The Wiener number of powers of the Mycielskian

The Wiener number of a graph G is defined as 1 2 ∑ u,v∈V (G) d(u, v), d the distance function on G. The Wiener number has important applications in chemistry. We determine a formula for the Wiener number of an important graph family, namely, the Mycielskians μ(G) of graphs G. Using this, we show that for k ≥ 1, W (μ(S n)) ≤ W (μ(T k n )) ≤ W (μ(P k n )), where Sn, Tn and Pn denote a star, a general tree and a path on n vertices respectively. We also obtain Nordhaus-Gaddum type inequality for the Wiener number of μ(G).