فهرست نشریات علمی دسترسی آزاد ایران

A Roman dominating function on a graph $G = (V,E)$ is a function $f : V\longrightarrow \{0, 1, 2\}$ satisfying the condition that every vertex $v$ for which $f (v) = 0$ is adjacent to at least one vertex $u$ for which $f (u) = 2$. The weight of a Roman dominating function is the value $w(f)=\sum_{v\in V}f(v)$. The Roman domination number of a graph $G$, denoted by $\gamma_R(G)$, equals the minimum weight of a Roman dominating function on G. The Roman game domination subdivision number of a graph $G$ is defined by the following game. Two players $\mathcal D$ and $\mathcal A$, $\mathcal D$ playing first, alternately mark or subdivide an edge of $G$ which is not yet marked nor subdivided. The game ends when all the edges of $G$ are marked or subdivided and results in a new graph $G'$. The purpose of $\mathcal D$ is to minimize the Roman domination number $\gamma_R(G')$ of $G'$ while $\mathcal A$ tries to maximize it. If both $\mathcal A$ and $\mathcal D$ play according to their optimal strategies, $\gamma_R(G')$ is well defined. We call this number the {\em Roman game domination subdivision number} of $G$ and denote it by $\gamma_{Rgs}(G)$. In this paper we initiate the study of the Roman game domination subdivision number of a graph and present sharp bounds on the Roman game domination subdivision number of a tree.