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Let ${\rm dim}(G)$ and $D(G)$ respectively denote the metric dimension and the distinguishing number of a graph $G$. It is proved that $D(G) \le {\rm dim}(G)+1$ holds for every connected graph $G$. Among trees, exactly paths and stars…

Combinatorics · Mathematics 2025-07-08 Meysam Korivand , Nasrin Soltankhah , Sandi Klavžar

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

The status of a vertex $x$ in a graph is the sum of the distances between $x$ and all other vertices. Let $G$ be a connected graph. The status sequence of $G$ is the list of the statuses of all vertices arranged in nondecreasing order. $G$…

Combinatorics · Mathematics 2019-01-29 Pu Qiao , Xingzhi Zhan

Let ${\rm gp}(G)$ be the general position number of a graph $G$. It is proved that ${\rm gp}(G-x)\leq 2{\rm gp}(G)$ holds for any vertex $x$ of a connected graph $G$ and that if $x$ lies in some ${\rm gp}$-set of $G$, then ${\rm gp}(G) - 1…

Combinatorics · Mathematics 2025-12-10 Pakanun Dokyeesun , Sandi Klavžar , Jing Tian

Let $G$ be a graph. Assume that to each vertex of a set of vertices $S\subseteq V(G)$ a robot is assigned. At each stage one robot can move to a neighbouring vertex. Then $S$ is a mobile general position set of $G$ if there exists a…

Combinatorics · Mathematics 2024-06-24 Sandi Klavžar , Aditi Krishnakumar , James Tuite , Ismael Yero

A graph in which all minimal zero forcing sets are in fact minimum size is called ``well-forced." This paper characterizes well-forced trees and presents an algorithm for determining which trees are well-forced. Additionally, we…

Combinatorics · Mathematics 2023-12-25 Cheryl Grood , Ruth Haas , Bonnie Jacob , Erika King , Shahla Nasserasr

A dynamic coloring of the vertices of a graph $G$ starts with an initial subset $S$ of colored vertices, with all remaining vertices being non-colored. At each discrete time interval, a colored vertex with exactly one non-colored neighbor…

Combinatorics · Mathematics 2017-08-18 Randy Davila , Michael Henning

For an integer $k$, a $k$-tree is a tree with maximum degree at most $k$. More generally, if $f$ is an integer-valued function on vertices, an $f$-tree is a tree in which each vertex $v$ has degree at most $f(v)$. Let $c(G)$ denote the…

Combinatorics · Mathematics 2019-07-02 M. N. Ellingham , Songling Shan , Dong Ye , Xiaoya Zha

The zero forcing number is a graph invariant introduced to study the minimum rank of the graph. In 2008, Aazami proved the NP-hardness of computing the zero forcing number of a simple undirected graph. We complete this NP-hardness result by…

Discrete Mathematics · Computer Science 2015-06-09 Maguy Trefois , Jean-Charles Delvenne

Harary et al. and Klein and Randic proposed the forcing number of a perfect matching in mathematics and chemistry, respectively. In detail, the forcing number of a perfect matching M of a graph G is the smallest cardinality of subsets of M…

Combinatorics · Mathematics 2021-10-11 Shuang Zhao

We prove that for every tree $T$ which is not an edge, for almost every graph $G$ which does not contain $T$ as an induced subgraph, $V(G)$ has a partition into $\alpha(T)-1$ parts certifying this fact. Each part induces a graph which is…

Combinatorics · Mathematics 2025-06-03 Bruce Reed , Yelena Yuditsky

Motivated by a conjecture from the automated conjecturing program TxGraffiti, in this paper the relationship between the zero forcing number, $Z(G)$, and the vertex independence number, $\alpha(G)$, of cubic and subcubic graphs is explored.…

Combinatorics · Mathematics 2024-11-04 Houston Schuerger , Nathan Warnberg , Michael Young

Let $G$ be a graph, and $Z$ a subset of its vertices, which we color black, while the remaining are colored white. We define the skew color change rule as follows: if $u$ is a vertex of $G$, and exactly one of its neighbors $v$, is white,…

Combinatorics · Mathematics 2014-05-16 Luz M. DeAlba

Let $G$ be a simple graph with $2n$ vertices and a perfect matching. We denote by $f(G)$ and $F(G)$ the minimum and maximum forcing number of $G$, respectively. Hetyei obtained that the maximum number of edges of graphs $G$ with a unique…

Combinatorics · Mathematics 2022-11-23 Qianqian Liu , Heping Zhang

The \emph{zero forcing number} $Z(G)$ of a graph $G$ is the minimum cardinality of a set $S$ of black vertices (whereas vertices in $V(G)\setminusS$ are colored white) such that $V(G)$ is turned black after finitely many applications of…

Combinatorics · Mathematics 2012-08-20 Cong X. Kang , Eunjeong Yi

The general position problem for graphs was inspired by the no-three-in-line problem from discrete geometry. A set $S$ of vertices of a graph $G$ is a \emph{general position set} if no shortest path in $G$ contains three or more vertices of…

Combinatorics · Mathematics 2024-04-02 Elias John Thomas , Ullas Chandran , James Tuite , Gabriele Di Stefano

A connected forcing set of a graph is a zero forcing set that induces a connected subgraph. In this paper, we introduce and study CF-dense graphs -- graphs in which every vertex belongs to some minimum connected forcing set. We identify…

Combinatorics · Mathematics 2025-07-16 Boris Brimkov , Randy Davila , Houston Schuerger

The general position problem is to find the cardinality of a largest vertex subset S such that no triple of vertices of S lie on a common geodesic. For a connected graph G, the cardinality of S is denoted by gp(G) and called gp-number (or…

Combinatorics · Mathematics 2020-02-11 Yan Yao , Mengya He , Shengjin Ji , Guang Li

In 1966, Cummins introduced the "tree graph": the tree graph $\mathbf{T}(G)$ of a graph $G$ (possibly infinite) has all its spanning trees as vertices, and distinct such trees correspond to adjacent vertices if they differ in just one edge,…

Combinatorics · Mathematics 2021-06-21 Suresh Dara , S. M. Hegde , Venkateshwarlu Deva , S. B. Rao , Thomas Zaslavsky

Zero forcing is an iterative graph coloring process, where given a set of initially colored vertices, a colored vertex with a single uncolored neighbor causes that neighbor to become colored. A zero forcing set is a set of initially colored…