Network flows: theory, algorithms, and applications
Network flows: theory, algorithms, and applications
Voting for movies: the anatomy of a recommender system
Proceedings of the third annual conference on Autonomous Agents
Rank aggregation methods for the Web
Proceedings of the 10th international conference on World Wide Web
The new FIFA rules are hard: complexity aspects of sports competitions
Discrete Applied Mathematics
Computers and Intractability: A Guide to the Theory of NP-Completeness
Computers and Intractability: A Guide to the Theory of NP-Completeness
Introduction to Algorithms
A heuristic technique for multi-agent planning
Annals of Mathematics and Artificial Intelligence
Journal of Computer and System Sciences
When are elections with few candidates hard to manipulate?
Journal of the ACM (JACM)
Anyone but him: The complexity of precluding an alternative
Artificial Intelligence
On the robustness of preference aggregation in noisy environments
Proceedings of the 6th international joint conference on Autonomous agents and multiagent systems
A sufficient condition for voting rules to be frequently manipulable
Proceedings of the 9th ACM conference on Electronic commerce
Generalized scoring rules and the frequency of coalitional manipulability
Proceedings of the 9th ACM conference on Electronic commerce
Proceedings of the 7th international joint conference on Autonomous agents and multiagent systems - Volume 2
Proceedings of the 7th international joint conference on Autonomous agents and multiagent systems - Volume 3
Elections Can be Manipulated Often
FOCS '08 Proceedings of the 2008 49th Annual IEEE Symposium on Foundations of Computer Science
Nonexistence of voting rules that are usually hard to manipulate
AAAI'06 Proceedings of the 21st national conference on Artificial intelligence - Volume 1
The complexity of bribery in elections
AAAI'06 Proceedings of the 21st national conference on Artificial intelligence - Volume 1
Llull and copeland voting broadly resist bribery and control
AAAI'07 Proceedings of the 22nd national conference on Artificial intelligence - Volume 1
Junta distributions and the average-case complexity of manipulating elections
Journal of Artificial Intelligence Research
Complexity of strategic behavior in multi-winner elections
Journal of Artificial Intelligence Research
An axiomatic approach to personalized ranking systems
IJCAI'07 Proceedings of the 20th international joint conference on Artifical intelligence
Hybrid elections broaden complexity-theoretic resistance to control
IJCAI'07 Proceedings of the 20th international joint conference on Artifical intelligence
Universal voting protocol tweaks to make manipulation hard
IJCAI'03 Proceedings of the 18th international joint conference on Artificial intelligence
Small coalitions cannot manipulate voting
FC'05 Proceedings of the 9th international conference on Financial Cryptography and Data Security
FCT'07 Proceedings of the 16th international conference on Fundamentals of Computation Theory
How hard is bribery in elections?
Journal of Artificial Intelligence Research
Theoretical Computer Science
SAGT '09 Proceedings of the 2nd International Symposium on Algorithmic Game Theory
Manipulation of copeland elections
Proceedings of the 9th International Conference on Autonomous Agents and Multiagent Systems: volume 1 - Volume 1
On the role of distances in defining voting rules
Proceedings of the 9th International Conference on Autonomous Agents and Multiagent Systems: volume 1 - Volume 1
Using complexity to protect elections
Communications of the ACM
Towards a dichotomy for the Possible Winner problem in elections based on scoring rules
Journal of Computer and System Sciences
Control complexity in fallback voting
CATS '10 Proceedings of the Sixteenth Symposium on Computing: the Australasian Theory - Volume 109
Comparing multiagent systems research in combinatorial auctions and voting
Annals of Mathematics and Artificial Intelligence
Information and Computation
Approximation algorithms for campaign management
WINE'10 Proceedings of the 6th international conference on Internet and network economics
On making a distinguished vertex minimum degree by vertex deletion
SOFSEM'11 Proceedings of the 37th international conference on Current trends in theory and practice of computer science
The complexity of manipulative attacks in nearly single-peaked electorates
Proceedings of the 13th Conference on Theoretical Aspects of Rationality and Knowledge
Multimode control attacks on elections
Journal of Artificial Intelligence Research
Possible winners when new alternatives join: new results coming up!
