On the Hardness of Being Truthful

The central problem in computational mechanism design is the tension between incentive compatibility and computational ef ciency. We establish the rst significant approximability gap between algorithms that are both truthful and computationally-ef cient, and algorithms that only achieve one of these two desiderata. This is shown in the context of a novel mechanism design problem which we call the COMBINATORIAL PUBECT PROBLEM (CPPP). CPPP is an abstraction of many common mechanism design situations, ranging from elections of kibbutz committees to network design. Our result is actually made up of two complementary results – one in the communication-complexity model and one in the computational-complexity model. Both these hardness results heavily rely on a combinatorial characterization of truthful algorithms for our problem. Our computational-complexity result is one of the rst impossibility results connecting mechanism design to complexity theory; its novel proof technique involves a...

• Type: Conference
• Year: 2008
• Where: FOCS
• Authors: Christos H. Papadimitriou, Michael Schapira, Yaron Singer
• Keywords: Computational Mechanism Design, FOCS 2008, Mechanism Design, Mechanism Design Problem, Theoretical Computer Science