Strategy-Proof Preference Aggregation and the Anonymity-Neutrality Tradeoff

50 Pages Posted: 1 May 2023

See all articles by Stergios Athanasoglou

Stergios Athanasoglou

Università degli Studi di Milano-Bicocca - Department of Economics, Management and Statistics (DEMS); Università degli Studi di Milano-Bicocca - Center for European Studies (CefES)

Somouaoga Bonkoungou

University of Lausanne - Faculty of Business and Economics (HEC Lausanne)

Lars Ehlers

University of Montreal - Département de Sciences Economiques and CIREQ

Multiple version iconThere are 2 versions of this paper

Date Written: April 28, 2023

Abstract

Consider a setting in which individual strict preferences need to be aggregated into a social strict preference relation. For two alternatives and an odd number of agents, it follows from May’s Theorem that the majority aggregation rule is the only one satisfying anonymity, neutrality, and strategy-proofness (SP). For more than two alternatives, anonymity and neutrality are incompatible in many instances and we explore this tradeoff for strategy-proof rules. The notion of SP that we employ is Kemeny-SP (K- SP), which is based on the Kemeny distance between social orderings and strengthens previously used concepts in an intuitive manner. Dropping anonymity and keeping neutrality, we identify and analyze the first known nontrivial family of K-SP rules, namely semi-dictator rules. For two agents, semi-dictator rules are characterized by local unanimity, neutrality, and K-SP. For an arbitrary number of agents, we generalize semi-dictator rules to allow for committees and show that they retain their desirable properties. Dropping neutrality and keeping anonymity, we establish possibility results for three alternatives. We provide a computer-aided solution to the existence of a locally unanimous, anonymous, and K-SP rule for two agents and four alternatives. Finally, we show that there is no K-SP and anonymous rule which always chooses one of the agents’ preferences.

Keywords: Preference aggregation, strategy-proofness, anonymity, neutrality, Kemeny distance, semi-dictator rule

JEL Classification: D71, C70

Suggested Citation

Athanasoglou, Stergios and Bonkoungou, Somouaoga and Ehlers, Lars, Strategy-Proof Preference Aggregation and the Anonymity-Neutrality Tradeoff (April 28, 2023). University of Milan Bicocca Department of Economics, Management and Statistics Working Paper No. 519, Available at SSRN: https://ssrn.com/abstract=4431515

Stergios Athanasoglou (Contact Author)

Università degli Studi di Milano-Bicocca - Department of Economics, Management and Statistics (DEMS) ( email )

Piazza dell'Ateneo Nuovo, 1
Milano, 20126
Italy

Università degli Studi di Milano-Bicocca - Center for European Studies (CefES)

U6 Building
Viale Piero e Alberto Pirelli, 22
Milano, 20126
Italy

Somouaoga Bonkoungou

University of Lausanne - Faculty of Business and Economics (HEC Lausanne) ( email )

Switzerland

Lars Ehlers

University of Montreal - Département de Sciences Economiques and CIREQ ( email )

C.P. 6128, succursale Centre-Ville
Montreal, Quebec H3C 3J7
Canada

Do you have negative results from your research you’d like to share?

Paper statistics

Downloads
29
Abstract Views
113
PlumX Metrics