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The domatic number of a graph is the maximum number of vertex disjoint dominating sets that partition the vertex set of the graph. In this paper we consider the fractional variant of this notion. Graphs with fractional domatic number 1 are…

Combinatorics · Mathematics 2023-10-17 Maximilien Gadouleau , Nathaniel Harms , George B. Mertzios , Viktor Zamaraev

Given a graph $G$, a dominating set of $G$ is a set $S$ of vertices such that each vertex not in $S$ has a neighbor in $S$. The domination number of $G$, denoted $\gamma(G)$, is the minimum size of a dominating set of $G$. The independent…

Combinatorics · Mathematics 2021-07-02 Eun-Kyung Cho , Ilkyoo Choi , Boram Park

Let $\gamma(G)$ and $i(G)$ be the domination number and the independent domination number of $G$, respectively. Rad and Volkmann posted a conjecture that $i(G)/ \gamma(G) \leq \Delta(G)/2$ for any graph $G$, where $\Delta(G)$ is its maximum…

Combinatorics · Mathematics 2016-07-08 Shaohui Wang , Bing Wei

For any graph G = (V, E) and proportion $p\in(0,1]$, a set $S\subseteq V$ is a p-dominating set if $\frac{|N[S]|}{|V|}\geq p$. The $p$-domination number $\gamma_{p}(G)$ equals the minimum cardinality of a $p$-dominating set in G. For a…

Combinatorics · Mathematics 2022-01-12 L. Philo Nithya , Joseph Varghese Kureethara

A set $S$ of vertices in a graph $G$ is a dominating set if every vertex not in $S$ is adjacent to a vertex in $S$. If, in addition, $S$ is an independent set, then $S$ is an independent dominating set. The independent domination number…

Discrete Mathematics · Computer Science 2020-01-10 A. Akbari , S. Akbari , A. Doosthosseini , Z. Hadizadeh , Michael A. Henning , A. Naraghi

An independent dominating set of a graph, also known as a maximal independent set, is a set $S$ of pairwise non-adjacent vertices such that every vertex not in $S$ is adjacent to some vertex in $S$. We prove that for $\Delta=4$ or…

Combinatorics · Mathematics 2022-11-30 Eun-Kyung Cho , Jinha Kim , Minki Kim , Sang-il Oum

Weighted independent domination is an NP-hard graph problem, which remains computationally intractable in many restricted graph classes. In particular, the problem is NP-hard in the classes of sat-graphs and chordal graphs. We strengthen…

Discrete Mathematics · Computer Science 2017-05-23 Vadim Lozin , Dmitriy Malyshev , Raffaele Mosca , Viktor Zamaraev

Let $G=(V,E)$ be a simple graph. A set $I\subseteq V$ is an independent set, if no two of its members are adjacent in $G$. The $k$-independent graph of $G$, $I_k (G)$, is defined to be the graph whose vertices correspond to the independent…

Combinatorics · Mathematics 2020-01-03 Davood Fatehi , Saeid Alikhani , Abdul Jalil M. Khalaf

In this paper we initialize the study of independent domination in directed graphs. We show that an independent dominating set of an orientation of a graph is also an independent dominating set of the underlying graph, but that the converse…

Combinatorics · Mathematics 2019-09-12 Michael Cary , Jonathan Cary , Savari Prabhu

Given a simple graph $G$, a dominating set in $G$ is a set of vertices $S$ such that every vertex not in $S$ has a neighbor in $S$. Denote the domination number, which is the size of any minimum dominating set of $G$, by $\gamma(G)$. For…

Combinatorics · Mathematics 2020-07-09 Randy Davila , Elliot Krop

The dominating graph of a graph G is a graph whose vertices correspond to the dominating sets of G and two vertices are adjacent whenever their corresponding dominating sets differ in exactly one vertex. Studying properties of dominating…

Combinatorics · Mathematics 2022-12-12 Alireza Mofidi

A set $S$ of vertices in a graph $G = (V, E)$ is called {\em cycle independent} if the induced subgraph $\langle S\rangle$ is acyclic, and called {\em odd-cycle indepdendet} if $\langle S\rangle$ is bipartite. A set $S$ is {\em cycle…

Combinatorics · Mathematics 2015-05-12 Amy Grady , Fiona Knoll , Renu Laskar , Drew J. Lipman

The independent domination number $i(G)$ of a graph $G$ is the minimum cardinality of a maximal independent set of $G$, also called an $i(G)$-set. The $i$-graph of $G$ is the graph whose vertices correspond to the $i(G)$-sets, and where two…

Combinatorics · Mathematics 2023-05-30 Richard Brewster , Kieka Mynhardt , Laura Teshima

A set $S$ of vertices in a graph $G$ is a dominating set of $G$ if every vertex not in $S$ is adjacent to a vertex in~$S$. An independent dominating set in $G$ is a dominating set of $G$ with the additional property that it is an…

Combinatorics · Mathematics 2025-10-17 Boštjan Brešar , Tanja Dravec , Michael A. Henning

Let $\gamma(G)$ denote the domination number of a graph $G$. A vertex $v\in V(G)$ is called a \emph{critical vertex} of $G$ if $\gamma(G-v)=\gamma(G)-1$. A graph is called \emph{vertex-critical} if every vertex of it is critical. In this…

Combinatorics · Mathematics 2022-08-31 Weisheng Zhao , Ying Li , Ruizhi Lin

An independent coalition in a graph $G$ consists of two disjoint sets of vertices $V_1$ and $V_2$ neither of which is an independent dominating set but whose union $V_1 \cup V_2$ is an independent dominating set. An independent coalition…

Combinatorics · Mathematics 2024-07-29 Mohammad Reza Samadzadeh , Doost Ali Mojdeh

Let $G$ be a graph and let $S\subseteq V(G)$. The set $S$ is a double outer-independent dominating set of $G$ if $|N[v]\cap D|\geq2$, for all $v\in V(G)$, and $V(G)\setminus S$ is independent. Similarly, $S$ is a $2$-outer-independent…

Combinatorics · Mathematics 2021-03-26 Doost Ali Mojdeh , Iztok Peterin , Babak Samadi , Ismael G. Yero

Let $\gamma(G)$ and $\gamma_t(G)$ denote the domination number and the total domination number, respectively, of a graph $G$ with no isolated vertices. It is well-known that $\gamma_t(G) \leq 2\gamma(G)$. We provide a characterization of a…

Combinatorics · Mathematics 2023-06-22 Selim Bahadır , Didem Gözüpek

An efficient dominating set (or perfect code) in a graph is a set of vertices the closed neighborhoods of which partition the vertex set of the graph. The minimum weight efficient domination problem is the problem of finding an efficient…

Discrete Mathematics · Computer Science 2014-11-26 Andreas Brandstädt , Pavel Fičur , Arne Leitert , Martin Milanič

In the Independent set problem, the input is a graph $G$, every vertex has a non-negative integer weight, and the task is to find a set $S$ of pairwise non-adjacent vertices, maximizing the total weight of the vertices in $S$. We give an…

Data Structures and Algorithms · Computer Science 2015-09-02 Daniel Lokshtanov , Marcin Pilipczuk , Erik Jan van Leeuwen