a total dominating set of a graph $g$ is a set $d$ of vertices of $g$ such that every vertex of $g$ has a neighbor in $d$. the total domination number of a graph $g$, denoted by $gamma_t(g)$, is~the minimum cardinality of a total dominating set of $g$. chellali and haynes [total and paired-domination numbers of a tree, akce international ournal of graphs and combinatorics 1 (2004), 6...