TY - JOUR
T1 - Prices matter for the parameterized complexity of shift bribery
AU - Bredereck, Robert
AU - Chen, Jiehua
AU - Faliszewski, Piotr
AU - Nichterlein, André
AU - Niedermeier, Rolf
N1 - Funding Information:
Robert Bredereck was supported by the DFG project PAWS (NI 369/10). Jiehua Chen was partially supported by the Studienstiftung des Deutschen Volkes. Piotr Faliszewski was partially supported by the DFG project PAWS (NI 369/10) while staying at TU Berlin, and by AGH University grant 11.11.230.124 (statutory research) during the rest of the project.
Publisher Copyright:
© 2016 Elsevier Inc.
PY - 2016/12/1
Y1 - 2016/12/1
N2 - In the SHIFT BRIBERY problem, we are given an election, a preferred candidate p, and a budget. The goal is to ensure p's victory by shifting p higher in some voters’ preference orders. However, each such shift request comes at a price and we must not exceed the given budget. We study the parameterized computational complexity of SHIFT BRIBERY for a number of parameters and several classes of price functions: For the number of affected voters, SHIFT BRIBERY is W[2]-hard for Borda, Maximin, and Copeland. For the number of positions by which p is shifted in total, the problem is fixed-parameter tractable for Borda and Maximin, and is W[1]-hard for Copeland. For the budget, the results depend on the price function class. Finally, SHIFT BRIBERY tends to be tractable when parameterized by the number of voters, but the results for the number of candidates are more enigmatic.
AB - In the SHIFT BRIBERY problem, we are given an election, a preferred candidate p, and a budget. The goal is to ensure p's victory by shifting p higher in some voters’ preference orders. However, each such shift request comes at a price and we must not exceed the given budget. We study the parameterized computational complexity of SHIFT BRIBERY for a number of parameters and several classes of price functions: For the number of affected voters, SHIFT BRIBERY is W[2]-hard for Borda, Maximin, and Copeland. For the number of positions by which p is shifted in total, the problem is fixed-parameter tractable for Borda and Maximin, and is W[1]-hard for Copeland. For the budget, the results depend on the price function class. Finally, SHIFT BRIBERY tends to be tractable when parameterized by the number of voters, but the results for the number of candidates are more enigmatic.
KW - Computational social choice
KW - FPT approximation scheme
KW - Fixed-parameter tractability (FPT)
KW - Multivariate complexity analysis
KW - Voting and rank aggregation
KW - W-hardness
UR - http://www.scopus.com/inward/record.url?scp=85005990835&partnerID=8YFLogxK
U2 - 10.1016/j.ic.2016.08.003
DO - 10.1016/j.ic.2016.08.003
M3 - Article
AN - SCOPUS:85005990835
VL - 251
SP - 140
EP - 164
JO - Information and Computation
JF - Information and Computation
SN - 0890-5401
ER -