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This paper continues the study of a new variant of graph coloring with a connectivity constraint recently introduced by Hsieh et al. [COCOON 2024]. A path in a vertex-colored graph is called conflict-free if there is a color that appears…

Data Structures and Algorithms · Computer Science 2025-12-15 Carl Feghali , Hoang-Oanh Le , Van Bang Le

We study a generalization of the classical Hajnal-Szemer\'edi theorem to vertex-weighted graphs. Given a graph with nonnegative vertex weights, a coloring is called $\alpha$-approximately equitable up to one vertex ($\alpha$-EQ1) if, for…

Data Structures and Algorithms · Computer Science 2026-05-12 Siddharth Barman , Vignesh Viswanathan

Let $G=(V,E)$ be a graph. If $G$ is a K\"onig graph or $G$ is a graph without 3-cycles and 5-cycle, we prove that the following conditions are equivalent: $\Delta_{G}$ is pure shellable, $R/I_{\Delta}$ is Cohen-Macaulay, $G$ is unmixed…

Combinatorics · Mathematics 2015-05-04 Iván Dario Castrillón , Roberto Cruz , Enrique Reyes

An adjacent vertex distinguishing total $k$-coloring $f$ of a graph $G$ is a proper total $k$-coloring of $G$ such that no pair of adjacent vertices has the same color sets, where the color set at a vertex $v$, $C^G_f(v)$, is $\{f(v)\} \cup…

Combinatorics · Mathematics 2022-08-24 Hanna Furmańczyk , Rita Zuazua

An odd $k$-edge-coloring of a graph $G$ is a (not necessarily proper) edge-coloring with at most $k$ colors such that each non-empty color class induces a graph in which every vertex is of odd degree; similarly, if more than one color per…

Combinatorics · Mathematics 2025-06-26 Xiao-Chuan Liu , Mirko Petruševski , Xu Yang

For integers $k>0$ and $0<r \leq \Delta$ (where $r \leq k$), a conditional $(k,r)$-coloring of a graph $G$ is a proper $k$-coloring of the vertices of $G$ such that every vertex $v$ of degree $d(v)$ in $G$ is adjacent to vertices with at…

Discrete Mathematics · Computer Science 2012-01-31 P. V. Subba Reddy , K. V. Iyer

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

A well-studied concept is that of the total chromatic number. A proper total colouring of a graph is a colouring of both vertices and edges so that every pair of adjacent vertices receive different colours, every pair of adjacent edges…

Combinatorics · Mathematics 2010-09-14 Tom Coker , Karen Johannson

Let G be a graph with n vertices and suppose that for each vertex v in G, there exists a list of k colors L(v), such that there is a unique proper coloring for G from this collection of lists, then G is called a uniquely k-list colorable…

Combinatorics · Mathematics 2008-01-03 M. Ghebleh , E. S. Mahmoodian

A graph $G$ is equitably $k$-choosable if, for any given $k$-uniform list assignment $L$, $G$ is $L$-colorable and each color appears on at most $\lceil\frac{|V(G)|}{k}\rceil$ vertices. A graph is equitably $k$-colorable if the vertex set…

Combinatorics · Mathematics 2023-06-22 Aijun Dong , Jianliang Wu

A defective $k$-coloring is a coloring on the vertices of a graph using colors $1,2, \dots, k$ such that adjacent vertices may share the same color. A $(d_1,d_2)$-\emph{coloring} of a graph $G$ is a defective $2$-coloring of $G$ such that…

Combinatorics · Mathematics 2025-01-14 Pongpat Sittitrai , Wannapol Pimpasalee , Kittikorn Nakprasit

Let $X$ be a (repetitive) infinite connected simple graph with a finite upper bound $\Delta$ on the vertex degrees. The main theorem states that $X$ admits a (repetitive) limit aperiodic vertex coloring by $\Delta$ colors. This refines a…

Metric Geometry · Mathematics 2020-03-05 Jesús A. Álvarez López , Ramón Barral Lijó

A proper vertex-colouring of a graph G is said to be locally identifying if for any pair u,v of adjacent vertices with distinct closed neighbourhoods, the sets of colours in the closed neighbourhoods of u and v are different. We show that…

Combinatorics · Mathematics 2012-05-04 Florent Foucaud , Iiro Honkala , Tero Laihonen , Aline Parreau , Guillem Perarnau

Given an integer $k\ge1$, an edge-$k$-coloring of a graph $G$ is an assignment of $k$ colors $1,\ldots,k$ to the edges of $G$ such that no two adjacent edges receive the same color. A vertex-distinguishing (resp. sum-distinguishing)…

Combinatorics · Mathematics 2024-12-11 Yuping Gao , Songling Shan , Guanghui Wang

An $r$-uniform hypergraph is uniquely $k$-colorable if there exists exactly one partition of its vertex set into $k$ parts such that every edge contains at most one vertex from each part. For integers $k \ge r \ge 2$, let $\Phi_{k,r}$…

Combinatorics · Mathematics 2024-09-04 Xizhi Liu , Jie Ma , Tianhen Wang , Tianming Zhu

Let $F$ be a (possibly improper) edge-coloring of a graph $G$; a vertex coloring of $G$ is \emph{adapted to} $F$ if no color appears at the same time on an edge and on its two endpoints. If for some integer $k$, a graph $G$ is such that…

Combinatorics · Mathematics 2020-11-02 Carl Johan Casselgren , Jonas B. Granholm , André Raspaud

An edge coloring $c$ of a graph $G$ is a royal $k$-edge coloring of $G$ if the edges of $G$ are assigned nonempty subsets of the set $\{1, 2, \ldots, k\}$ in such a way that the vertex coloring obtained by assigning the union of the colors…

Combinatorics · Mathematics 2021-08-16 Akbar Ali , Gary Chartrand , James Hallas , Ping Zhang

In an undirected graph, a proper (k,i)-coloring is an assignment of a set of k colors to each vertex such that any two adjacent vertices have at most i common colors. The (k,i)-coloring problem is to compute the minimum number of colors…

Data Structures and Algorithms · Computer Science 2020-09-14 Sriram Bhyravarapu , Saurabh Joshi , Subrahmanyam Kalyanasundaram , Anjeneya Swami Kare

The paper considers the NP-hard graph vertex coloring problem, which differs from traditional problems in which it is required to color vertices with a given (or minimal) number of colors so that adjacent vertices have different colors. In…

Discrete Mathematics · Computer Science 2025-02-24 Adil Erzin , Roman Plotnikov , Georgii Zhukov

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