2$-crossing-critical graphs, has attracted separate attention. This paper presents sharp upper and lower bounds for their…

Combinatorics · Mathematics 2022-03-24 Vesna Iršič , Maruša Lekše , Mihael Pačnik , Petra Podlogar , Martin Praček

Given a graph $G$, the strong clique number $\omega_2'(G)$ of $G$ is the cardinality of a largest collection of edges every pair of which are incident or connected by an edge in $G$. We study the strong clique number of graphs missing some…

Combinatorics · Mathematics 2019-03-15 Wouter Cames van Batenburg , Ross J. Kang , François Pirot