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Given a proper total $k$-coloring $c:V(G)\cup E(G)\to\{1,2,\ldots,k\}$ of a graph $G$, we define the value of a vertex $v$ to be $c(v) + \sum_{uv \in E(G)} c(uv)$. The smallest integer $k$ such that $G$ has a proper total $k$-coloring whose…

Combinatorics · Mathematics 2016-08-08 Sarah Loeb , Jakub Przybyło , Yunfang Tang

Let $G(V,E)$ be a finite, simple, isolate-free graph. Two disjoint sets $A,B\subset V$ form a total coalition in $G$, if none of them is a total dominating set, but their union $A\cup B$ is a total dominating set. A vertex partition…

Combinatorics · Mathematics 2023-02-08 János Barát , Zoltán L. Blázsik

A proper coloring of the vertices of a graph is called a \emph{star coloring} if the union of every two color classes induces a star forest. The star chromatic number $\chi_s(G)$ is the smallest number of colors required to obtain a star…

Combinatorics · Mathematics 2021-05-17 Yuehua Bu , Daniel W. Cranston , Mickaël Montassier , André Raspaud , Weifan Wang

A graph $G$ is $d$-distinguishable if there is a coloring of the vertices with $d$ colors so that only the trivial automorphism preserves the color classes. The smallest such $d$ is the distinguishing number, $\operatorname{Dist}(G)$. The…

Combinatorics · Mathematics 2021-02-01 Debra Boutin , Sally Cockburn , Lauren Keough , Sarah Loeb , K. E. Perry , Puck Rombach

A sequence of vertices in a graph $G$ with no isolated vertices is called a total dominating sequence if every vertex in the sequence totally dominates at least one vertex that was not totally dominated by preceding vertices in the…

Combinatorics · Mathematics 2016-08-25 Boštjan Brešar , Tim Kos , Graciela Nasini , Pablo Torres

If G is a graph and H is a set of subgraphs of G, then an edge-coloring of G is called H-polychromatic if every graph from H gets all colors present in G on its edges. The H-polychromatic number of G, denoted poly_H(G), is the largest…

An adjacent vertex distinguishing coloring of a graph G is a proper edge coloring of G such that any pair of adjacent vertices are incident with distinct sets of colors. The minimum number of colors needed for an adjacent vertex…

Combinatorics · Mathematics 2012-08-14 Lianzhu Zhang , Weifan Wang , Ko-Wei Lih

A proper $[k]$-total coloring $c$ of a graph $G$ is a mapping $c$ from $V(G)\bigcup E(G)$ to $[k]=\{1,2,\cdots,k\}$ such that $c(x)\neq c(y)$ for which $x$, $y\in V(G)\bigcup E(G)$ and $x$ is adjacent to or incident with $y$. Let $\prod(v)$…

Combinatorics · Mathematics 2021-04-23 Aijun Dong , Wenwen Zhang

Let $G=(V,E)$ be a simple graph. A dominating set of $G$ is a subset $S\subseteq V$ such that every vertex not in $S$ is adjacent to at least one vertex in $S$. The cardinality of a smallest dominating set of $G$, denoted by $\gamma(G)$, is…

Combinatorics · Mathematics 2022-05-06 Nima Ghanbari

In this paper, we explore the concept of total bondage in finite graphs without isolated vertices. A vertex set $D$ is considered a total dominating set if every vertex $v$ in the graph $G$ has a neighbor in $D$. The minimum cardinality of…

Combinatorics · Mathematics 2024-01-31 E. G. K. M. Gamlath , Bing Wei

Let $G$ be a graph and $C$ a finite set of colours. A vertex colouring $f:V(G)\to C$ is complete if for any pair of distinct colours $c_1,c_2\in C$ one can find an edge $\{v_1,v_2\}\in E(G)$ such that $f(v_i)=c_i$, $i=1,2$. The achromatic…

Combinatorics · Mathematics 2021-07-20 Mirko Hornak

We study the secure domination number of the Mycielskian graph of a simple, connected, undirected graph. We give generally applicable bounds, compute secure domination numbers for Mycielskians of important families of graphs, and construct…

Combinatorics · Mathematics 2026-03-19 Kiran R. Bhutani , Anthony Christiana , Peter Ulrickson

DP-coloring (also known as correspondence coloring) is a generalization of list coloring developed recently by Dvo\v{r}\'{a}k and Postle. In this paper we introduce and study the fractional DP-chromatic number $\chi_{DP}^\ast(G)$. We…

Combinatorics · Mathematics 2019-06-04 Anton Bernshteyn , Alexandr Kostochka , Xuding Zhu

Let $G$ be a graph. A total dominating set in a graph $G$ is a set $S$ of vertices of $G$ such that every vertex in $G$ is adjacent to a vertex in $S$. Recently, the following question was proposed: "Is it true that every connected cubic…

Combinatorics · Mathematics 2023-08-30 S. Akbari , M. Azimian , A. Fazli Khani , B. Samimi , E. Zahiri

For a given graph $G$, the least integer $k\geq 2$ such that for every Abelian group $\mathcal{G}$ of order $k$ there exists a proper edge labeling $f:E(G)\rightarrow \mathcal{G}$ so that $\sum_{x\in N(u)}f(xu)\neq \sum_{x\in N(v)}f(xv)$…

Combinatorics · Mathematics 2023-06-22 Sylwia Cichacz , Jakub Przybyło

The local chromatic number of a graph G is the number of colors appearing in the most colorful closed neighborhood of a vertex minimized over all proper colorings of G. We show that two specific topological obstructions that have the same…

Combinatorics · Mathematics 2007-05-23 Gábor Simonyi , Gábor Tardos , Siniša T. Vrećica

An $r$-dynamic $k$-coloring of a graph $G$ is a proper vertex $k$-coloring such that the neighbors of any vertex $v$ receive at least $\min\{r,{\rm deg}(v)\}$ different colors. The $r$-dynamic chromatic number of $G$, $\chi_r(G)$, is…

Combinatorics · Mathematics 2014-01-28 Ali Taherkhani

The total domination number of a graph $G$ without isolated vertices is the minimum number of vertices that dominate all vertices in $G$. The total bondage number $b_t(G)$ of $G$ is the minimum number of edges whose removal enlarges the…

Combinatorics · Mathematics 2011-09-20 Fu-Tao Hu , You Lu , Jun-Ming Xu

A {\em strong edge coloring} of a graph $G$ is a proper edge coloring in which every color class is an induced matching. The {\em strong chromatic index} $\chiup_{s}'(G)$ of a graph $G$ is the minimum number of colors in a strong edge…

Combinatorics · Mathematics 2022-06-13 Tao Wang

Inspired by the phenomenon of co-channel interference in communication network, a novel graph parameter, called $r$-vertex-strongly-distinguishing total coloring (abbreviate as $D(r)$-VSDTC), is proposed in this paper. Given a graph $G$, an…

Combinatorics · Mathematics 2020-08-14 Fei Wen , Zepeng Li , Xiang'en Chen
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