We consider voting rules on a multidimensional policy space for a continuum of voters with elliptic preferences. Assuming continuity, gamma -strategy-proofnessmeaning that coalitions of size smaller or equal to a small number gamma cannot manipulateand unanimity, we show that such rules are...

In this paper we axiomatically characterize two recursive procedures for defining a social group. The first procedure starts with the set of all individuals who are defined by everyone in the society as group members, while the starting point of the second procedure is the set of all individuals...