Maximal Recursive Rule: A New Social Decision Scheme / 34
In social choice settings with strict preferences, random dictatorship rules were characterized by Gibbard  as the only randomized social choice functions that satisfy strategyproofness and ex post efficiency. In the more general domain with indifferences, RSD (random serial dictatorship) rules are the well-known and perhaps only known generalization of random dictatorship. We present a new generalization of random dictatorship for indifferences called Maximal Recursive (MR) rule as an alternative to RSD. We show that MR is polynomial-time computable, weakly strategyproof with respect to stochastic dominance, and, in some respects, outperforms RSD on efficiency.