A Lower Bound of 1+f for Truthful Scheduling Mechanisms

We study the mechanism design version of the unrelated machines scheduling problem, which is at the core of Algorithmic Game Theory and was first proposed and studied in a seminal paper of Nisan and Ronen. We give an improved lower bound of 1+φ≈2.618 on the approximation ratio of deterministic truthful mechanisms for the makespan. The proof is based on a recursive preprocessing argument which yields a strictly increasing series of new lower bounds for each fixed number of machines n≥4.