We define different concepts of group strategy-proofness for social choice functions. We discuss the connections between the defined concepts under different assumptions on their domains of definition. We characterize the social choice functions that satisfy each one of them and whose ranges...

A decision-maker exhibits preference for flexibility if he always prefers any set of alternatives to its subsets, even when two of them contain the same best element. Desire for flexibility can be explained as the consequence of the agent’s uncertainty along a two-stage process, where he must...

We provide characterizations of the set of outcomes that can be achieved by agenda manipulation for two prominent sequential voting procedures, the amendment and the successive procedure. Tournaments and super-majority voting with arbitrary quota q are special cases of the general sequential...

A social choice function may or may not satisfy a desirable property depending on its domain of definition. For the same reason, different conditions may be equivalent for functions defined on some domains, while not in other cases. Understanding the role of domains is therefore a crucial issue...

When members of a voting body exhibit single peaked preferences, pair-wise majority voting equilibria (Condorcet winners) always exist. Moreover, they coincide with the median(s) of the votersʼ most preferred alternatives. This important fact is known as the median voter result. Variants of it...

This paper surveys the literature on strategy-proofness from a historical perspective. While I discuss the connections with other works on incentives in mechanism design, the main emphasis is on social choice models. This article has been prepared for the Handbook of Social Choice and Welfare,...

I present a general theorem on preference aggregation. This theorem implies, as corollaries, Arrow's Impossibility Theorem, Wilson's extension of Arrow's to non-Paretian aggregation rules, the Gibbard-Satterthwaite Theorem and Sen's result on the Impossibility of a Paretian Liberal. The theorem...

Barberà and Coelho (2006) documented six screening rules associated with the rule of k names that are used by different institutions around the world. Here, we study whether these screening rules satisfy stability. A set is said to be a weak Condorcet set à la Gehrlein (1985) if no candidate...