English

A plurality problem with three colors and query size three

Combinatorics 2017-08-22 v1 Discrete Mathematics

Abstract

The Plurality problem - introduced by Aigner \cite{A2004} - has many variants. In this article we deal with the following version: suppose we are given nn balls, each of them colored by one of three colors. A \textit{plurality ball} is one such that its color class is strictly larger than any other color class. Questioner wants to find a plurality ball as soon as possible or state there is no, by asking triplets (or kk-sets, in general), while Adversary partition the triplets into color classes as an answer for the queries and wants to postpone the possibility of determining a plurality ball (or stating there is no). We denote by Ap(n,3)A_p(n,3) the largest number of queries needed to ask if both play optimally (and Questioner asks triplets). We provide an almost precise result in case of even nn by proving that for n4n \ge 4 even we have 34n2Ap(n,3)34n12,\frac{3}{4}n-2 \le A_p(n,3) \le \frac{3}{4}n-\frac{1}{2}, and for n3n \ge 3 odd we have 34nO(logn)Ap(n,3)34n12.\frac{3}{4}n-O(\log n) \le A_p(n,3) \le \frac{3}{4}n-\frac{1}{2}. We also prove some bounds on the number of queries needed to ask for larger kk.

Keywords

Cite

@article{arxiv.1708.05864,
  title  = {A plurality problem with three colors and query size three},
  author = {Dániel Gerbner and Dániel Lenger and Máté Vizer},
  journal= {arXiv preprint arXiv:1708.05864},
  year   = {2017}
}

Comments

29 pages

R2 v1 2026-06-22T21:18:37.123Z