We study strategy-proof rules for choosing between two alternatives. We consider the full preference domain which allows for indifference. In this framework, for strategy proof rules, ontoness does not imply efficiency. We weaken the requirement of efficiency to ontoness and characterizes the...

Call a mechanism that associates each profile of preferences over candidates to an ambiguous act an Ambiguous Social Function (ASCF). This paper studies the strategy-proofness of ASCFs. We find that an ASCF is unanimous and strategyproof if and only if there exists a nonempty subset of voters,...

In many experiments, the Nash equilibrium concept seems not to predict well. One reason may be that players have non-selfish preferences over outcomes. As a consequence, even when they are told what the material payoffs of the game are, mutual knowledge of preferences may not be satisfied. We...