The 10th International Conference on Autonomous Agents and Multiagent Systems - Volume 2
The complexity of voter partition in Bucklin and fallback voting: solving three open problems
The 10th International Conference on Autonomous Agents and Multiagent Systems - Volume 2
Computational complexity of two variants of the possible winner problem
The 10th International Conference on Autonomous Agents and Multiagent Systems - Volume 2
How hard is it to bribe the judges? a study of the complexity of bribery in judgment aggregation
ADT'11 Proceedings of the Second international conference on Algorithmic decision theory
Bribery in path-disruption games
ADT'11 Proceedings of the Second international conference on Algorithmic decision theory
Is computational complexity a barrier to manipulation?
Annals of Mathematics and Artificial Intelligence
Winner determination in voting trees with incomplete preferences and weighted votes
Autonomous Agents and Multi-Agent Systems
Cloning in elections: finding the possible winners
Journal of Artificial Intelligence Research
Studies in computational aspects of voting: open problems of downey and fellows
The Multivariate Algorithmic Revolution and Beyond
Strategic considerations in the design of committees
Proceedings of the 2013 international conference on Autonomous agents and multi-agent systems
Control in the presence of manipulators: cooperative and competitive cases
IJCAI'13 Proceedings of the Twenty-Third international joint conference on Artificial Intelligence
Control complexity of schulze voting
IJCAI'13 Proceedings of the Twenty-Third international joint conference on Artificial Intelligence
Normalized Range Voting Broadly Resists Control
Theory of Computing Systems
Discrete Applied Mathematics
The complexity of manipulative attacks in nearly single-peaked electorates
Artificial Intelligence
On the computation of fully proportional representation
Journal of Artificial Intelligence Research
Annals of Mathematics and Artificial Intelligence
A smooth transition from powerlessness to absolute power
Journal of Artificial Intelligence Research
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Control and bribery are settings in which an external agent seeks to influence the outcome of an election. Constructive control of elections refers to attempts by an agent to, via such actions as addition/deletion/partition of candidates or voters, ensure that a given candidate wins. Destructive control refers to attempts by an agent to, via the same actions, preclude a given candidate's victory. An election system in which an agent can sometimes affect the result and it can be determined in polynomial time on which inputs the agent can succeed is said to be vulnerable to the given type of control. An election system in which an agent can sometimes affect the result, yet in which it is NP-hard to recognize the inputs on which the agent can succeed, is said to be resistant to the given type of control. Aside from election systems with an NP-hard winner problem, the only systems previously known to be resistant to all the standard control types were highly artificial election systems created by hybridization. This paper studies a parameterized version of Copeland voting, denoted by Copelandα, where the parameter α is a rational number between 0 and 1 that specifies how ties are valued in the pairwise comparisons of candidates. In every previously studied constructive or destructive control scenario, we determine which of resistance or vulnerability holds for Copelandα for each rational α, 0 ≤ α ≤ 1. In particular, we prove that Copeland0.5, the system commonly referred to as "Copeland voting," provides full resistance to constructive control, and we prove the same for Copelandα, for all rational α, 0 0 and Copeland1 (interestingly, Copeland1 is an election system developed by the thirteenth-century mystic Llull) are resistant to all standard types of constructive control other than one variant of addition of candidates. Moreover,we show that for each rational α, 0 ≤ α ≤ 1, Copelandα voting is fully resistant to bribery attacks, and we establish fixed-parameter tractability of bounded-case control for Copelandα. We also study Copelandα elections under more flexible models such as microbribery and extended control, we integrate the potential irrationality of voter preferences into many of our results, and we prove our results in both the unique-winner model and the nonunique-winner model. Our vulnerability results for microbribery are proven via a novel technique involving min-cost network flow.