” In particular, we prove that the problem is APX-hard even if there are only two different red costs, and give an approximation algorithm whose approximation ratio is at most $min {k,1+ln b,1+ln W}$, where $k$ is the number of distinct red costs, $b$ is the number of blue edges, and $W$ is the maximum ratio between red costs.
More:
[cs/0703019] The Stackelberg Minimum Spanning Tree Game
Tags: blue-edges, different-red, fractional, game, game_theory, maximum, network, number, the-maximum, the-number