On Strategy-proofness and Symmetric Single-Peakedness

Abstract

We characterize the class of strategy-proof social choice functions on the domain of symmetric single-peaked preferences. This class is strictly larger than the set of generalized median voter schemes (the class of strategy-proof and tops-only social choice functions on the domain of single peaked preferences characterized by Moulin (1980)) since, under the domain of symmetric single-peaked preferences, generalized median voter schemes can be disturbed by discontinuity points and remain strategy-proof on the smaller domain. Our result identifies the specific nature of these discontinuities which allow to design non-onto social choice functions to deal with feasibility constraints.
Published as: On Strategy-Proofness and Symmetric Single-Peakedness in Games and Economic Behavior , Vol. 72, No. 2, 467--484, January, 2011