Note: Upper bounds on the Steiner diameter of a graph

• Authors: Patrick Ali;Peter Dankelmann;Simon Mukwembi
• Venue: Discrete Applied Mathematics
• Year: 2012

Let G be a connected graph of order p and S a nonempty set of vertices of G. Then the Steiner distance d(S) of S is the minimum size of a connected subgraph of G whose vertex set contains S. If n is an integer, 2@?n@?p, the Steiner n-diameter, diam"n(G), of G is the maximum Steiner distance of any n-subset of vertices of G. We give a bound on diam"n(G) for a graph G in terms of the order of G and the minimum degree of G. Our result implies a bound on the ordinary diameter by Erdos, Pach, Pollack and Tuza. We obtain improved bounds on diam"n(G) for K"3-free graphs and C"4-free graphs. Moreover, we construct graphs to show that the bounds are asymptotically best possible.