Algorithms for enumerating and counting D2CS of some graphs

A D2CS of a graph G is a set $S \subseteq V(G)$ with $diam(G[S]) \leq 2$. We study the problem of counting and enumerating D2CS of a graph. First we give an explicit formula for the number of D2CS in a complete k-ary tree, Fibonacci tree, binary Fibonacci tree and the binomial tree. Next we give an algorithm for enumerating and counting D2CS of a graph. We then give a linear time algorithm for finding all maximal D2CS in a strongly chordal graph.