Rank aggregation methods for the Web
Proceedings of the 10th international conference on World Wide Web
Algorithm Design
Parameterized Complexity Theory (Texts in Theoretical Computer Science. An EATCS Series)
Parameterized Complexity Theory (Texts in Theoretical Computer Science. An EATCS Series)
The complexity of Kemeny elections
Theoretical Computer Science
Proceedings of the thirty-ninth annual ACM symposium on Theory of computing
Aggregating inconsistent information: Ranking and clustering
Journal of the ACM (JACM)
A computational study of the Kemeny rule for preference aggregation
AAAI'04 Proceedings of the 19th national conference on Artifical intelligence
Computing slater rankings using similarities among candidates
AAAI'06 Proceedings of the 21st national conference on Artificial intelligence - Volume 1
Improved bounds for computing Kemeny rankings
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
Deterministic algorithms for rank aggregation and other ranking and clustering problems
WAOA'07 Proceedings of the 5th international conference on Approximation and online algorithms
Parameterized Complexity
Parameterized complexity of candidate control in elections and related digraph problems
Theoretical Computer Science
Comparing multiagent systems research in combinatorial auctions and voting
Annals of Mathematics and Artificial Intelligence
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The computation of Kemeny rankings is central to many applications in the context of rank aggregation. Unfortunately, the problem is NP-hard. We show that the Kemeny score (and a corresponding Kemeny ranking) of an election can be computed efficiently whenever the average pairwise distance between two input votes is not too large. In other words, Kemeny Score is fixed-parameter tractable with respect to the parameter "average pairwise Kendall-Tau distance da". We describe a fixed-parameter algorithm with running time 16[da] · poly. Moreover, we extend our studies to the parameters "maximum range" and "average range" of positions a candidate takes in the input votes. Whereas Kemeny Score remains fixed-parameter tractable with respect to the parameter "maximum range", it becomes NP-complete in case of an average range value of two. This excludes fixed-parameter tractability with respect to the parameter "average range" unless P=NP.