fr6122 Let $gamma(G)$ and $gamma_t(G)$ denote the domination number and the total domination number, respectively, of a graph $G$ with no isolated vertices.It is well-known that $gamma_t(G) leq 2gamma(G)$.We provide a characterization of a large family of graphs (including chordal graphs) satisfying $gamma_t(G)= 2gamma(G)$, strictly generalizing the results of Henning (2001) and Hou et al.
(2010), and partially answering an open question le maudit vape institut of Henning (2009).