connected domination number of central trees

Let g = (v, e) be a graph. a subset s of v is called a dominating set of g if every vertex not in s is adjacent to some vertex in s. ##the domination number γ(g) of g is the minimum cardinality taken over all dominating sets of g. a dominating set s is called a connected dominating set if the induced subgraph < s > is connected. ##the minimum cardinality taken over all connected dominating sets of g is called the connected domination number of g and is denoted by γc (g). ##in this paper, we study the connected domination number of central trees. indeed, we obtain some tight bounds for the connected domination number of a central trees c(t) in terms of some invariants of the graph t.## also we characterize the connected domination number of the central of some families of trees