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DP-coloring (also known as correspondence coloring) is a generalization of list coloring developed recently by Dvorak and Postle. We introduce and study $(i,j)$-defective DP-colorings of multigraphs. We concentrate on sparse multigraphs and…

Combinatorics · Mathematics 2019-12-10 Yifan Jing , Alexandr Kostochka , Fuhong Ma , Pongpat Sittitrai , Jingwei Xu

DP-coloring (also known as correspondence coloring) is a generalization of list coloring developed recently by Dvo\v{r}\'ak and Postle. We introduce and study $(i,j)$-defective DP-colorings of simple graphs. Let $g_{DP}(i,j,n)$ be the…

Combinatorics · Mathematics 2020-06-19 Yifan Jing , Alexandr Kostochka , Fuhong Ma , Jingwei Xu

In Defective Coloring we are given a graph $G = (V, E)$ and two integers $\chi_d, \Delta^*$ and are asked if we can partition $V$ into $\chi_d$ color classes, so that each class induces a graph of maximum degree $\Delta^*$. We investigate…

Data Structures and Algorithms · Computer Science 2018-01-12 Rémy Belmonte , Michael Lampis , Valia Mitsou

A proper edge coloring of a graph $G$ with colors $1,2,\dots,t$ is called a cyclic interval $t$-coloring if for each vertex $v$ of $G$ the edges incident to $v$ are colored by consecutive colors, under the condition that color $1$ is…

Combinatorics · Mathematics 2017-11-15 Armen S. Asratian , Carl Johan Casselgren , Petros A. Petrosyan

Consider the following two ways to colour the vertices of a graph where the requirement that adjacent vertices get distinct colours is relaxed. A colouring has "defect" $d$ if each monochromatic component has maximum degree at most $d$. A…

Combinatorics · Mathematics 2018-03-22 David R. Wood

DP-coloring is a generalization of a list coloring in simple graphs. Many results in list coloring can be generalized in those of DP-coloring. Kim and Ozeki showed that planar graphs without $k$-cycles where $k=3,4,5,$ or $6$ are…

Combinatorics · Mathematics 2018-02-01 Pongpat Sittitrai , Kittikorn Nakprasit

A \textit{star $k$-coloring} of a graph $G$ is a proper (vertex) $k$-coloring of $G$ such that the vertices on a path of length three receive at least three colors. Given a graph $G$, its \textit{star chromatic number}, denoted $\chi_s(G)$,…

Combinatorics · Mathematics 2019-09-26 Ilkyoo Choi , Boram Park

Graph coloring with preferences offers a powerful framework for constraint satisfaction problems in which fulfilling every request is impossible but satisfying a guaranteed positive fraction is highly desirable. A \emph{request} on a graph…

Combinatorics · Mathematics 2026-05-25 Shu Fang , Runrun Liu , Gexin Yu

Two (proper) colorings of a graph are adjacent if they differ on exactly one vertex. Jerrum proved that any $(d + 2)$-coloring of any d-degenerate graph can be transformed into any other via a sequence of adjacent colorings. A result of…

Discrete Mathematics · Computer Science 2020-12-22 Valentin Bartier , Nicolas Bousquet , Marc Heinrich

A strong edge-coloring of a graph $G$ is an edge-coloring such that any two edges on a path of length three receive distinct colors. We denote the strong chromatic index by $\chi_{s}'(G)$ which is the minimum number of colors that allow a…

Combinatorics · Mathematics 2018-01-23 Baochen Zhang , Yulin Chang , Jie Hu , Meijie Ma , Donglei Yang

A graph is 2-degenerate if every subgraph contains a vertex of degree at most 2. We show that every 2-degenerate graph can be drawn with straight lines such that the drawing decomposes into 4 plane forests. Therefore, the geometric…

Combinatorics · Mathematics 2023-03-01 Rahul Jain , Marco Ricci , Jonathan Rollin , André Schulz

The \emph{slow-coloring game} is played by Lister and Painter on a graph $G$. Initially, all vertices of $G$ are uncolored. In each round, Lister marks a nonempty set $M$ of uncolored vertices, and Painter colors a subset of $M$ that is…

The domatic number of a graph $G$ is the maximum number of pairwise disjoint dominating sets of $G$. We are interested in the LP-relaxation of this parameter, which is called the fractional domatic number of $G$. We study its extremal value…

Combinatorics · Mathematics 2025-08-28 Quentin Chuet , Hugo Demaret , Hoang La , François Pirot

Assume $L$ is a $k$-list assignment of a graph $G$. A $d$-defective $m$-fold $L$-colouring $\phi$ of $G$ assigns to each vertex $v$ a set $\phi(v)$ of $m$ colours, so that $\phi(v) \subseteq L(v)$ for each vertex $v$, and for each colour…

Combinatorics · Mathematics 2016-05-17 Ming Han , Xuding Zhu

We define a weakly threshold sequence to be a degree sequence $d=(d_1,\dots,d_n)$ of a graph having the property that $\sum_{i \leq k} d_i \geq k(k-1)+\sum_{i > k} \min\{k,d_i\} - 1$ for all positive $k \leq \max\{i:d_i \geq i-1\}$. The…

Combinatorics · Mathematics 2023-06-22 Michael D. Barrus

Let $\mathscr{G}$ be the class of plane graphs without triangles normally adjacent to $8^{-}$-cycles, without $4$-cycles normally adjacent to $6^{-}$-cycles, and without normally adjacent $5$-cycles. In this paper, it is shown that every…

Combinatorics · Mathematics 2022-06-13 Fangyao Lu , Mengjiao Rao , Qianqian Wang , Tao Wang

A graph H is common if the number of monochromatic copies of H in a 2-edge-coloring of the complete graph is asymptotically minimized by the random coloring. The classification of common graphs is one of the most intriguing problems in…

Combinatorics · Mathematics 2022-04-28 Robert Hancock , Daniel Kral , Matjaz Krnc , Jan Volec

A dynamic coloring of a graph $G$ is a proper coloring such that for every vertex $v\in V(G)$ of degree at least 2, the neighbors of $v$ receive at least 2 colors. It was conjectured [B. Montgomery. {\em Dynamic coloring of graphs}. PhD…

Combinatorics · Mathematics 2011-10-25 Meysam Alishahi

A linear forest is a union of vertex-disjoint paths, and the linear arboricity of a graph $G$, denoted by $\operatorname{la}(G)$, is the minimum number of linear forests needed to partition the edge set of $G$. Clearly,…

Combinatorics · Mathematics 2023-10-03 Guantao Chen , Yanli Hao , Guoning Yu

Let $c\geq 2$ and $p\geq c$ be two integers. We will call a proper coloring of the graph $G$ a \textit{$(c,p)$-nondegenerate}, if for any vertex of $G$ with degree at least $p$ there are at least $c$ vertices of different colors adjacent to…

Combinatorics · Mathematics 2012-06-20 Nikolay Gravin