Bounding the domination number of a tree in terms of its annihilation number

Document Type: Research Paper

Authors

1 Azarbaijan Shahid Madani University

2 Azarbaijan University of Tarbiat Moallem

Abstract

A set $S$ of vertices in a graph $G$ is a dominating set if every‎ ‎vertex of $V-S$ is adjacent to some vertex in $S$‎. ‎The domination‎ ‎number $\gamma(G)$ is the minimum cardinality of a dominating set‎ ‎in $G$‎. ‎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 most the number of edges in $G$‎. ‎In‎ ‎this paper‎, ‎we show that for any tree $T$ of order $n\ge 2$‎, ‎$\gamma(T)\le \frac{3a(T)+2}{4}$‎, ‎and we characterize the trees‎ ‎achieving this bound‎.

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