Combinatorial search
Information Processing Letters
The Average-Case Complexity of Determining the Majority
SIAM Journal on Computing
ACM Transactions on Algorithms (TALG)
How to Play the Majority Game with Liars
AAIM '07 Proceedings of the 3rd international conference on Algorithmic Aspects in Information and Management
Randomized strategies for the plurality problem
Discrete Applied Mathematics
Average-case analysis of some plurality algorithms
ACM Transactions on Algorithms (TALG)
Oblivious and adaptive strategies for the majority and plurality problems
COCOON'05 Proceedings of the 11th annual international conference on Computing and Combinatorics
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The plurality problem is a game between two participants: Paul and Carole. We are given n balls, each of them is colored with one out of c colors. At any step of the game, Paul chooses two balls and asks whether they are of the same color, whereupon Carole answers yes or no. The game ends when Paul either produces a ball a of the plurality color (meaning that the number of balls colored like a exceeds those of the other colors), or when Paul states that there is no plurality. How many questions Lc(n) does Paul have to ask in the worst case?For c = 2, the problem is equivalent to the well-known majority problem which has already been solved (Combinatorica 11 (1991) 383-387). In this paper we show that 3 ⌊n/2⌋-2 ≤ L3(n) ≤ ⌊5n/3⌋ - 2. Moreover, for any c ≤ n, we show that surprisingly the naive algorithm for the plurality problem is asymptotically optimal.