Truthful Reputation Information in Electronic Markets without Independent Verification

Reputation mechanisms offer an efficient way of building the necessary level of trust in electronic markets. In the absence of independent verification authorities that can reveal the true outcome of a transaction, market designers have to insure that it is in the best interest of the trading agents to report the behavior in transactions truthfully. As opposed to side-payment schemes that correlate a present report with future reports submitted about the same agent, we present a mechanism that discovers (in equilibrium) the true outcome of a transaction by analyzing the two reports coming from the agents involved in the exchange. For two long-run rational agents, we show that it is possible to design such a mechanism that makes cooperation a stable equilibrium.