Online Social Choice and Welfare Seminar: Oihane Galo, Tuesday 21 October
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Marcus Pivato
Oct 15, 2025, 7:01:09 AMOct 15
to social-choice-a...@googlegroups.com, com...@duke.edu
[with apologies for cross-posting]
Dear all,
The next presentation in the Online Social Choice and Welfare Seminar will be next Tuesday (21 October). Here are the details.
Time: 9AM GMT (5AM Toronto/Montréal, 6AM Rio de Janeiro, 10AM London, 11AM Barcelona, 12PM Istanbul, 2:30PM New Delhi, 6PM Tokyo/Seoul, 8PM Sydney, 10PM Auckland)
Speaker: Oihane Galo (Universitat de Barcelona)
Title: "Anonymity and strategy-proofness on a domain of single-peaked and single-dipped preferences"
Abstract: We analyze the problem of locating a public facility on a line in a society where agents have single-peaked or single-dipped preferences. We consider the domain analyzed in Alcalde-Unzu et al. (2024), where the type of preference of each agent is public information, but the location of her peak/dip as well as the rest of the preference are unknown. We characterize all strategy-proof and type-anonymous rules on this domain. Building on existing results, we provide a two-step characterization: first, the median between the peaks and a collection of fixed locations is computed (Moulin, 1980), resulting in either a single alternative or a pair of contiguous alternatives. If the outcome of the median is a pair, we apply a “double-quota majority method" in the second step to choose between the alternatives in the pair (Moulin, 1983). We also show the additional restrictions implied by type-anonymity on the strategy-proof rules characterized by Alcalde-Unzu et al. (2024). Finally, we show the equivalence of the two characterizations.
Dear all,
The next presentation in the Online Social Choice and Welfare Seminar will be next Tuesday (21 October). Here are the details.
Time: 9AM GMT (5AM Toronto/Montréal, 6AM Rio de Janeiro, 10AM London, 11AM Barcelona, 12PM Istanbul, 2:30PM New Delhi, 6PM Tokyo/Seoul, 8PM Sydney, 10PM Auckland)
Speaker: Oihane Galo (Universitat de Barcelona)
Title: "Anonymity and strategy-proofness on a domain of single-peaked and single-dipped preferences"
Abstract: We analyze the problem of locating a public facility on a line in a society where agents have single-peaked or single-dipped preferences. We consider the domain analyzed in Alcalde-Unzu et al. (2024), where the type of preference of each agent is public information, but the location of her peak/dip as well as the rest of the preference are unknown. We characterize all strategy-proof and type-anonymous rules on this domain. Building on existing results, we provide a two-step characterization: first, the median between the peaks and a collection of fixed locations is computed (Moulin, 1980), resulting in either a single alternative or a pair of contiguous alternatives. If the outcome of the median is a pair, we apply a “double-quota majority method" in the second step to choose between the alternatives in the pair (Moulin, 1983). We also show the additional restrictions implied by type-anonymity on the strategy-proof rules characterized by Alcalde-Unzu et al. (2024). Finally, we show the equivalence of the two characterizations.
(Working paper available here.)
To obtain the Zoom link, please subscribe to the Seminar Mailing List, or contact one of the organisers.
Reminder: On the seminar website you can find the video recordings, slides and supplementary materials for all past presentations, as well as information about future presentations.
--
Marcus Pivato
Centre d'Économie de la Sorbonne
Centre d'Économie de la Sorbonne
Université Paris 1 Panthéon-Sorbonne
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