Semitotal domination number of some graph operations

Author(s):  
Zeliha Kartal Yıldız ◽  
Aysun Aytaç
Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1036
Author(s):  
Abel Cabrera Martínez ◽  
Alejandro Estrada-Moreno ◽  
Juan Alberto Rodríguez-Velázquez

This paper is devoted to the study of the quasi-total strong differential of a graph, and it is a contribution to the Special Issue “Theoretical computer science and discrete mathematics” of Symmetry. Given a vertex x∈V(G) of a graph G, the neighbourhood of x is denoted by N(x). The neighbourhood of a set X⊆V(G) is defined to be N(X)=⋃x∈XN(x), while the external neighbourhood of X is defined to be Ne(X)=N(X)∖X. Now, for every set X⊆V(G) and every vertex x∈X, the external private neighbourhood of x with respect to X is defined as the set Pe(x,X)={y∈V(G)∖X:N(y)∩X={x}}. Let Xw={x∈X:Pe(x,X)≠⌀}. The strong differential of X is defined to be ∂s(X)=|Ne(X)|−|Xw|, while the quasi-total strong differential of G is defined to be ∂s*(G)=max{∂s(X):X⊆V(G)andXw⊆N(X)}. We show that the quasi-total strong differential is closely related to several graph parameters, including the domination number, the total domination number, the 2-domination number, the vertex cover number, the semitotal domination number, the strong differential, and the quasi-total Italian domination number. As a consequence of the study, we show that the problem of finding the quasi-total strong differential of a graph is NP-hard.


2019 ◽  
Vol 254 ◽  
pp. 295-298 ◽  
Author(s):  
Enqiang Zhu ◽  
Chanjuan Liu

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
S. K. Vaidya ◽  
R. M. Pandit

A dominating set is called a global dominating set if it is a dominating set of a graph G and its complement G¯. Here we explore the possibility to relate the domination number of graph G and the global domination number of the larger graph obtained from G by means of various graph operations. In this paper we consider the following problem: Does the global domination number remain invariant under any graph operations? We present an affirmative answer to this problem and establish several results.


Author(s):  
K. Uma Samundesvari ◽  
J. Maria Regila Baby
Keyword(s):  

In this paper the author have found out the medium domination number of Helm graph, Friendship graph.


2017 ◽  
Vol 7 (1) ◽  
pp. 109
Author(s):  
S. K. Vaidya ◽  
Sejal Hiteshbhai Karkar
Keyword(s):  

Author(s):  
S. Balamurugan ◽  
G. Prabakaran
Keyword(s):  

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