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Approximation and Hardness of Shift-Bribery [article]

Piotr Faliszewski, Pasin Manurangsi, Krzysztof Sornat
2019 arXiv   pre-print
We give the first polynomial-time approximation scheme for the Shift-Bribery problem for the case of positional scoring rules, and for the Copeland rule we show strong inapproximability results.  ...  In the Shift-Bribery problem we are given an election, a preferred candidate, and the costs of shifting this preferred candidate up the voters' preference orders.  ...  Pasin Manurangsi was supported by NSF Awards CCF-1813188 and CCF-1815434.  ... 
arXiv:1908.10562v1 fatcat:nhvtvn5qvbar7lanbhhjvd6vky

Approximation and Hardness of Shift-Bribery

Piotr Faliszewski, Pasin Manurangsi, Krzysztof Sornat
2019 PROCEEDINGS OF THE THIRTIETH AAAI CONFERENCE ON ARTIFICIAL INTELLIGENCE AND THE TWENTY-EIGHTH INNOVATIVE APPLICATIONS OF ARTIFICIAL INTELLIGENCE CONFERENCE  
In the SHIFT-BRIBERY problem we are given an election, a preferred candidate, and the costs of shifting this preferred candidate up the voters' preference orders.  ...  We give the first polynomial-time approximation scheme for the case of positional scoring rules, and for the Copeland rule we show strong inapproximability results.  ...  Pasin Manurangsi was supported by NSF Awards CCF-1813188 and CCF-1815434.  ... 
doi:10.1609/aaai.v33i01.33011901 fatcat:aussuir5ifckvhx6y54f2sisly

Prices matter for the parameterized complexity of shift bribery

Robert Bredereck, Jiehua Chen, Piotr Faliszewski, André Nichterlein, Rolf Niedermeier
2016 Information and Computation  
When we parameterize SHIFT BRIBERY by the number of affected voters, then for each of our voting rules (Borda, Maximin, Copeland) the problem is W[2]-hard.  ...  We study the parameterized computational complexity of SHIFT BRIBERY with respect to a number of parameters (pertaining to the nature of the solution sought and the size of the election) and several classes  ...  COPELAND SHIFT BRIBERY parameterized by the budget is W[2]-hard for arbitrary, sortable, and all-ornothing prices, and is W[1]-hard for convex and unit prices.  ... 
doi:10.1016/j.ic.2016.08.003 fatcat:mnylzn5ncrbytptacgls57u55a

Complexity of Shift Bribery in Committee Elections

Robert Bredereck, Piotr Faliszewski, Rolf Niedermeier, Nimrod Talmon
2016 PROCEEDINGS OF THE THIRTIETH AAAI CONFERENCE ON ARTIFICIAL INTELLIGENCE AND THE TWENTY-EIGHTH INNOVATIVE APPLICATIONS OF ARTIFICIAL INTELLIGENCE CONFERENCE  
(and hard to approximate) in the multiwinner ones.  ...  We focus on the SNTV, Bloc, k-Borda, and Chamberlin-Courant rules, as well as on approximate variants of the Chamberlin-Courant rule, since the original rule is NP-hard to compute.  ...  Parameterized by the number s of unit shifts, k-Borda SHIFT BRIBERY is W[1]-hard. Chamberlin-Courant and Its Variants We now move on to the CC rules and their approximate variants.  ... 
doi:10.1609/aaai.v30i1.10132 fatcat:5eyqipxshbanblge3ozxrn3foi

Large-Scale Election Campaigns: Combinatorial Shift Bribery

Robert Bredereck, Piotr Faliszewski, Rolf Niedermeier, Nimrod Talmon
2016 The Journal of Artificial Intelligence Research  
We show that, in general, the combinatorial variant of the problem is highly intractable; specifically, NP-hard, hard in the parameterized sense, and hard to approximate.  ...  We study the complexity of a combinatorial variant of the Shift Bribery problem in elections.  ...  Approximation Algorithms We now explore the possibility of finding approximate solutions for Combinatorial Shift Bribery.  ... 
doi:10.1613/jair.4927 fatcat:gcwvxkudgrgnvju24k67jgocxi

Approximation Algorithms for Campaign Management [article]

Edith Elkind, Piotr Faliszewski
2010 arXiv   pre-print
We describe a 2-approximation algorithm for this problem for a large class of electoral systems known as scoring rules.  ...  We also give approximation algorithms for our problem for two Condorcet-consistent rules, namely, the Copeland rule and maximin.  ...  Piotr Faliszewski is supported in part by AGH University of Science and Technology Grant no. 11.11.120.865, by Polish Ministry of Science and Higher Education grant N-N206-378637, by Foundation for Polish  ... 
arXiv:1004.0334v3 fatcat:kmcnu7emrbf7fo52l2wuts4ffm

Campaign Management Under Approval-Driven Voting Rules

Ildiko Schlotter, Piotr Faliszewski, Edith Elkind
2015 Algorithmica  
We show that finding an optimal campaign management strategy of the first type is easy for both Bucklin and Fallback.  ...  Approval-like voting rules, such as Sincere-Strategy Preference-Based Approval voting (SP-AV), the Bucklin rule (an adaptive variant of k-Approval voting), and the Fallback rule (an adaptive variant of  ...  Since the hardness result for Fallback-SUPPORT BRIBERY holds even if all bribery costs are either 0 or +∞, it follows that this problem does not admit an approximation algorithm with a bounded approximation  ... 
doi:10.1007/s00453-015-0064-0 fatcat:6kwupridp5h2fbzq24zqxquu7q

