Recovering non-monotonicity problems of voting rules

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dc.contributor.authorKeskin, Umut
dc.contributor.authorSanver, M. Remzi
dc.contributor.authorTosunlu, H. Berkay
dc.date.accessioned2024-07-18T20:40:36Z
dc.date.available2024-07-18T20:40:36Z
dc.date.issued2021
dc.departmentİstanbul Bilgi Üniversitesien_US
dc.description.abstractA social choice rule (SCR) is monotonic if raising a single alternative in voters' preferences while leaving the rankings otherwise unchanged is never detrimental to the prospects for winning of the raised alternative. Monotonicity is rather weak but well-known to discriminate against scoring elimination rules, such as plurality with a run off and single transferable vote. We define the minimal monotonic extension of an SCR as its unique monotonic supercorrespondence that is minimal with respect to set inclusion. After showing the existence of the concept, we characterize, for every non-monotonic SCR, the alternatives that its minimal monotonic extension must contain. As minimal monotonic extensions can entail coarse SCRs, we address the possibility of refining them without violating monotonicity provided that this refinement does not diverge from the original SCR more than the divergence prescribed by the minimal monotonic extension itself. We call these refinements monotonic adjustments and identify conditions over SCRs that ensure unique monotonic adjustments that are minimal with respect to set inclusion. As an application of our general findings, we consider plurality with a runoff, characterize its minimal monotonic extension as well as its (unique) minimal monotonic adjustment. Interestingly, this adjustment is not coarser than plurality with a runoff itself, hence we suggest it as a monotonic substitute to plurality with a runoff.en_US
dc.description.sponsorshipLAMSADE internal project programme; [ANR-14-CE24-0007-01 CoCoRICo-CoDec]; [IDEX ANR-10-IDEX-0001-02 PSL* MIFID]en_US
dc.description.sponsorshipOur work is partly supported by the projects ANR-14-CE24-0007-01 CoCoRICo-CoDec and IDEX ANR-10-IDEX-0001-02 PSL* MIFID, as well as the LAMSADE internal project programme. The main findings of this paper were discovered when H. Berkay Tosunlu was a masters student in economics at I stanbul Bilgi University. We thank Jerome Lang, Vincent Merlin, Herve Moulin and participants of the Dagstuhl Seminar 19381 on Application-Oriented Computational Social Choice for useful comments and discussions. The paper extensively benefited from the thoughtful comments of two anonymous reviewers and the anonymous associate editor to whom we are grateful.en_US
dc.identifier.doi10.1007/s00355-020-01272-0
dc.identifier.endpage141en_US
dc.identifier.issn0176-1714
dc.identifier.issn1432-217X
dc.identifier.issue1en_US
dc.identifier.scopus2-s2.0-85087761925en_US
dc.identifier.scopusqualityQ1en_US
dc.identifier.startpage125en_US
dc.identifier.urihttps://doi.org/10.1007/s00355-020-01272-0
dc.identifier.urihttps://hdl.handle.net/11411/7131
dc.identifier.volume56en_US
dc.identifier.wosWOS:000548194000001en_US
dc.identifier.wosqualityQ4en_US
dc.indekslendigikaynakWeb of Scienceen_US
dc.indekslendigikaynakScopusen_US
dc.language.isoenen_US
dc.publisherSpringeren_US
dc.relation.ispartofSocial Choice and Welfareen_US
dc.relation.publicationcategoryMakale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanıen_US
dc.rightsinfo:eu-repo/semantics/openAccessen_US
dc.subjectImplementationen_US
dc.subjectParadoxesen_US
dc.titleRecovering non-monotonicity problems of voting rules
dc.typeArticle

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