Undominated VCG redistribution mechanisms

Many important problems in multiagent systems can be seen as resource allocation problems. For such problems, the well-known Vickrey-Clarke-Groves (VCG) mechanism is efficient, incentive compatible, individually rational, and does not incur a deficit. However, the VCG mechanism is not (strongly) budget balanced: generally, the agents’ payments will sum to more than 0. Very recently, several mechanisms have been proposed that redistribute a significant percentage of the VCG payments back to the agents while maintaining the other properties. This increases the agents’ utilities. One redistribution mechanism dominates another if it always redistributes at least as much to each agent (and sometimes more). In this paper, we provide a characterization of undominated redistribution mechanisms. We also propose several techniques that take a dominated redistribution mechanism as input, and produce as output another redistribution mechanism that dominates the original. One technique immediately produces an undominated redistribution mechanism that is not necessarily anonymous. Another technique preserves anonymity, and repeated application results in an undominated redistribution mechanism in the limit. We show experimentally that these techniques improve the known redistribution mechanisms.