Swap Bribery

Edith Elkind, Piotr Faliszewski, Arkadii Slinko
2009 Social Science Research Network  
We prove complexity results for this model, which we call swap bribery, for a broad class of voting rules, including variants of approval and kapproval, Borda, Copeland, and maximin.  ...  Each swap may have a different price; the price of a bribery is the sum of the prices of all swaps that it involves.  ...  Piotr Faliszewski is supported by AGH University of Science and Technology grant no. 11.11.120.777.  ... 
doi:10.2139/ssrn.1422183 fatcat:xwj4jzy2pfc7raaddfjgvrlmb4

Swap Bribery [chapter]

Edith Elkind, Piotr Faliszewski, Arkadii Slinko
2009 Lecture Notes in Computer Science  
We prove complexity results for this model, which we call swap bribery, for a broad class of election systems, including variants of approval and k-approval, Borda, Copeland, and maximin.  ...  Each swap may have a different price; the price of a bribery is the sum of the prices of all swaps that it involves.  ...  Piotr Faliszewski is supported by AGH University of Science and Technology grant no. 11.11.120.777.  ... 
doi:10.1007/978-3-642-04645-2_27 fatcat:nrdfhgj4nbfxphereytz3vycgy

Complexity of Shift Bribery in Committee Elections [article]

Robert Bredereck, Piotr Faliszewski, Rolf Niedermeier, Nimrod Talmon
2018 arXiv   pre-print
We show that SHIFT BRIBERY tends to be harder in the multiwinner setting than in the single-winner one by showing settings where SHIFT BRIBERY is easy in the single-winner cases, but is hard (and hard  ...  Of course, shifting comes at a price (depending on the voter and on the extent of the shift) and one must not exceed the given budget.  ...  Acknowledgments The authors were supported in part by the DFG project PAWS (NI 369/10) and the NCN project DEC-2012/06/M/ST1/00358.  ... 
arXiv:1601.01492v2 fatcat:orpx4lpx3raodcawrs2674eyaa

Prices Matter for the Parameterized Complexity of Shift Bribery [article]

Robert Bredereck, Jiehua Chen, Piotr Faliszewski, André Nichterlein, Rolf Niedermeier
2016 arXiv   pre-print
When we parameterize Shift Bribery by the number of affected voters, then for each of our voting rules (Borda, Maximin, Copeland) the problem is W[2]-hard.  ...  We study the parameterized computational complexity of Shift Bribery with respect to a number of parameters (pertaining to the nature of the solution sought and the size of the election) and several classes  ...  Acknowledgments We are grateful to the anonymous referees of AAAI 2014 and of Information and Computation that helped us to significantly improve the paper.  ... 
arXiv:1502.01253v2 fatcat:rrbrcjswhjgvpmqr5vrk3f6tiu

Complexity of Shift Bribery in Hare, Coombs, Baldwin, and Nanson Elections

Cynthia Maushagen, Marc Neveling, Jörg Rothe, Ann-Kathrin Selker
2018 International Symposium on Artificial Intelligence and Mathematics  
We show that shift bribery is intractable for the voting systems of Hare, Coombs, Baldwin, and Nanson.  ...  Even though shift bribery also possesses a number of hardness results (Elkind, Faliszewski, and Slinko 2009) , it has also been shown to allow exact and approximate polynomial-time algorithms in a number  ...  K Baldwin and Nanson We now show NP-hardness of shift bribery for Baldwin and Nanson elections.  ... 
dblp:conf/isaim/MaushagenNRS18 fatcat:hbhqs3odnndebfwlu53w3feboe

Campaign Management under Approval-Driven Voting Rules [article]

Ildikó Schlotter and Piotr Faliszewski and Edith Elkind
2015 arXiv   pre-print
We show that finding an optimal campaign management strategy of the first type is easy for both Bucklin and Fallback.  ...  Approval-like voting rules, such as Sincere-Strategy Preference-Based Approval voting (SP-AV), the Bucklin rule (an adaptive variant of k-Approval voting), and the Fallback rule (an adaptive variant of  ...  Piotr Faliszewski was supported in part by AGH University of Technology Grant no. 11.11.230.124, by Polish Ministry of Science and Higher Education grant N-N206-378637, and by Foundation for Polish Science's  ... 
arXiv:1501.00387v1 fatcat:r3b4dre4rzg6pa7w3jsqplxgdu

Parameterized Algorithmics for Computational Social Choice: Nine Research Challenges [article]

Robert Bredereck and Jiehua Chen and Piotr Faliszewski and Jiong Guo and Rolf Niedermeier and Gerhard J. Woeginger
2014 arXiv   pre-print
hard problems.  ...  Computational Social Choice is an interdisciplinary research area involving Economics, Political Science, and Social Science on the one side, and Mathematics and Computer Science (including Artificial  ...  We thank Britta Dorn, Dominikus Krüger, Jörg Rothe, Lena Schend, Arkardii Slinko, Nimrod Talmon, and an anonymous referee for their constructive feedback on previous versions of the manuscript.  ... 
arXiv:1407.2143v1 fatcat:l7hupjhho5h7jdwes7wxxpmlby

Parameterized algorithmics for computational social choice: Nine research challenges

Robert Bredereck, Jiehua Chen, Piotr Faliszewski, Jiong Guo, Rolf Niedermeier, Gerhard J. Woeginger
2014 Tsinghua Science and Technology  
hard problems.  ...  Computational Social Choice is an interdisciplinary research area involving Economics, Political Science, and Social Science on the one side, and Mathematics and Computer Science (including Artificial  ...  We thank Britta Dorn, Dominikus Krüger, Jörg Rothe, Lena Schend, Arkardii Slinko, Nimrod Talmon, and an anonymous referee for their constructive feedback on previous versions of the manuscript.  ... 
doi:10.1109/tst.2014.6867518 fatcat:hbftzfbi65fq7agrno3nubfz3e
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