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In this paper, an upper bound for the perfect Italian domination number of the cartesian product of any two graphs is obtained and the exact value of this parameter for cartesian product of some special graphs are obtained. We have also…

Combinatorics · Mathematics 2021-11-16 Jismi Varghese , Aparna Lakshmanan S

The domination polynomials of binary graph operations, aside from union, join and corona, have not been widely studied. We compute and prove recurrence formulae and properties of the domination polynomials of families of graphs obtained by…

Combinatorics · Mathematics 2013-12-25 Tomer Kotek , James Preen , Peter Tittmann

Let $G$ be a graph with vertex set $V(G)$. A function $f:V(G)\rightarrow \{0,1,2\}$ is a Roman dominating function on $G$ if every vertex $v\in V(G)$ for which $f(v)=0$ is adjacent to at least one vertex $u\in V(G)$ such that $f(u)=2$. The…

Combinatorics · Mathematics 2021-05-24 Abel Cabrera Martinez , Iztok Peterin , Ismael G. Yero

For a graph $G=(V(G),E(G))$, an Italian dominating function (ID function) of $G$ is a function $f:V(G)\rightarrow \{0,1,2\}$ such that for each vertex $v\in V(G)$ with $f(v)=0$, $f(N(v))\geq2$, that is, either there is a vertex $u \in N(v)$…

Combinatorics · Mathematics 2021-08-25 Abdollah Khodkar , Doost Ali Mojdeh , Babak Samadi , Ismael G. Yero

An Italian dominating function on a digraph $D$ with vertex set $V(D)$ is defined as a function $f : V(D) \rightarrow \{0, 1, 2\}$ such that every vertex $v \in V(D)$ with $f(v) = 0$ has at least two in-neighbors assigned $1$ under $f$ or…

Discrete Mathematics · Computer Science 2020-08-25 Kijung Kim

An Italian dominating function on a (di)graph $G$ with vertex set $V(G)$ is a function $f: V(G) \to \{0, 1, 2\}$ such that every vertex $v \in V(G)$ such that $f(v) = 0$ has an (in)neighbour assigned 2 or two (in)neighbours assigned 1. We…

Combinatorics · Mathematics 2020-11-03 Christopher M. van Bommel

In this paper, we show that the Italian domination number of every lexicographic product graph $G\circ H$ can be expressed in terms of five different domination parameters of $G$. These parameters can be defined under the following unified…

Combinatorics · Mathematics 2021-05-12 A. Cabrera Martinez , A. Estrada-Moreno , J. A. Rodriguez-Velazquez

In a graph $G=(V,E)$, each vertex $v\in V$ is labelled with $0$, $1$ or $2$ such that each vertex labelled with $0$ is adjacent to at least one vertex labelled $2$ or two vertices labelled $1$. Such kind of labelling is called an Italian…

Combinatorics · Mathematics 2020-05-05 Hong Gao , Jiahuan Huang , Yanan Yin , Yuansheng Yang

For a graph $G=(V(G),E(G))$, an Italian dominating function (ID function) $f:V(G)\rightarrow\{0,1,2\}$ has the property that for every vertex $v\in V(G)$ with $f(v)=0$, either $v$ is adjacent to a vertex assigned $2$ under $f$ or $v$ is…

Combinatorics · Mathematics 2021-08-25 Babak Samadi , Morteza Alishahi , Iman Masoumi , Doost Ali Mojdeh

The aim of this paper is to obtain closed formulas for the perfect domination number, the Roman domination number and the perfect Roman domination number of lexicographic product graphs. We show that these formulas can be obtained…

Discrete Mathematics · Computer Science 2023-06-22 A. Cabrera Martinez , C. Garcia-Gomez , J. A. Rodriguez-Velazquez

In this paper we study the weak Roman domination number and the secure domination number of a graph. In particular, we obtain general bounds on these two parameters and, as a consequence of the study, we derive new inequalities of…

Combinatorics · Mathematics 2020-08-04 Magdalena Valveny , Juan Alberto Rodriguez-Velazquez

The orientable domination number, ${\rm DOM}(G)$, of a graph $G$ is the largest domination number over all orientations of $G$. In this paper, ${\rm DOM}$ is studied on different product graphs and related graph operations. The orientable…

Combinatorics · Mathematics 2022-11-07 Sarah Anderson , Boštjan Brešar , Sandi Klavžar , Kirsti Kuenzel , Douglas F. Rall

The problem of injective coloring in graphs can be revisited through two different approaches: coloring the two-step graphs and vertex partitioning of graphs into open packing sets, each of which is equivalent to the injective coloring…

Combinatorics · Mathematics 2024-06-07 Babak Samadi , Nasrin Soltankhah , Ismael G. Yero

An outer-connected dominating set for an arbitrary graph $G$ is a set $\tilde{D} \subseteq V$ such that $\tilde{D}$ is a dominating set and the induced subgraph $G [V \setminus \tilde{D}]$ be connected. In this paper, we focus on the…

Discrete Mathematics · Computer Science 2017-08-02 M. Hashemipour , M. R. Hooshmandasl , A. Shakiba

An Italian dominating function (IDF), of a graph G is a function $ f: V(G) \rightarrow \{0,1,2\} $ satisfying the condition that for every $ v\in V(G) $ with $ f(v) = 0, \sum_{ u\in N(v)} f(u) \geq 2. $ The weight of an IDF on $G$ is the…

Combinatorics · Mathematics 2022-03-01 Jismy Varghese , Aparna Lakshmanan S

Consider a finite simple digraph $D$ with vertex set $V(D)$. An Italian dominating function (IDF) on $D$ is a function $f:V(D)\rightarrow\{0,1,2\}$ satisfying every vertex $u$ with $f(u)=0$ has an in-neighbor $v$ with $f(v)=2$ or two…

Combinatorics · Mathematics 2025-08-19 Changchang Dong , Yubao Guo , Mei Lu , Lutz Volkmann

The product power throttling number of a graph is defined to study product throttling for power domination. The domination number of a graph is an upper bound for its product power throttling number. It is established that the two…

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 $G$ be a simple graph of order $n$. The domination polynomial of $G$ is the polynomial $D(G,\lambda)=\sum_{i=0}^{n} d(G,i) \lambda^{i}$, where $d(G,i)$ is the number of dominating sets of $G$ of size $i$. Every root of $D(G,\lambda)$ is…

Combinatorics · Mathematics 2012-10-12 Saeid Alikhani

Given a graph $G=(V,E)$, $f:V \rightarrow \{0,1,2 \}$ is the Italian dominating function of $G$ if $f$ satisfies $\sum_{u \in N(v)}f(u) \geq 2$ when $f(v)=0$. Denote $w(f)=\sum_{v \in V}f(v)$ as the weight of $f$. Let…

Combinatorics · Mathematics 2019-08-05 Decheng Wei , Changhong Lu
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