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A graph is said to be interval colourable if it admits a proper edge-colouring using palette $\mathbb{N}$ in which the set of colours incident to each vertex is an interval. The interval colouring thickness of a graph $G$ is the minimum $k$…

Hadwiger's conjecture asserts that every graph without a $K_t$-minor is $(t-1)$-colorable. It is known that the exact version of Hadwiger's conjecture does not extend to list coloring, but it has been conjectured by Kawarabayashi and Mohar…

Combinatorics · Mathematics 2021-10-19 Raphael Steiner

A vertex coloring of a graph is nonrepetitive if there is no path in the graph whose first half receives the same sequence of colors as the second half. While every tree can be nonrepetitively colored with a bounded number of colors (4…

Combinatorics · Mathematics 2021-12-23 Adam Gągol , Gwenaël Joret , Jakub Kozik , Piotr Micek

Given a graph $H$, let $g(n,H)$ denote the smallest $k$ for which the following holds. We can assign a $k$-colouring $f_v$ of the edge set of $K_n$ to each vertex $v$ in $K_n$ with the property that for any copy $T$ of $H$ in $K_n$, there…

Combinatorics · Mathematics 2023-04-25 Barnabás Janzer , Oliver Janzer

We consider coloring problems inspired by the theory of anti-Ramsey / rainbow colorings that we generalize to a far extent. Let $\mathcal{F}$ be a hereditary family of graphs; i.e., if $H\in \mathcal{F}$ and $H'\subset H$ then also…

Combinatorics · Mathematics 2024-12-17 Yair Caro , Zsolt Tuza

A graph G is (d_1,..,d_l)-colorable if the vertex set of G can be partitioned into subsets V_1,..,V_l such that the graph G[V_i] induced by the vertices of V_i has maximum degree at most d_i for all 1 <= i <= l. In this paper, we focus on…

Combinatorics · Mathematics 2013-06-06 Mickael Montassier , Pascal Ochem

A graph \( G \) is said to be (vertex) non-repetitively colored if no simple path in \( G \) has a sequence of vertex colors that forms a repetition. Formally, a coloring \( c: V(G) \to \{1, 2, \dots, k\} \) is non-repetitive if, for every…

Combinatorics · Mathematics 2025-10-14 Tianyi Tao , Junchi Zhang , Wentao Zhang , Alex Toole

The celebrated theorem of Robertson and Seymour states that in the family of minor-closed graph classes, there is a unique minimal class of graphs of unbounded tree-width, namely, the class of planar graphs. In the case of tree-width, the…

Combinatorics · Mathematics 2017-02-01 A. Collins , J. Foniok , N. Korpelainen , V. Lozin , V. Zamaraev

Limits of graphs were initiated recently in the two extreme contexts of dense and bounded degree graphs. This led to elegant limiting structures called graphons and graphings. These approach have been unified and generalized by authors in a…

Combinatorics · Mathematics 2013-12-03 Jaroslav Nesetril , Patrice Ossona De Mendez

Connections between structural graph theory and finite model theory recently gained a lot of attention. In this setting, many interesting questions remain on the properties of dependent (NIP) hereditary classes of graphs, in particular…

Combinatorics · Mathematics 2026-01-01 Hector Buffière , Patrice Ossona de Mendez

For a graph $G$, we call an edge coloring of $G$ an \textit{improper} \textit{interval edge coloring} if for every $v\in V(G)$ the colors, which are integers, of the edges incident with $v$ form an integral interval. The \textit{interval…

Combinatorics · Mathematics 2024-08-09 Seunghun Lee

We describe several graphs with arbitrarily large rankwidth (or equivalently with arbitrarily large cliquewidth). Korpelainen, Lozin, and Mayhill [Split permutation graphs, Graphs and Combinatorics, 30(3):633-646, 2014] proved that there…

Discrete Mathematics · Computer Science 2023-10-23 Chính Hoàng , Nicolas Trotignon

A graph $G$ is said to have \textit{bandwidth} at most $b$, if there exists a labeling of the vertices by $1,2,..., n$, so that $|i - j| \leq b$ whenever $\{i,j\}$ is an edge of $G$. Recently, B\"{o}ttcher, Schacht, and Taraz verified a…

Combinatorics · Mathematics 2015-03-17 Hao Huang , Choongbum Lee , Benny Sudakov

Let $G$ be a graph, $r \geq t$ integers, and $N \subseteq E(G)$. An $(r,t)$-threshold-coloring of $G$ with respect to $N$ is a mapping $c: V(G) \rightarrow \{0,\ldots,r-1\}$ such that $|c(u)-c(v)| \leq t$ for every $uv \in N$ and…

Combinatorics · Mathematics 2016-08-09 Gasper Fijavz , Matthias Kriesell

A $(a,b)$-coloring of a graph $G$ associates to each vertex a $b$-subset of a set of $a$ colors in such a way that the color-sets of adjacent vertices are disjoint. We define general reduction tools for $(a,b)$-coloring of graphs for $2\le…

Combinatorics · Mathematics 2023-10-06 Jean-Christophe Godin , Olivier Togni

A \emph{mixed interval graph} is an interval graph that has, for every pair of intersecting intervals, either an arc (directed arbitrarily) or an (undirected) edge. We are particularly interested in scenarios where edges and arcs are…

Discrete Mathematics · Computer Science 2024-08-09 Grzegorz Gutowski , Konstanty Junosza-Szaniawski , Felix Klesen , Paweł Rzążewski , Alexander Wolff , Johannes Zink

Treewidth is an important graph invariant, relevant for both structural and algorithmic reasons. A necessary condition for a graph class to have bounded treewidth is the absence of large cliques. We study graph classes closed under taking…

Combinatorics · Mathematics 2021-11-09 Clément Dallard , Martin Milanič , Kenny Štorgel

A (minimal) transversal of a partition is a set which contains exactly one element from each member of the partition and nothing else. A coloring of a graph is a partition of its vertex set into anticliques, that is, sets of pairwise…

Combinatorics · Mathematics 2022-11-30 Matthias Kriesell , Samuel Mohr

A class of graphs is $\chi$-bounded if there exists a function $f:\mathbb N\rightarrow \mathbb N$ such that for every graph $G$ in the class and an induced subgraph $H$ of $G$, if $H$ has no clique of size $q+1$, then the chromatic number…

Combinatorics · Mathematics 2019-01-16 Hojin Choi , O-joung Kwon , Sang-il Oum , Paul Wollan

Let $G$ be a plane graph with outer cycle $C$ and let $(L(v):v\in V(G))$ be a family of sets such that $|L(v)|\ge 5$ for every $v\in V(G)$. By an $L$-coloring of a subgraph $J$ of $G$ we mean a (proper) coloring $\phi$ of $J$ such that…

Combinatorics · Mathematics 2017-03-28 Luke Postle , Robin Thomas