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We find the maximum number of maximal independent sets in two families of graphs: all graphs with $n$ vertices and at most $r$ cycles, and all such graphs that are also connected. In addition, we characterize the extremal graphs.

Combinatorics · Mathematics 2007-05-23 Chee Ying Goh , Khee Meng Koh , Bruce E. Sagan , V. Vatter

Let $G$ be a group. The power graph of $G$ is a graph with vertex set $G$ in which two distinct elements $x,y$ are adjacent if one of them is a power of the other. We characterize all groups whose power graphs have finite independence…

Combinatorics · Mathematics 2019-10-16 P. J. Cameron , S. H. Jafari

A set of vertices in a graph is called independent if no two vertices of the set are connected by an edge. In this paper we use the state matrix recursion algorithm, developed by Oh, to enumerate independent vertex sets in a grid graph and…

Combinatorics · Mathematics 2016-09-05 Seungsang Oh , Sangyop Lee

We consider numbers and sizes of independent sets in graphs with minimum degree at least $d$, when the number $n$ of vertices is large. In particular we investigate which of these graphs yield the maximum numbers of independent sets of…

Combinatorics · Mathematics 2012-10-05 Hiu-Fai Law , Colin McDiarmid

A dominating set in a graph $G$ is a set $S$ of vertices such that every vertex that does not belong to $S$ is adjacent to a vertex in $S$. The domination number $\gamma(G)$ of $G$ is the minimum cardinality of a dominating set of $G$. The…

Combinatorics · Mathematics 2022-08-16 Magda Dettlaff , Michael A. Henning , Jerzy Topp

Let $G=(V, E)$ be a graph. A set $S\subseteq V(G)$ is a {\it dominating set} of $G$ if every vertex in $V\setminus S$ is adjacent to a vertex of $S$. The {\it domination number} of $G$, denoted by $\gamma(G)$, is the cardinality of a…

Combinatorics · Mathematics 2017-04-21 Hongting Wang , Baoyindureng Wu , Xinhui An

A graph $G$ is {\em well-covered} if every maximal independent set has the same cardinality $q$. Let $i_k(G)$ denote the number of independent sets of cardinality $k$ in $G$. Brown, Dilcher, and Nowakowski conjectured that the independence…

Combinatorics · Mathematics 2014-12-16 Jonathan Cutler , Luke Pebody

A set $S \subseteq V$ is a dominating set in G if for every u \in V \ S, there exists $v \in S$ such that $(u,v) \in E$, i.e., $N[S] = V$. A dominating set $S$ is an Isolate Dominating Set} (IDS) if the induced subgraph $G[S]$ has at least…

Discrete Mathematics · Computer Science 2020-02-13 Jakkepalli Pavan Kumar , P. Venkata Subba Reddy

The Bell colouring graph $\mathcal{B}(G)$ of a graph $G$ is the graph whose vertices are the partitions of the vertex set of $G$ into independent sets, with an edge between two partitions if and only if one can be obtained from the other by…

Combinatorics · Mathematics 2026-04-15 Brian Hearn

Let G=(V,E) be a graph. A set S is independent if no two vertices from S are adjacent. The independence number alpha(G) is the cardinality of a maximum independent set, and mu(G) is the size of a maximum matching. The number…

Discrete Mathematics · Computer Science 2011-02-08 Vadim E. Levit , Eugen Mandrescu

An independent transversal (IT) in a graph with a given vertex partition is an independent set consisting of one vertex in each partition class. Several sufficient conditions are known for the existence of an IT in a given graph with a…

Data Structures and Algorithms · Computer Science 2023-10-13 Alessandra Graf , David G. Harris , Penny Haxell

In this paper, we count the number of independent sets of a type of graph $G(\mathcal{A},q)$ associated to some hyperplane arrangement $\mathcal{A}$, which is a generalization of the construction of graphical arrangements. We show that when…

Combinatorics · Mathematics 2020-07-30 Nicholas Guo , Guangyi Yue

Let $G=(V,E)$ be a simple graph. A dominating set of $G$ is a subset $S\subseteq V$ such that every vertex not in $S$ is adjacent to at least one vertex in $S$. The cardinality of a smallest dominating set of $G$, denoted by $\gamma(G)$, is…

Combinatorics · Mathematics 2021-01-13 Nima Ghanbari , Saeid Alikhani

The cycles are the only $2$-connected graphs in which any two nonadjacent vertices form a vertex cut. We generalize this fact by proving that for every integer $k\ge 3$ there exists a unique graph $G$ satisfying the following conditions:…

Combinatorics · Mathematics 2022-10-28 Yanan Hu , Xingzhi Zhan , Leilei Zhang

An identifying open code of a graph $G$ is a set $S$ of vertices that is both a separating open code (that is, $N_G(u) \cap S \ne N_G(v) \cap S$ for all distinct vertices $u$ and $v$ in $G$) and a total dominating set (that is, $N(v) \cap S…

Combinatorics · Mathematics 2024-07-16 Dipayan Chakraborty , Florent Foucaud , Michael A. Henning

The independence polynomial $i(G,x)$ of a graph $G$ is the generating function of the numbers of independent sets of each size. A graph of order $n$ is very well-covered if every maximal independent set has size $n/2$. Levit and Mandrescu…

Combinatorics · Mathematics 2017-09-26 Jason I. Brown , Ben Cameron

A bihole in a bipartite graph $G$ with partite sets $A$ and $B$ is an independent set $I$ in $G$ with $|I\cap A|=|I\cap B|$. We prove lower bounds on the largest order of biholes in balanced bipartite graphs subject to conditions involving…

Combinatorics · Mathematics 2020-04-13 Stefan Ehard , Elena Mohr , Dieter Rautenbach

An independent set in a graph is a set of pairwise non-adjacent vertices, and alpha(G) is the size of a maximum independent set in the graph G. A matching is a set of non-incident edges, while mu(G) is the cardinality of a maximum matching.…

Discrete Mathematics · Computer Science 2011-05-12 Vadim E. Levit , Eugen Mandrescu

For any graph $G=(V,E)$, a subset $S\subseteq V$ is called {\it an isolating set} of $G$ if $V\setminus N_G[S]$ is an independent set of $G$, where $N_G[S]=S\cup N_G(S)$, and {\it the isolation number} of $G$, denoted by $\iota(G)$, is the…

Combinatorics · Mathematics 2025-01-07 Shumin Zhang , Minhui Li , Fengming Dong

The independence polynomial of a graph $G$, denoted $I(G,x)$, is the generating polynomial for the number of independent sets of each size. The roots of $I(G,x)$ are called the \textit{independence roots} of $G$. It is known that for every…

Combinatorics · Mathematics 2022-06-29 Iain Beaton , Ben Cameron
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