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Condorcet winning sets

Elkind, Edith; Lang, Jérôme; Saffidine, Abdallah (2015), Condorcet winning sets, Social Choice and Welfare, 44, 3, p. 493-517. 10.1007/s00355-014-0853-4

Type
Article accepté pour publication ou publié
Date
2015
Journal name
Social Choice and Welfare
Volume
44
Number
3
Publisher
Springer
Pages
493-517
Publication identifier
Metadata
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Author(s)
Elkind, Edith

Lang, Jérôme
Laboratoire d'analyse et modélisation de systèmes pour l'aide à la décision [LAMSADE]
Saffidine, Abdallah
Computer Science and Engineering [Sydney] [CSE]
Abstract (EN)
An alternative is said to be a Condorcet winner of an election if it is preferred to any other alternative by a majority of voters. While this is a very attractive solution concept, many elections do not have a Condorcet winner. In this paper, we propose a set-valued relaxation of this concept, which we call a Condorcet winning set: such sets consist of alternatives that collectively dominate any other alternative. We also consider a more general version of this concept, where instead of domination by a majority of voters we require domination by a given fraction θ of voters; we refer to such sets as θ-winning sets. We explore social choice-theoretic and algorithmic aspects of these solution concepts, both theoretically and empirically.
Subjects / Keywords
Condorcet winner; algorithm