TY - JOUR
T1 - Robustness among multiwinner voting rules
AU - Bredereck, Robert
AU - Faliszewski, Piotr
AU - Kaczmarczyk, Andrzej
AU - Niedermeier, Rolf
AU - Skowron, Piotr
AU - Talmon, Nimrod
N1 - Funding Information:
We are grateful to the anonymous reviewers of SAGT 2017 and Artificial Intelligence for their useful comments. Robert Bredereck was partially supported by the DFG fellowship BR 5207/2 . Piotr Faliszewski was supported by the National Science Centre , Poland, under project 2016/21/B/ST6/01509 . Piotr Faliszewski's visit to TU Berlin was supported by a Friedrich Wilhelm Bessel Award from the Alexander von Humboldt Foundation . Andrzej Kaczmarczyk was supported by the DFG project AFFA ( BR 5207/1 and NI 369/15 ). Piotr Skowron was supported by a Humboldt Research Fellowship for Postdoctoral Researchers ( Alexander von Humboldt Foundation , Bonn) while staying at TU Berlin. Nimrod Talmon was supported by an I-CORE ALGO fellowship and by the Israel Science Foundation (ISF; Grant No. 630/19 ).
Funding Information:
We are grateful to the anonymous reviewers of SAGT 2017 and Artificial Intelligence for their useful comments. Robert Bredereck was partially supported by the DFG fellowship BR 5207/2. Piotr Faliszewski was supported by the National Science Centre, Poland, under project 2016/21/B/ST6/01509. Piotr Faliszewski's visit to TU Berlin was supported by a Friedrich Wilhelm Bessel Award from the Alexander von Humboldt Foundation. Andrzej Kaczmarczyk was supported by the DFG project AFFA (BR 5207/1 and NI 369/15). Piotr Skowron was supported by a Humboldt Research Fellowship for Postdoctoral Researchers (Alexander von Humboldt Foundation, Bonn) while staying at TU Berlin. Nimrod Talmon was supported by an I-CORE ALGO fellowship and by the Israel Science Foundation (ISF; Grant No. 630/19).
Publisher Copyright:
© 2020 Elsevier B.V.
PY - 2021/1/1
Y1 - 2021/1/1
N2 - We investigate how robust the results of committee elections are with respect 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 might be replaced, or (2) it is possible that the whole committee will be replaced. We also show that the problem of computing the smallest number of swaps that lead to changing the election outcome is typically NP-hard, but there are natural FPT algorithms. Finally, for a number of rules we assess experimentally the average number of random swaps necessary to change the election result.
AB - We investigate how robust the results of committee elections are with respect 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 might be replaced, or (2) it is possible that the whole committee will be replaced. We also show that the problem of computing the smallest number of swaps that lead to changing the election outcome is typically NP-hard, but there are natural FPT algorithms. Finally, for a number of rules we assess experimentally the average number of random swaps necessary to change the election result.
KW - Committee scoring rules
KW - Computational complexity
KW - Computational social choice
KW - Copeland
KW - Parameterized complexity
KW - Robustness level
KW - Robustness radius
KW - STV
KW - Winner determination
UR - http://www.scopus.com/inward/record.url?scp=85095684255&partnerID=8YFLogxK
U2 - 10.1016/j.artint.2020.103403
DO - 10.1016/j.artint.2020.103403
M3 - Article
AN - SCOPUS:85095684255
VL - 290
JO - Artificial Intelligence
JF - Artificial Intelligence
SN - 0004-3702
M1 - 103403
ER -