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Let $S$ be a set of vertices of a graph $G$. Let $cl(S)$ be the set of vertices built from $S$, by iteratively applying the following propagation rule: if a vertex and all but exactly one of its neighbors are in $cl(S)$, then the remaining…

Combinatorics · Mathematics 2019-08-09 Najibeh Shahbaznejad , Ignacio M. Pelayo , Adel P. Kazemi

A forcing set for a perfect matching of a graph is defined as a subset of the edges of that perfect matching such that there exists a unique perfect matching containing it. A complete forcing set for a graph is a subset of its edges, such…

Combinatorics · Mathematics 2024-09-27 Javad B. Ebrahimi , Aref Nemayande , Elahe Tohidi

Zero forcing (also called graph infection) on a simple, undirected graph $G$ is based on the color-change rule: If each vertex of $G$ is colored either white or black, and vertex $v$ is a black vertex with only one white neighbor $w$, then…

Combinatorics · Mathematics 2014-10-21 Leslie Hogben , My Huynh , Nicole Kingsley , Sarah Meyer , Shanise Walker , Michael Young

The zero forcing number is the minimum number of black vertices that can turn a white graph black following a single neighbour colour forcing rule. The zero forcing number provides topological information about linear algebra on graphs,…

Combinatorics · Mathematics 2021-02-10 Alexei Vazquez

A graph G is (a:b)-colorable if there exists an assignment of b-element subsets of {1,...,a} to vertices of G such that sets assigned to adjacent vertices are disjoint. We first show that for every triangle-free planar graph G and a vertex…

Combinatorics · Mathematics 2018-09-17 Zdeněk Dvořák , Xiaolan Hu

Let $G$ be a graph and $f:V(G)\rightarrow \mathbb{N}$ be a function. An $f$-coloring of a graph $G$ is an edge coloring such that each color appears at each vertex $v\in V(G)$ at most $f (v)$ times. The minimum number of colors needed to…

Combinatorics · Mathematics 2015-01-20 S. Akbari , M. Chavooshi , M. Ghanbari , R. Manaviyat

Let $G$ be a simple graph whose vertices are partitioned into two subsets, called filled vertices and empty vertices. A vertex $v$ is said to be forced by a filled vertex $u$ if $v$ is a unique empty neighbor of $u$. If we can fill all the…

Combinatorics · Mathematics 2016-09-02 Yaroslav Shitov

For any graph $G$, the First-Fit (or Grundy) chromatic number of $G$, denoted by $\chi_{_{\sf FF}}(G)$, is defined as the maximum number of colors used by the First-Fit (greedy) coloring of the vertices of $G$. We call a family…

Combinatorics · Mathematics 2016-05-16 Manouchehr Zaker

The zero forcing number of a graph $G$, denoted by $Z(G)$, is the minimum cardinality of a set $S$ of black vertices (where vertices in $V(G)\setminus S$ are colored white) such that $V(G)$ is turned black after finitely many applications…

Combinatorics · Mathematics 2017-02-20 I. Javaid , I. Irshad , M. Batool , Z. Raza

While a number of bounds are known on the zero forcing number $Z(G)$ of a graph $G$ expressed in terms of the order of a graph and maximum or minimum degree, we present two bounds that are related to the (upper) total domination number…

Combinatorics · Mathematics 2023-10-12 Boštjan Brešar , María Gracia Cornet , Tanja Dravec , Michael Henning

Coloring a graph $G$ consists in finding an assignment of colors $c: V(G)\to\{1,\ldots,p\}$ such that any pair of adjacent vertices receives different colors. The minimum integer $p$ such that a coloring exists is called the chromatic…

Discrete Mathematics · Computer Science 2019-12-25 Théo Pierron

In a graph G, a dominating set Df subset of V (G) is called a dom-forcing set if the sub-graph induced by Df must form a zero forcing set. The minimum cardinality of such a set is known as the dom-forcing number of the graph G, denoted by…

Combinatorics · Mathematics 2025-05-19 Susanth P , Charles Dominic , Premodkumar K P

Zero forcing is a binary coloring game on a graph where a set of filled vertices can force non-filled vertices to become filled following a color change rule. In 2008, the zero forcing number of a graph was shown to be an upper bound on its…

Combinatorics · Mathematics 2025-08-12 Thomas R. Cameron , Jonad Pulaj

Zero forcing in a graph refers to the evolution of vertex states under repeated application of a color change rule. Typically the states are chosen to be blue and white, and a forcing set is an initial set of blue vertices such that all of…

Combinatorics · Mathematics 2025-11-21 Daniela Ferrero , H. Tracy Hall , Leslie Hogben , Mark Hunnell , Ben Small

A tree $T$ in an edge-colored graph is a {\it proper tree} if no two adjacent edges of $T$ receive the same color. Let $G$ be a connected graph of order $n$ and $k$ be a fixed integer with $2\le k\le n$. For a vertex subset $S \subseteq…

Combinatorics · Mathematics 2016-03-30 Hong Chang , Xueliang Li , Zhongmei Qin

The zero forcing number Z(G), which is the minimum number of vertices in a zero forcing set of a graph G, is used to study the maximum nullity / minimum rank of the family of symmetric matrices described by G. It is shown that for a…

An incidence of an undirected graph G is a pair $(v,e)$ where $v$ is a vertex of $G$ and $e$ an edge of $G$ incident with $v$. Two incidences $(v,e)$ and $(w,f)$ are adjacent if one of the following holds: (i) $v = w$, (ii) $e = f$ or (iii)…

Discrete Mathematics · Computer Science 2015-01-28 Marthe Bonamy , Hervé Hocquard , Samia Kerdjoudj , André Raspaud

Let $ G $ be a graph with the vertex set $ V(G) $ and $ S $ be a subset of $ V(G) $. Let $cl(S)$ be the set of vertices built from $S$, by iteratively applying the following propagation rule: if a vertex and all of its neighbors except one…

Combinatorics · Mathematics 2021-06-28 Najibeh Shahbaznejad , Adel P Kazemi , Ignacio M Pelayo

Zero forcing is a dynamic coloring process on graphs. Initially, each vertex of a graph is assigned a color of either blue or white, and then a process begins by which blue vertices force white vertices to become blue. The zero forcing…

The concept of zero forcing involves a dynamic coloring process by which blue vertices cause white vertices to become blue, with the goal of forcing the entire graph blue while choosing as few as possible vertices to be initially blue. Past…

Combinatorics · Mathematics 2024-09-10 Sara Anderton , Kanno Mizozoe , Houston Schuerger , Andrew Schwartz