Computing the dilation of edge-augmented graphs in metric spaces

Let G=(V,E) be an undirected graph with n vertices embedded in a metric space. We consider the problem of adding a shortcut edge in G that minimizes the dilation of the resulting graph. The fastest algorithm to date for this problem has O(n^4) running time and uses O(n^2) space. We show how to improve the running time to O(n^3logn) while maintaining quadratic space requirement. In fact, our algorithm not only determines the best shortcut but computes the dilation of [email protected]?{(u,v)} for every pair of distinct vertices u and v.