Economic Theory Bulletin

, Volume 6, Issue 1, pp 1–13 | Cite as

On the ultrafilter representation of coalitionally strategy-proof social choice functions

  • Surekha Rao
  • Achille Basile
  • K. P. S. Bhaskara Rao
Research Article


By means of a simple new characterization of ultrafilters, we elementarily prove, in the case of finitely many alternatives and arbitrarily large societies, that every coalitionally strategy-proof social choice function with at least three alternatives in its range is given by an ultrafilter. This provides an alternate and simple proof of results in Mihara (Soc Choice Welf 17:393–402, 2000). In case there are only two alternatives in the range of a coalitionally strategy-proof social choice function, we describe its structure, supplementing the work of Barberà et al. (Int J Game Theory 41:791–808, 2012).


Social choice functions Coalitional strategy proofness Gibbard–Satterthwaite theorem Ultrafilters 

Mathematics Subject Classification


JEL Classification



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Copyright information

© Society for the Advancement of Economic Theory 2017

Authors and Affiliations

  • Surekha Rao
    • 1
  • Achille Basile
    • 2
  • K. P. S. Bhaskara Rao
    • 3
  1. 1.School of Business and EconomicsIndiana University NorthwestGaryUSA
  2. 2.Dipartimento di Scienze Economiche e StatisticheUniversità Federico IINaplesItaly
  3. 3.Department of Computer Information SystemsIndiana University NorthwestGaryUSA

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