Total domination number of middle graphs

Farshad Kazemnejad (Faculty of Basic Sciences, Department of Mathematics, Ilam University, Iran)
Behnaz Pahlavsay (Department of Mathematics, Hokkaido University, Kita 10, Nishi 8, Kita-Ku, Japan)
Elisa Palezzato (Department of Mathematics, Hokkaido University, Kita 10, Nishi 8, Kita-Ku, Japan)
Michele Torielli (Department of Mathematics, GI-CoRE GSB, Hokkaido University, Kita 10, Nishi 8, Kita-Ku, Japan)

Electronic Journal of Graph Theory and Applications (EJGTA)
Vol 10, No 1 (2022): Electronic Journal of Graph Theory and Applications

A total dominating set of a graph G with no isolated vertices is a subset S of the vertex set such that every vertex of G is adjacent to a vertex in S. The total domination number of G is the minimum cardinality of a total dominating set. In this paper, we study the total domination number of middle graphs. Indeed, we obtain tight bounds for this number in terms of the order of the graph. We also compute the total domination number of the middle graph of some known families of graphs explicitly. Moreover, some Nordhaus-Gaddum-like relations are presented for the total domination number of middle graphs.