Hi, I have written a small piece of code which computes a 2k-1 multiplicative spanner (k is an integer parameter) of undirected weighted graphs. This spanner is simply a subgraph of an input graph which preserves shortest path distances up to a 2k-1 factor, that is the shortest path from u to v in the spanner is at most 2k-1 times the shortest path from u to v in the original graph. The main benefit is that there is always a 2k-1 spanner with O(n^{1+1/k}) edges. The algorithm is due to Althoefer, Das, Dobkin, Joseph and Soares. It is a simple generalization of Kruskal's algorithm (thus I used Kruskal's algorithm as a template). While not the fastest possible, it is simple and elegant. Is there any place where I could upload my code for interested people to review and comment? Best, Dimitris