Truthful Mechanisms for Steiner Tree Problems

Consider an undirected graph G = (V, E) model for a communication network, where each edge is owned by a selfish agent, who reports the cost for offering the use of her edge. Note that each edge agent may misreport her own cost for the use of the edge for her own benefit. In such a noncooperative setting, we aim at designing an approximately truthful mechanism for establishing a Steiner tree, a minimum cost tree spanning over all the terminals. We present a truthful-in-expectation mechanism that achieves the approximation ratio ln 4 + ϵ ≈ 1.39, which matches the current best algorithmic ratio for STP.