# Restrained roman domination in graphs

Document Type : National Conference on Labelings and Decompositions of Graphs

Authors

1 Department of Mathematics D.B.Jain College, Chennai 97 India

2 Department of Mathematics Sri Sairam Engineering College Chennai 44 India

Abstract

‎A \textit{Roman dominating function} (RDF) on a graph $G = (V,E)$ is‎ ‎defined to be a function $f:V \rightarrow \lbrace 0,1,2\rbrace$‎ ‎satisfying the condition that every vertex $u$ for which $f(u) = 0$ is‎ ‎adjacent to at least one vertex $v$ for which $f(v)=2$‎. ‎A set $S‎ ‎\subseteq V$ is a \textit{Restrained dominating set} if every vertex‎ ‎not in $S$ is adjacent to a vertex in $S$ and to a vertex in $V‎ - ‎S$‎. ‎We define a \textit{Restrained Roman dominating function} on a‎ ‎graph $G = (V,E)$ to be a function $f‎ : ‎V \rightarrow \lbrace 0,1,2‎ ‎\rbrace$ satisfying the condition that every vertex $u$ for which‎ ‎$f(u) = 0$ is adjacent to at least one vertex $v$ for which $f(v)=2$‎ ‎and at least one vertex $w$ for which $f(w) = 0$‎. ‎The \textit{weight}‎ ‎of a Restrained Roman dominating function is the value $f(V)= \sum _{u‎ ‎\in V} f(u)$‎. ‎The minimum weight of a Restrained Roman dominating‎ ‎function on a graph $G$ is called the Restrained Roman‎ ‎domination number of $G$ and denoted by $\gamma_{rR}(G)$‎. ‎In this‎ ‎paper‎, ‎we initiate a study of this parameter‎.

Keywords

Main Subjects

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### History

• Receive Date: 17 September 2013
• Revise Date: 24 January 2014
• Accept Date: 26 January 2014
• Published Online: 01 March 2015