A set S of vertices in a graph G is a total dominating set if every vertex of G is adjacent to some vertex in S. The total domination number γt(G) is the minimum cardinality of a total 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 investigate relationships between the annihilation number and the total domination number of a graph. Let T be a tree of order n<2. We show that γt(T)≤a(T)+1, and we characterize the extremal trees achieving equality in this bound. © 2012 Elsevier B.V. All rights reserved.
Desormeaux, W. J., Haynes, T. W., & Henning, M. A. (2013). Relating the annihilation number and the total domination number of a tree. Discrete Applied Mathematics, 161(3), 349–354. https://doi.org/10.1016/j.dam.2012.09.006