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We investigate how the algebraic connectivity of a graph changes by relocating a connected branch from one vertex to another vertex, and then minimize the algebraic connectivity among all connected graphs of order $n$ with fixed domination…

Combinatorics · Mathematics 2013-11-01 Yi-Zheng Fan , Ying-Ying Tan

For a graph $G,$ the set $D \subseteq V(G)$ is a porous exponential dominating set if $1 \le \sum_{d \in D} \left( 2 \right)^{1-dist(d,v)}$ for every $v \in V(G),$ where $dist(d,v)$ denotes the length of the shortest $dv$ path. The porous…

Combinatorics · Mathematics 2018-03-05 Michael Dairyko , Michael Young

Several researchers have recently explored various graph parameters that can or cannot be characterized by the spectrum of a matrix associated with a graph. In this paper we show that several NP-hard zero forcing numbers are not…

Combinatorics · Mathematics 2022-04-25 Aida Abiad , Boris Brimkov , Jane Breen , Thomas R. Cameron , Himanshu Gupta , Ralihe R. Villagrán

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

We design logic circuits based on the notion of zero forcing on graphs; each gate of the circuits is a gadget in which zero forcing is performed. We show that such circuits can evaluate every monotone Boolean function. By using two vertices…

Discrete Mathematics · Computer Science 2017-01-12 Daniel Burgarth , Vittorio Giovannetti , Leslie Hogben , Simone Severini , Michael Young

In this paper we begin the study of well-failed graphs, that is, graphs in which every maximal failed zero forcing set is a maximum failed zero forcing set, or equivalently, in which every minimal fort is a minimum fort. We characterize…

Combinatorics · Mathematics 2025-02-03 Bonnie Jacob

Lazy burning is a recently introduced variation of burning where only one set of vertices is chosen to burn in the first round. In hypergraphs, lazy burning spreads when all but one vertex in a hyperedge is burned. The lazy burning number…

Combinatorics · Mathematics 2024-12-06 Anthony Bonato , Caleb Jones , Trent G. Marbach , Teddy Mishura , Zhiyuan Zhang

A power dominating set of a graph is a set of vertices that observes every vertex in the graph by combining classical domination with an iterative propagation process arising from electrical circuit theory. In this paper, we study the power…

Combinatorics · Mathematics 2018-05-29 Boris Brimkov , Rutvik Patel , Varun Suriyanarayana , Alexander Teich

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

The anti-forcing number of a perfect matching $M$ of a graph $G$ is the minimal number of edges not in $M$ whose removal to make $M$ as a unique perfect matching of the resulting graph. The set of anti-forcing numbers of all perfect…

Combinatorics · Mathematics 2016-07-20 Kai Deng , Heping Zhang

We provide a short proof of a conjecture of Davila and Kenter concerning a lower bound on the zero forcing number $Z(G)$ of a graph $G$. More specifically, we show that $Z(G)\geq (g-2)(\delta-2)+2$ for every graph $G$ of girth $g$ at least…

Combinatorics · Mathematics 2017-05-24 M. Fürst , D. Rautenbach

The power domination problem focuses on finding the optimal placement of phase measurement units (PMUs) to monitor an electrical power network. In the context of graphs, the power domination number of a graph $G$, denoted $\gamma_P(G)$, is…

Combinatorics · Mathematics 2022-09-09 Sarah E. Anderson , Kirsti Kuenzel

This paper surveys results about token addition and removal (TAR) reconfiguration for several well-known vertex set parameters including domination, power domination, standard zero forcing, and PSD zero forcing. We also expand the range of…

Combinatorics · Mathematics 2025-09-30 Bryan A. Curtis , Mary Flagg , Leslie Hogben

The concept of Roman domination has been a subject of intrigue for more than two decades with the fundamental Roman domination problem standing out as one of the most significant challenges in this field. This article studies a practically…

Combinatorics · Mathematics 2023-12-25 Bojan Nikolić , Marko Djukanović , Milana Grbić , Dragan Matić

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

Locating-dominating codes have been studied widely since their introduction in the 1980s by Slater and Rall. In this paper, we concentrate on vertices that must belong to all minimum locating-dominating codes in a graph. We call them…

Combinatorics · Mathematics 2026-05-06 Ville Junnila , Tero Laihonen , Havu Miikonen

In this paper, we first show that the power domination number of a connected $4$-regular claw-free graph on $n$ vertices is at most $\frac{n+1}{5}$, and the bound is sharp. The statement partly disprove the conjecture presented by Dorbec et…

Combinatorics · Mathematics 2018-08-09 Changhong Lu , Rui Mao , Bing Wang

Eternal domination is a dynamic process by which a graph is protected from an infinite sequence of vertex intrusions. In eternal distance-$k$ domination, guards initially occupy the vertices of a distance-$k$ dominating set. After a vertex…

Combinatorics · Mathematics 2022-11-21 Danielle Cox , Erin Meger , M. E. Messinger

Probabilistic zero forcing is a graph coloring process in which blue vertices "infect" (color blue) white vertices with a probability proportional to the number of neighboring blue vertices. We introduce reversion probabilistic zero forcing…

Combinatorics · Mathematics 2024-04-24 Zachary Brennan

A numbering $f$ of a graph $G$ of order $n$ is a labeling that assigns distinct elements of the set $\left\{ 1,2,\ldots ,n\right\} $ to the vertices of $G$. The strength $\textrm{str}_{f}\left( G\right)$ of a numbering $f:V\left( G\right)…

Combinatorics · Mathematics 2023-04-04 Yukio Takahashi , Rikio Ichishima , Francesc A. Muntaner-Batle