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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

The zero forcing number and the positive zero forcing number of a graph are two graph parameters that arise from two types of graph colourings. The zero forcing number is an upper bound on the minimum number of induced paths in the graph,…

Combinatorics · Mathematics 2013-11-28 Fatemeh Alinaghipour Taklimi , Shaun Fallat , Karen Meagher

A graph is well-(edge-)dominated if every minimal (edge) dominating set is minimum. A graph is equimatchable if every maximal matching is maximum. We study these concepts on strong product graphs. We fully characterize well-edge-dominated…

Combinatorics · Mathematics 2024-07-02 Yixin Cao , Guiqiang Mou , Jianxin Wang

Let ${\rm Z}(G)$ and ${\rm gp}(G)$ be the zero forcing number and the general position number of a graph $G$, respectively. Known results imply that ${\rm gp}(T)\ge {\rm Z}(T) + 1$ holds for every nontrivial tree $T$. It is proved that the…

Combinatorics · Mathematics 2021-12-21 Hongbo Hua , Xinying Hua , Sandi Klavžar

A leak is a vertex that is not allowed to perform a force during the zero forcing process. Leaky forcing was recently introduced as a new variation of zero forcing in order to analyze how leaks in a network disrupt the zero forcing process.…

Combinatorics · Mathematics 2020-08-18 Joseph S. Alameda , Jürgen Kritschgau , Nathan Warnberg , Michael Young

For a graph $G$ in which vertices are either black or white, a zero forcing process is an iterative vertex color changing process such that the only white neighbor of a black vertex becomes black in the next time step. A zero forcing set is…

Combinatorics · Mathematics 2025-08-26 Hau-Yi Lin , Wu-Hsiung Lin , Gerard Jennhwa Chang

For a given graph $R$, a graph $G$ is $R$-free if $G$ does not contain $R$ as an induced subgraph. It is known that every $2$-tough graph with at least three vertices has a $2$-factor. In graphs with restricted structures, it was shown that…

Combinatorics · Mathematics 2022-04-08 Elizabeth Grimm , Songling Shan , Anna Johnsen

For a degree sequence, we define the set of edges that appear in every labeled realization of that sequence as forced, while the edges that appear in none as forbidden. We examine structure of graphs whose degree sequences contain either…

Combinatorics · Mathematics 2019-11-28 Brian Cloteaux

Given a graph $G$, a set $F$ of edges is an edge dominating set if all edges in $G$ are either in $F$ or adjacent to an edge in $F$. $G$ is said to be well-edge-dominated if every minimal edge dominating set is also minimum. In 2022, it was…

Combinatorics · Mathematics 2026-01-08 Sarah E. Anderson , Kirsti Kuenzel

A set $Z$ of vertices of a graph $G$ is a zero forcing set of $G$ if initially labeling all vertices in $Z$ with $1$ and all remaining vertices of $G$ with $0$, and then, iteratively and as long as possible, changing the label of some…

Combinatorics · Mathematics 2016-08-03 Michael Gentner , Dieter Rautenbach

Let $G$ be a graph. The maximum nullity of $G$, denoted by $M(G)$, is defined to be the largest possible nullity over all real symmetric matrices $A$ whose $a_{ij}\neq 0$ for $i\neq j$, whenever two vertices $u_i$ and $u_j$ of $G$ are…

Combinatorics · Mathematics 2017-05-30 Saieed Akbari , Ebrahim Vatandoost , Yasser Golkhandy Pour

Reconfiguration graphs provide a way to represent relationships among solutions to a problem, and have been studied in many contexts. We investigate the reconfiguration graphs corresponding to minimum PSD forcing sets and minimum skew…

Combinatorics · Mathematics 2025-01-08 Novi Bong , Mary Flagg , Mark Hunnell , John Hutchens , Ryan Moruzzi , Houston Schuerger , Ben Small

The concept of zero forcing is extended from graphs to uniform hypergraphs in analogy with the way zero forcing was defined as an upper bound for the maximum nullity of the family of symmetric matrices whose nonzero pattern of entries is…

Combinatorics · Mathematics 2018-08-30 Leslie Hogben

Power domination in graphs arises from the problem of monitoring an electric power system by placing as few measurement devices in the system as possible. A power dominating set of a graph is a set of vertices that observes every vertex in…

Combinatorics · Mathematics 2017-11-15 Chassidy Bozeman , Boris Brimkov , Craig Erickson , Daniela Ferrero , Mary Flagg , Leslie Hogben

In this paper, we study (zero) forcing sets which induce connected subgraphs of a graph. The minimum cardinality of such a set is called the connected forcing number of the graph. We provide sharp upper and lower bounds on the connected…

Combinatorics · Mathematics 2016-05-10 Randy Davila , Michael Henning , Colton Magnant , Ryan Pepper

It is known that the zero forcing number of a graph is an upper bound for the maximum nullity of the graph. In this paper, we search for characteristics of a graph that guarantee the maximum nullity of the graph and the zero forcing number…

Combinatorics · Mathematics 2019-12-17 Derek Young

A graph is CIS if every maximal clique interesects every maximal stable set. Currently, no good characterization or recognition algorithm for the CIS graphs is known. We characterize graphs in which every maximal matching saturates all…

Combinatorics · Mathematics 2018-12-14 Liliana Alcón , Marisa Gutierrez , Martin Milanič

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

Zero forcing number has recently become an interesting graph parameter studied in its own right since its introduction by the "AIM Minimum Rank -- Special Graphs Work Group", whereas metric dimension is a well-known graph parameter. We…

Combinatorics · Mathematics 2014-12-11 Linda Eroh , Cong X. Kang , Eunjeong Yi

In this paper we investigate invertibility of graphs with a unique perfect matching, i.e. graphs having a unique 1-factor. We recall the new notion of the so-called negatively invertible graphs investigated by the authors in the recent…

Combinatorics · Mathematics 2016-12-08 Sona Pavlikova , Daniel Sevcovic