Domain Of Single-peaked Preferences Research Articles

On obvious strategy-proofness and single-peakedness

We characterize the set of all obviously strategy-proof and onto social choice functions on the domain of single-peaked preferences. Since obvious strategy-proofness implies strategy-proofness, and the set of strategy-proof and onto social choice functions on this domain coincides with the class of generalized median voter schemes, we focus on this class. We identify a condition on generalized median voter schemes for which the following characterization holds. A generalized median voter scheme is obviously strategy-proof if and only if it satisfies the increasing intersection property. Our proof is constructive; for each generalized median voter scheme that satisfies the increasing intersection property we define an extensive game form that implements it in obviously dominant strategies.

The decomposition of strategy-proof random social choice functions on dichotomous domains

A feature of strategy-proof and efficient random social choice functions (RSCFs) defined over several important domains is that they are fixed probability distributions over deterministic strategy-proof and efficient social choice functions. We call such domains deterministic extreme point (DEP) domains. Examples of DEP domains are the domain of all strict preferences and the domain of single-peaked preferences. We show that the dichotomous domain introduced in Bogomolnaia et al. (2005) is not a DEP domain. We find a necessary condition for a strategy-proof RSCF to be written as a fixed probability distribution of deterministic strategy proof social choice functions. We show that this condition is compatible with efficiency. We also show that the condition is sufficient for decomposability in a special case.

Dynamically consistent voting rules

This paper studies preference aggregation in a dynamic choice context. Voters face menus of options in stages and the source of dynamics is that menus possibly get smaller across each stage. We call the family of stage voting rules “dynamic voting rules” and provide an axiomatic characterization, on the domain of single-peaked preferences, of dynamic voting rules that are strategy-proof and satisfy a second property, inspired from choice theory, which we call dynamic consistency.

A sufficient condition for the equivalence of strategy-proofness and nonmanipulability by preferences adjacent to the sincere one

I consider whether the agentsʼ reluctance to make a large lie is helpful for the rule designer to construct a nonmanipulable rule. For this purpose, I study an axiom, called AM-proofness, saying that manipulation cannot occur through preferences adjacent to the sincere one. Through examples, I give rationales for AM-proofness. My main result is a sufficient condition on a domain for the equivalence of AM-proofness and strategy-proofness. I show that the sufficient condition is satisfied by the universal domain and the domain of single-peaked preferences. Over such domains, all results about strategy-proofness can be restated with AM-proofness.

On strategy-proofness and symmetric single-peakedness

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.

Sprumont's characterization of the uniform rule when all single-peaked preferences are admissible

Sprumont (1991) has established that the only allocation rule for the division problem that is strategy-proof, efficient, and anonymous is the uniform rule when the domain is the set of all possible profiles of continuous single-peaked preferences. Sprumont's characterization of the uniform rule is shown to hold on any larger domain of single-peaked preferences.