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The \emph{genus} $\mathrm{g}(G)$ of a graph $G$ is the minimum $g$ such that $G$ has an embedding on the orientable surface $M_g$ of genus $g$. A drawing of a graph on a surface is \emph{independently even} if every pair of nonadjacent…

Combinatorics · Mathematics 2019-03-21 Radoslav Fulek , Jan Kynčl

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

Global forcing number and maximum anti-forcing number of matchable graphs (graphs with a perfect matching) were proposed in completely different situations with applications in theoretical chemistry. Surprisingly for bipartite graphs and…

Combinatorics · Mathematics 2025-02-18 Yaxian Zhang , Yan Wu , Heping Zhang

Zero forcing is an iterative graph coloring process studied for its wide array of applications. In this process, the vertices of the graph are initially designated as blue or white, and a zero forcing set is a set of initially blue vertices…

Combinatorics · Mathematics 2026-03-23 Asher Brown , Mark Hunnell , Za'Kiyah Toomer-Sanders , Sarah Weber

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

We study the minimum rank of a (simple, undirected) graph, which is the minimum rank among all matrices in a space determined by the graph. We determine the exact set of graphs on eight vertices for which the nullity of a minimum rank…

Combinatorics · Mathematics 2025-06-13 Wayne Barrett , Mark Hunnell , John Hutchens , John Sinkovic

The \emph{matching preclusion number} of a graph is the minimum number of edges whose deletion results in a graph that has neither perfect matchings nor almost perfect matchings. As a generalization, Liu and Liu recently introduced the…

Combinatorics · Mathematics 2023-06-22 Tianlong Ma , Yaping Mao , Eddie Cheng , Christopher Melekian

The crossing number of a graph $G$ denotes the minimum number of crossings in any planar drawing of $G$. In this short note, we confirm a long-standing conjecture posed by Pach, Spencer, and T\'oth over 25 years ago, establishing an optimal…

Combinatorics · Mathematics 2025-02-05 Kaizhe Chen , Jie Ma

Zero forcing is a graph propagation process for which vertices fill-in (or propagate information to) neighbor vertices if all neighbors except for one, are filled. The zero-forcing number is the smallest number of vertices that must be…

Combinatorics · Mathematics 2024-10-24 Heather LeClair , Tim Spilde , Sarah Anderson , Brenda Kroschel

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

For any graph $G$, we define the power $\pi(G)$ as the minimum of the largest number of neighbors in a $\gamma$-set of $G$, of any vertex, taken over all $\gamma$-sets of $G$. We show that $\gamma(G\square H)\geq \frac{\pi(G)}{2\pi(G)…

Combinatorics · Mathematics 2025-09-08 Elliot Krop , Kimber Wolff

Probabilistic zero-forcing is a coloring process on a graph. In this process, an initial set of vertices is colored blue, and the remaining vertices are colored white. At each time step, blue vertices have a non-zero probability of forcing…

Combinatorics · Mathematics 2020-10-26 David Hu , Alec Sun

The bondage number b(G) of a graph G is the smallest number of edges whose removal from G results in a graph with larger domination number. In this paper we present new upper bounds for b(G) in terms of girth, order and Euler…

Combinatorics · Mathematics 2012-08-31 Vladimir Samodivkin

The distinguishing number of a graph $G$, denoted $D(G)$, is the minimum number of colors needed to produce a coloring of the vertices of $G$ so that every nontrivial isomorphism interchanges vertices of different colors. A list assignment…

Combinatorics · Mathematics 2017-07-07 Michael Ferrara , Zoltan Furedi , Sogol Jahanbekam , Paul Wenger

Over the past 10 years, there has been considerable interest in exploring questions connecting dimension for posets with graph theoretic properties of their cover graphs and order diagrams, especially with the concepts of planarity and…

Combinatorics · Mathematics 2023-04-18 Jędrzej Hodor , William T. Trotter

We consider straight line drawings of a planar graph $G$ with possible edge crossings. The \emph{untangling problem} is to eliminate all edge crossings by moving as few vertices as possible to new positions. Let $fix(G)$ denote the maximum…

Computational Geometry · Computer Science 2011-11-14 Alexander Ravsky , Oleg Verbitsky

In this paper, we propose computational approaches for the zero forcing problem, the connected zero forcing problem, and the problem of forcing a graph within a specified number of timesteps. Our approaches are based on a combination of…

Discrete Mathematics · Computer Science 2018-09-20 Boris Brimkov , Caleb C. Fast , Illya V. Hicks

Zero forcing is an iterative graph coloring process whereby a colored vertex with a single uncolored neighbor forces that neighbor to be colored. It is NP-hard to find a minimum zero forcing set - a smallest set of initially colored…

Discrete Mathematics · Computer Science 2016-07-05 Boris Brimkov

Gentner and Rautenbach conjectured that the size of a minimum zero forcing set in a connected graph on $n$ vertices with maximum degree $3$ is at most $\frac{1}{3}n+2$. We disprove this conjecture by constructing a collection of connected…

Combinatorics · Mathematics 2017-12-15 António Girão , Gábor Mészáros , Stephen G. Z. Smith

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