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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…

组合数学 · 数学 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,…

组合数学 · 数学 2013-11-28 Fatemeh Alinaghipour Taklimi , Shaun Fallat , Karen Meagher

An incidence of a hypergraph $\mathcal{H}=(X,S)$ is a pair $(x,s)$ with $x\in X$, $s\in S$ and $x\in s$. Two incidences $(x,s)$ and $(x',s')$ are adjacent if (i) $x=x'$, or (ii) $\{x,x'\}\subseteq s$ or $\{x,x'\}\subseteq s'$. A proper…

组合数学 · 数学 2022-02-08 Weichan Liu , Guiying Yan

A hypergraph is "$d$-degenerate" if every subhypergraph has a vertex of degree at most $d$. A greedy algorithm colours every such hypergraph with at most $d+1$ colours. We show that this bound is tight, by constructing an $r$-uniform…

组合数学 · 数学 2014-08-18 David R. Wood

Zero forcing in graphs is a coloring process where a colored vertex can force its unique uncolored neighbor to be colored. A zero forcing set is a set of initially colored vertices capable of eventually coloring all vertices of the graph.…

组合数学 · 数学 2024-05-03 Krishna Menon , Anurag Singh

We consider the problem of covering a graph with a given number of induced subgraphs so that the maximum number of vertices in each subgraph is minimized. We prove NP-completeness of the problem, prove lower bounds, and give approximation…

离散数学 · 计算机科学 2007-05-23 Shripad Thite

An edge-coloring of a graph $G$ with colors $1,\ldots,t$ is an \emph{interval $t$-coloring} if all colors are used, and the colors of edges incident to each vertex of $G$ are distinct and form an integer interval. It is well-known that…

组合数学 · 数学 2019-12-04 Armen R. Davtyan , Gevorg M. Minasyan , Petros A. Petrosyan

A proper edge-coloring of a graph $G$ with colors $1,\ldots,t$ is called an \emph{interval cyclic $t$-coloring} if all colors are used, and the edges incident to each vertex $v\in V(G)$ are colored by $d_{G}(v)$ consecutive colors modulo…

组合数学 · 数学 2014-11-04 Petros A. Petrosyan , Sargis T. Mkhitaryan

A graph $G$ is called \emph{symmetric with respect to a functional $F_G(P)$} defined on the set of all the probability distributions on its vertex set if the distribution $P^*$ maximizing $F_G(P)$ is uniform on $V(G)$. Using the…

组合数学 · 数学 2013-11-27 Seyed Saeed Changiz Rezaei , Chris Godsil

We study the following model of disease spread in a social network. At first, all individuals are either infected or healthy. Next, in discrete rounds, the disease spreads in the network from infected to healthy individuals such that a…

计算复杂性 · 计算机科学 2024-09-04 Michal Dvořák , Dušan Knop , Šimon Schierreich

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…

组合数学 · 数学 2016-08-03 Michael Gentner , Dieter Rautenbach

We consider a random geometric hypergraph model based on an underlying bipartite graph. Nodes and hyperedges are sampled uniformly in a domain, and a node is assigned to those hyperedges that lie with a certain radius. From a modelling…

概率论 · 数学 2023-09-19 Henry-Louis de Kergorlay , Desmond J. Higham

Given two graphs $H_1$ and $H_2$, a graph is $(H_1,H_2)$-free if it contains no induced subgraph isomorphic to $H_1$ nor $H_2$. A graph $G$ is $k$-vertex-critical if every proper induced subgraph of $G$ has chromatic number less than $k$,…

组合数学 · 数学 2024-03-12 Wen Xia , Jorik Jooken , Jan Goedgebeur , Shenwei Huang

Learning a hidden hypergraph is a natural generalization of the classical group testing problem that consists in detecting unknown hypergraph $H_{un}=H(V,E)$ by carrying out edge-detecting tests. In the given paper we focus our attention…

信息论 · 计算机科学 2016-11-18 A. G. D'yachkov , I. V. Vorobyev , N. A. Polyanskii , V. Yu. Shchukin

Motivated in part by an observation that the zero forcing number for the complement of a tree on $n$ vertices is either $n-3$ or $n-1$ in one exceptional case, we consider the zero forcing number for the complement of more general graphs…

组合数学 · 数学 2023-03-13 Emelie Curl , Shaun Fallat , Ryan Moruzzi , Carolyn Reinhart , Derek Young

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…

组合数学 · 数学 2022-11-23 Qianqian Liu , Heping Zhang

We study feature propagation on graph, an inference process involved in graph representation learning tasks. It's to spread the features over the whole graph to the $t$-th orders, thus to expand the end's features. The process has been…

社会与信息网络 · 计算机科学 2018-04-18 Biao Xiang , Ziqi Liu , Jun Zhou , Xiaolong Li

We consider the problem of determining the maximum induced density of a graph H in any graph on n vertices. The limit of this density as n tends to infinity is called the inducibility of H. The exact value of this quantity is known only for…

组合数学 · 数学 2013-07-17 James Hirst

A total weighting of the vertices and edges of a hypergraph is called vertex-coloring if the total weights of the vertices yield a proper coloring of the graph, i.e., every edge contains at least two vertices with different weighted…

组合数学 · 数学 2013-12-24 Florian Pfender

A total coloring of a graph $G$ is a coloring of its vertices and edges such that no adjacent vertices, edges, and no incident vertices and edges obtain the same color. An interval total $t$-coloring of a graph $G$ is a total coloring of…

组合数学 · 数学 2014-08-12 Petros A. Petrosyan , Nerses A. Khachatryan