A taxonomy of non-dictatorial domains

• Main Authors: CHATTERJI, Shurojit, ZENG, Huaxia
• Format: text
• Language: English
• Published: Institutional Knowledge at Singapore Management University 2020
• Subjects: Strategy-proofness; invariance; path-connectedness; (semi)-single-peaked preference; (semi)-hybrid preference; Economic Theory; Taxation
• Online Access: https://ink.library.smu.edu.sg/soe_research/2408; https://ink.library.smu.edu.sg/context/soe_research/article/3407/viewcontent/model_201027_final_version_.pdf
• Institution: Singapore Management University

We provide an exhaustive classification of all preference domains that allow the design of unanimous social choice functions (henceforth, rules) that are non-dictatorial and strategy-proof. This taxonomy is based on a richness assumption and employs a simple property of two-voter rules called invariance. The preference domains that form the classification are semi-single-peaked domains (introduced by Chatterji et al. (2013)) and semi-hybrid domains (introduced here) which are two appropriate weakenings of the single-peaked domains, and which, more importantly, are shown to allow strategy-proof rules to depend on non-peak information of voters’ preferences. As a refinement of the classification, single-peaked domains and hybrid domains emerge as the only preference domains that force strategy-proof rules to be determined completely by the peaks of voters’ preferences. We also provide characterization results for strategy-proof rules on these domains.