Relating the annihilation number and the Roman domination
Acta mathematica Universitatis Comenianae, Tome 87 (2018) no. 1, pp. 1-13
R. Khoeilar; H. Aram; S. M. Sheikholeslami; L. Volkmann; R. Khoeilar; H. Aram; S. M. Sheikholeslami; L. Volkmann. Relating the annihilation number and the Roman domination. Acta mathematica Universitatis Comenianae, Tome 87 (2018) no. 1, pp. 1-13. http://geodesic.mathdoc.fr/item/AMUC_2018_87_1_a0/
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     author = {R. Khoeilar and H. Aram and S. M. Sheikholeslami and L. Volkmann and R. Khoeilar and H. Aram and S. M. Sheikholeslami and L. Volkmann},
     title = { Relating the annihilation number and the {Roman} domination},
     journal = {Acta mathematica Universitatis Comenianae},
     pages = {1--13},
     year = {2018},
     volume = {87},
     number = {1},
     url = {http://geodesic.mathdoc.fr/item/AMUC_2018_87_1_a0/}
}
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Voir la notice de l'article provenant de la source Comenius University

A {\em Roman dominating function} (RDF) on a graph $G$ is a labeling$f\:$V (G)\rightarrow \{0, 1, 2\}$ such that every vertex withlabel 0 has a neighbor with label 2. The {\em weight} of an RDF$f$ is the value $\omega(f)=\sum_{v\in V}f (v)$. The {\em Romandomination number} of a graph $G$, denoted by $\gamma_R(G)$,equals the minimum weight of an RDF on G. The annihilation number$a(G)$ is the largest integer $k$ such that the sum of the first$k$ terms of the non-decreasing degree sequence of $G$ is at mostthe number of edges in $G$. In this paper, we prove that for anytree $T$ of order at least two, $\gamma_{R}(T)\le\frac{4a(T)+2}{3}$.