Collusion-resistant, incentive-compatible feedback payments

Abstract

Online reputation mechanisms need honest feedback to function effectively. Self-interested agents report the truth only when explicit rewards offset the potential gains obtained from lying. Feedback payment schemes (monetary rewardsfor submitted feedback) can make truth-telling rational based on the correlation between the reports of different buyers. In this paper we investigate incentive-compatible payment mechanisms that are also resistant to collusion: groups of agents cannot collude on a lying strategy without suffering monetary losses. We analyze several scenarios, where, for example, some or all of the agents collude. For each scenario we investigate both existential and implementation problems. Throughout the paper we use automated mechanism design to compute the best possible mechanism for a given setting.