Total dominator chromatic number and Mycieleskian graphs

Abstract: A total dominator coloring of a graph $G$ is a proper coloring of $G$ in which each vertex of the graph is adjacent to every vertex of some color class. The total dominator chromatic number $\chi_d^t(G)$ of $G$ is the minimum number of color classes in a total dominator coloring of it. In [Total dominator chromatic number of a graph, submitted] the author initialed to study this number in graphs and obtained some important results. Here, we continue it in Mycieleskian graphs. We show that the total dominator chromatic number of the Mycieleskian of a graph $G$ belongs to between $\chi_d^t(G)+1$ and $\chi_d^t(G)+2$, and then characterize the family of graphs the their total dominator chromatic numbers are each of them.