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A proper coloring of a graph is \emph{conflict-free} if, for every non-isolated vertex, some color is used exactly once on its neighborhood. Caro, Petru\v{s}evski, and \v{S}krekovski proved that every graph $G$ has a proper conflict-free…

Combinatorics · Mathematics 2024-12-16 Daniel W. Cranston , Chun-Hung Liu

We define a $P$-compelling coloring as a proper coloring of the vertices of a graph such that every subset consisting of one vertex of each color has property $P$. The $P$-compelling chromatic number is the minimum number of colors in such…

Combinatorics · Mathematics 2021-05-11 Anna Bachstein , Wayne Goddard , Michael A. Henning , John Xue

An incidence of a graph $G$ is a pair $(u,e)$ where $u$ is a vertex of $G$ and $e$ is an edge of $G$ incident with $u$. Two incidences $(u,e)$ and $(v,f)$ of $G$ are adjacent whenever (i) $u=v$, or (ii) $e=f$, or (iii) $uv=e$ or $uv=f$. An…

Combinatorics · Mathematics 2018-04-18 Sungsik Kang , Boram Park

In this paper, a $k$-edge-coloring of $G$ is any mapping $c:E(G)\longrightarrow [k]$. The edge-coloring $c$ of $G$ naturally defines a vertex-coloring $\sigma_{c}: V(G) \to \mathbb{N}$, where $\sigma_{c}(v)=\sum_{u\in N_G(v)}c(vu)$ for…

Combinatorics · Mathematics 2025-11-04 Rafał Kalinowski , Monika Pilśniak , Elżbieta Sidorowicz , Elżbieta Turowska

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

A graph is called $k$-critical if its chromatic number is $k$ but any proper subgraph has chromatic number less than $k$. An old and important problem in graph theory asks to determine the maximum number of edges in an $n$-vertex…

Combinatorics · Mathematics 2023-01-05 Cong Luo , Jie Ma , Tianchi Yang

We consider the so-called coupon-coloring of the vertices of a graph where every color appears in every open neighborhood, and our aim is to determine the maximal number of colors in such colorings. In other words, every color class must be…

Combinatorics · Mathematics 2017-08-08 Zoltán Lóránt Nagy

Let G=(V,E) be a graph and let f be a function that assigns list sizes to the vertices of G. It is said that G is f-choosable if for every assignment of lists of colors to the vertices of G for which the list sizes agree with f, there…

Combinatorics · Mathematics 2013-05-10 Michelle Lastrina , Michael Young

An equitable coloring is a proper coloring of a graph such that the sizes of the color classes differ by at most one. A graph $G$ is equitably $k$-colorable if there exists an equitable coloring of $G$ which uses $k$ colors, each one…

Combinatorics · Mathematics 2018-03-21 Hemanshu Kaul , Jeffrey A. Mudrock , Michael J. Pelsmajer

We say that a graph is $k$-mixing if it is possible to transform any $k$-coloring into any other via a sequence of single vertex recolorings keeping a proper coloring all along. Cereceda, van den Heuvel and Johnson proved that deciding if a…

Combinatorics · Mathematics 2024-01-09 Nicolas Bousquet

It is known that every loopless cubic graph is 4-edge choosable. We prove the following strengthened result. Let G be a planar cubic graph having b cut-edges. There exists a set F of at most 5b/2 edges of G with the following property. For…

Combinatorics · Mathematics 2012-10-31 Luis Goddyn , Andrea Spencer

In the List $k$-Coloring problem we are given a graph whose every vertex is equipped with a list, which is a subset of $\{1,\ldots,k\}$. We need to decide if $G$ admits a proper coloring, where every vertex receives a color from its list.…

Combinatorics · Mathematics 2025-09-29 Marta Piecyk , Paweł Rzążewski

A coloring of a graph is an assignment of colors to its vertices such that adjacent vertices have different colors. Two colorings are equivalent if they induce the same partition of the vertex set into color classes. Let $\mathcal{A}(G)$ be…

Combinatorics · Mathematics 2024-03-11 Alain Hertz , Hadrien Mélot , Sébastien Bonte , Gauvain Devillez , Pierre Hauweele

Weak diameter coloring of graphs recently attracted attention partially due to its connection to asymptotic dimension of metric spaces. We consider weak diameter list-coloring of graphs in this paper. Dvo\v{r}\'{a}k and Norin proved that…

Combinatorics · Mathematics 2025-05-01 Joshua Crouch , Chun-Hung Liu

A $k$-coloring of a graph $G$ is a $k$-partition $\Pi=\{S_1,\ldots,S_k\}$ of $V(G)$ into independent sets, called \emph{colors}. A $k$-coloring is called \emph{neighbor-locating} if for every pair of vertices $u,v$ belonging to the same…

Combinatorics · Mathematics 2018-07-02 Liliana Alcon , Marisa Gutierrez , Carmen Hernando , Merce Mora , Ignacio M. Pelayo

A proper coloring $\phi$ of $G$ is called a proper conflict-free coloring of $G$ if for every non-isolated vertex $v$ of $G$, there is a color $c$ such that $|\phi^{-1}(c)\cap N_G(v)|=1$. As an analogy to degree-choosability of graphs, the…

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

Consider a graph whose vertices are colored in one of two colors, say black or white. A white vertex is called integrated if it has at least as many black neighbors as white neighbors, and similarly for a black vertex. The coloring as a…

Combinatorics · Mathematics 2025-06-10 Charles Burnette , Broden Caton , Olivia Coward , Julian Davis , Austin Teter

We consider three extremal problems about the number of copies of a fixed graph in another larger graph. First, we correct an error in a result of Reiher and Wagner and prove that the number of $k$-edge stars in a graph with density $x \in…

Combinatorics · Mathematics 2024-03-19 Emily Cairncross , Dhruv Mubayi

A "dominating $K_t$-model" in a graph $G$ is a sequence $(T_1,\dots,T_t)$ of pairwise vertex-disjoint connected subgraphs of $G$, such that whenever $1\leq i<j\leq t$ every vertex in $T_j$ has a neighbour in $T_i$. Replacing "every vertex…

An edge colouring of a graph is called distinguishing if there is no non-trivial automorphism which preserves it. We prove that every at most countable, finite or infinite, connected regular graph of order at least $7$ admits a…

Combinatorics · Mathematics 2025-02-25 Jakub Kwaśny , Marcin Stawiski