Robustness Among Multiwinner Voting Rules

  • Robert Bredereck
  • Piotr Faliszewski
  • Andrzej Kaczmarczyk
  • Rolf Niedermeier
  • Piotr Skowron
  • Nimrod Talmon
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10504)

Abstract

We investigate how robust are results of committee elections to small changes in the input preference orders, depending on the voting rules used. We find that for typical rules the effect of making a single swap of adjacent candidates in a single preference order is either that (1) at most one committee member can be replaced, or (2) it is possible that the whole committee can be replaced. We also show that the problem of computing the smallest number of swaps that lead to changing the election outcome is typically \({\mathrm {NP}}\)-hard, but there are natural \({\mathrm {FPT}}\) algorithms. Finally, for a number of rules we assess experimentally the average number of random swaps necessary to change the election result.

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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Robert Bredereck
    • 1
  • Piotr Faliszewski
    • 2
  • Andrzej Kaczmarczyk
    • 3
  • Rolf Niedermeier
    • 3
  • Piotr Skowron
    • 3
  • Nimrod Talmon
    • 4
  1. 1.University of OxfordOxfordUK
  2. 2.AGH UniversityKrakowPoland
  3. 3.TU BerlinBerlinGermany
  4. 4.Weizmann Institute of ScienceRehovotIsrael

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