The main result of this paper characterizes voting by committees. There are n voters and K objects. Voters must choose a subset of K. Voting by committees is defined by one monotone family of winning coalitions for each object; an object is chosen if it is supported by one of its winning...

The authors consider the allocation of goods in exchange economies with a finite number of agents who may have private information about their preferences. They characterize the set of allocation rules that are compatible with individual incentives or, in other words, the set of strategy-proof...