common extremal graphs for three inequalities involving domination parameters

‎let δ(g)‎, ‎δ(g) and γ(g)‎ ‎be the minimum degree‎, ‎maximum degree and‎ ‎domination number of a graph g=(v(g)‎,‎e(g))‎, ‎respectively‎. ‎a partition of v(g)‎, ‎all of whose classes are dominating sets in g‎, ‎is called a domatic partition of g‎. ‎the maximum number of classes of‎ ‎a domatic partition of g is called the domatic number of g‎, ‎denoted d(g)‎. ‎it is well known that‎ ‎d(g)≤δ(g)‎+‎1‎, ‎d(g)γ(g)≤|v(g)| cite{ch}‎, ‎and |v(g)|≤(δ(g)‎+‎1)γ(g) cite{berge}‎. ‎in this paper‎, ‎we investigate the graphs g for which‎ ‎all the above inequalities become simultaneously equalities‎.