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This paper studies two variants of defective acyclic coloring of planar graphs. For a graph $G$ and a coloring $\varphi$ of $G$, a 2CC transversal is a subset $E'$ of $E(G)$ that intersects every 2-colored cycle. Let $k$ be a positive…

Combinatorics · Mathematics 2023-01-30 On-Hei Solomon Lo , Ben Seamone , Xuding Zhu

Given a collection $\mathcal{G}=(G_1,\dots, G_h)$ of graphs on the same vertex set $V$ of size $n$, an $h$-edge graph $H$ on the vertex set $V$ is a $\mathcal{G}$-transversal if there exists a bijection $\lambda : E(H) \rightarrow [h]$ such…

Combinatorics · Mathematics 2023-02-21 Debsoumya Chakraborti , Seonghyuk Im , Jaehoon Kim , Hong Liu

An acyclic edge coloring of a graph is a proper edge coloring without any bichromatic cycles. The acyclic chromatic index of a graph $G$ denoted by $a'(G)$, is the minimum $k$ such that $G$ has an acyclic edge coloring with $k$ colors.…

Combinatorics · Mathematics 2024-01-31 Nevil Anto , Manu Basavaraju , Suresh Manjanath Hegde , Shashanka Kulamarva

A strong edge colouring of a graph is an assignment of colours to the edges of the graph such that for every colour, the set of edges that are given that colour form an induced matching in the graph. The strong chromatic index of a graph…

Combinatorics · Mathematics 2013-08-20 Manu Basavaraju , Mathew C. Francis

Assume $G$ is a graph. We view $G$ as a symmetric digraph, in which each edge $uv$ of $G$ is replaced by a pair of opposite arcs $e=(u,v)$ and $e^{-1}=(v,u)$. Assume $S$ is an inverse closed subset of permutations of positive integers. We…

Combinatorics · Mathematics 2019-08-07 Ligang Jin , Tsai-Lien Wong , Xuding Zhu

A graph $G$ is well-covered if it has no isolated vertices and all the maximal independent sets have the same cardinality. If furthermore two times this cardinality is equal to $|V(G)|$, the graph $G$ is called very well-covered. The class…

Commutative Algebra · Mathematics 2010-06-08 Mohammad Mahmoudi , Amir Mousivand , Marilena Crupi , Giancarlo Rinaldo , Naoki Terai , Siamak Yassemi

The reconfiguration graph of the $k$-colorings of a graph $G$, denoted $R_{k}(G)$, is the graph whose vertices are the $k$-colorings of $G$ and two colorings are adjacent in $R_{k}(G)$ if they differ in color on exactly one vertex. A graph…

Combinatorics · Mathematics 2026-02-19 Manoj Belavadi , Kathie Cameron , Ni Luh Dewi Sintiari

Odd coloring is a proper coloring with an additional restriction that every non-isolated vertex has some color that appears an odd number of times in its neighborhood. The minimum number of colors $k$ that can ensure an odd coloring of a…

Combinatorics · Mathematics 2022-06-14 Fangyu Tian , Yuxue Yin

Let $G$ be a graph on $n$ vertices and $t$ an integer. The reconfiguration graph of $G$, denoted by $R_t(G)$, consists of all $t$-colorings of $G$ and two $t$-colorings are adjacent if they differ on exactly one vertex. The $t$-recoloring…

Combinatorics · Mathematics 2025-11-05 Yichen Wang , Mei Lu

Given a graph $G$ and a mapping $f:V(G) \to \mathbb{N}$, an $f$-list assignment of $G$ is a function that maps each $v \in V(G)$ to a set of at least $f(v)$ colors. For an $f$-list assignment $L$ of a graph $G$, a proper conflict-free…

Combinatorics · Mathematics 2025-09-05 Masaki Kashima , Riste Škrekovski , Rongxing Xu

An edge coloring of a graph $G$ is to color all the edges in the graph such that adjacent edges receive different colors. It is acyclic if each cycle in the graph receives at least three colors. Fiam{\v{c}}ik (1978) and Alon, Sudakov and…

Discrete Mathematics · Computer Science 2023-06-29 Qiaojun Shu , Guohui Lin

A {\em hole} is a chordless cycle of length at least four. A hole is {\em even} (resp. {\em odd}) if it contains an even (resp. odd) number of vertices. A \emph{cap} is a graph induced by a hole with an additional vertex that is adjacent to…

Discrete Mathematics · Computer Science 2015-11-02 Shenwei Huang , Murilo V. G. da Silva

In this paper, we aim to introduce the group version of edge coloring and list edge coloring, and prove that all 2-degenerate graphs along with some planar graphs without adjacent short cycles is group $(\Delta(G)+1)$-edge-choosable while…

Combinatorics · Mathematics 2011-05-31 Xin Zhang , Guizhen Liu

DP-coloring of a simple graph is a generalization of list coloring, and also a generalization of signed coloring of signed graphs. It is known that for each $k \in \{3, 4, 5, 6\}$, every planar graph without $C_k$ is 4-choosable.…

Combinatorics · Mathematics 2017-09-29 Seog-Jin Kim , Kenta Ozeki

Let $G$ be a graph and let $C$ be a color set of cardinality $k$. Suppose $c \colon V(G) \to C$ is a (not necessarily proper) vertex coloring whose all color classes are $V_1$, $V_2$, $\dots$, $V_k$, each of which is nonempty. The vertex…

Combinatorics · Mathematics 2025-12-15 Saeed Shaebani

DP-coloring, also known as correspondence coloring, is introduced by Dvo{\v{r}}{\'{a}}k and Postle. It is a generalization of list coloring. In this paper, we show that every connected toroidal graph without triangles adjacent to $5$-cycles…

Combinatorics · Mathematics 2019-08-15 Tao Wang

Wang and Lih in 2002 conjectured that every planar graph without adjacent triangles is 4-choosable. In this paper, we prove that every planar graph without any 4-cycle adjacent to two triangles is DP-4-colorable, which improves the results…

Combinatorics · Mathematics 2018-04-25 Runrun Liu , Xiangwen Li

A proper conflict-free coloring of a graph is a proper vertex coloring wherein each non-isolated vertex's open neighborhood contains at least one color appearing exactly once. For a non-negative integer $k$, a graph $G$ is said to be proper…

Combinatorics · Mathematics 2025-12-30 Yuting Wang , Xin Zhang

DP-coloring (also known as correspondence coloring) is a generalization of list coloring introduced recently by Dvo\v{r}\'ak and Postle (2017). In this paper, we prove that every planar graph $G$ without $4$-cycles adjacent to $k$-cycles is…

Combinatorics · Mathematics 2018-11-08 Lily Chen , Runrun Liu , Gexin Yu , Ren Zhao , Xiangqian Zhou

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
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