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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

For a positive integer $k$, a $k$-colouring of a graph $G=(V,E)$ is a mapping $c: V\rightarrow\{1,2,...,k\}$ such that $c(u)\neq c(v)$ whenever $uv\in E$. The Colouring problem is to decide, for a given $G$ and $k$, whether a $k$-colouring…

Computational Complexity · Computer Science 2016-02-16 Petr A. Golovach , Matthew Johnson , Daniël Paulusma , Jian Song

Using the algebraic approach to promise constraint satisfaction problems, we establish complexity classifications of three natural variants of hypergraph colourings: standard nonmonochromatic colourings, conflict-free colourings, and…

Discrete Mathematics · Computer Science 2026-05-01 Tamio-Vesa Nakajima , Zephyr Verwimp , Marcin Wrochna , Stanislav Živný

A {\it proper conflict-free $c$-coloring} of a graph is a proper $c$-coloring such that each non-isolated vertex has a color appearing exactly once on its neighborhood. This notion was formally introduced by Fabrici et al., who proved that…

Combinatorics · Mathematics 2022-04-13 Eun-Kyung Cho , Ilkyoo Choi , Hyemin Kwon , Boram Park

We consider the k-strong conflict-free coloring of a set of points on a line with respect to a family of intervals: Each point on the line must be assigned a color so that the coloring has to be conflict-free, in the sense that in every…

Data Structures and Algorithms · Computer Science 2015-03-20 Luisa Gargano , Adele A. Rescigno

In this paper, we study the conflict-free coloring of graphs induced by neighborhoods. A coloring of a graph is conflict-free if every vertex has a uniquely colored vertex in its neighborhood. The conflict-free coloring problem is to color…

Data Structures and Algorithms · Computer Science 2017-10-03 I. Vinod Reddy

Let $G$ be a graph with maximum degree $\Delta$ and without isolated vertices. An edge colouring $c$ of $G$ is conflict-free if the closed neighbourhood of every edge includes a uniquely coloured element. The least number of colours…

Combinatorics · Mathematics 2022-03-07 Mateusz Kamyczura , Mariusz Meszka , Jakub Przybyło

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 of degree-choosability of graphs, we…

Combinatorics · Mathematics 2025-09-22 Masaki Kashima , Riste Škrekovski , Rongxing Xu

An edge-colored graph $G$ is conflict-free connected if any two of its vertices are connected by a path, which contains a color used on exactly one of its edges. The conflict-free connection number of a connected graph $G$, denoted by…

Combinatorics · Mathematics 2020-12-10 Jing Wang , Meng Ji

A proper conflict-free colouring of a graph is a colouring of the vertices such that any two adjacent vertices receive different colours, and for every non-isolated vertex $v$, some colour appears exactly once on the neighbourhood of $v$.…

Combinatorics · Mathematics 2025-05-01 Chun-Hung Liu , Bruce Reed

We present fixed parameter tractable algorithms for the conflict-free coloring problem on graphs. Given a graph $G=(V,E)$, \emph{conflict-free coloring} of $G$ refers to coloring a subset of $V$ such that for every vertex $v$, there is a…

Data Structures and Algorithms · Computer Science 2019-05-07 Akanksha Agrawal , Pradeesha Ashok , Meghana M Reddy , Saket Saurabh , Dolly Yadav

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

We consider the single-conflict coloring problem, a graph coloring problem in which each edge of a graph receives a forbidden ordered color pair. The task is to find a vertex coloring such that no two adjacent vertices receive a pair of…

Combinatorics · Mathematics 2026-03-16 Peter Bradshaw , Tomáš Masařík

For $k\geq 1$, a $k$-colouring $c$ of $G$ is a mapping from $V(G)$ to $\{1,2,\ldots,k\}$ such that $c(u)\neq c(v)$ for any two non-adjacent vertices $u$ and $v$. The $k$-Colouring problem is to decide if a graph $G$ has a $k$-colouring. For…

Combinatorics · Mathematics 2021-01-21 Barnaby Martin , Daniel Paulusma , Siani Smith

A proper $k$-colouring of a graph $G$ is called $h$-conflict-free if every vertex $v$ has at least $\min\, \{h, {\rm deg}(v)\}$ colours appearing exactly once in its neighbourhood. Let $\chi_{\rm pcf}^h(G)$ denote the minimum $k$ such that…

Combinatorics · Mathematics 2026-02-12 Quentin Chuet , Tianjiao Dai , Qiancheng Ouyang , François Pirot

Given an undirected graph $G = (V,E)$, a conflict-free coloring with respect to open neighborhoods (CFON coloring) is a vertex coloring such that every vertex has a uniquely colored vertex in its open neighborhood. The minimum number of…

Combinatorics · Mathematics 2020-10-02 Sriram Bhyravarapu , Subrahmanyam Kalyanasundaram

Given a graph G, a q-open neighborhood conflict-free coloring or q-ONCF-coloring is a vertex coloring $c:V(G) \rightarrow \{1,2,\ldots,q\}$ such that for each vertex $v \in V(G)$ there is a vertex in $N(v)$ that is uniquely colored from the…

Computational Complexity · Computer Science 2019-05-02 Hans L. Bodlaender , Sudeshna Kolay , Astrid Pieterse

A $k$-uniform hypergraph $H = (V, E)$ is $k$-partite if $V$ can be partitioned into $k$ sets $V_1, \ldots, V_k$ such that every edge in $E$ contains precisely one vertex from each $V_i$. We call such a graph $n$-balanced if $|V_i| = n$ for…

Combinatorics · Mathematics 2024-07-26 Abhishek Dhawan

For a positive integer $k$ and graph $G=(V,E)$, a $k$-colouring of $G$ is a mapping $c: V\rightarrow\{1,2,\ldots,k\}$ such that $c(u)\neq c(v)$ whenever $uv\in E$. The $k$-Colouring problem is to decide, for a given $G$, whether a…

Computational Complexity · Computer Science 2014-07-08 Shenwei Huang , Matthew Johnson , Daniël Paulusma

For a fixed integer, the $k$-Colouring problem is to decide if the vertices of a graph can be coloured with at most $k$ colours for an integer $k$, such that no two adjacent vertices are coloured alike. A graph $G$ is $H$-free if $G$ does…

Combinatorics · Mathematics 2021-11-24 Barnaby Martin , Daniel Paulusma , Siani Smith