English

An Improved Upper Bound on the Threshold Bias of the Oriented-cycle game

Combinatorics 2025-03-24 v1

Abstract

We study the bb-biased Oriented-cycle game where two players, OMaker and OBreaker, take turns directing the edges of KnK_n (the complete graph on nn vertices). In each round, OMaker directs one previously undirected edge followed by OBreaker directing between one and bb previously undirected edges. The game ends once all edges have been directed, and OMaker wins if and only if the resulting tournament contains a directed cycle. Bollob\'as and Szab\'o asked the following question: what is the largest value of the bias bb for which OMaker has a winning strategy? Ben-Eliezer, Krivelevich and Sudakov proved that OMaker has a winning strategy for bn/22b \leq n/2 - 2. In the other direction, Clemens and Liebenau proved that OBreaker has a winning strategy for b5n/6+2b \geq 5n/6+2. Inspired by their approach, we propose a significantly stronger strategy for OBreaker which we prove to be winning for b0.7845n+O(1)b \geq 0.7845n + O(1).

Keywords

Cite

@article{arxiv.2503.16770,
  title  = {An Improved Upper Bound on the Threshold Bias of the Oriented-cycle game},
  author = {Anita Liebenau and Abdallah Saffidine and Jeffrey Yang},
  journal= {arXiv preprint arXiv:2503.16770},
  year   = {2025}
}

Comments

15 pages, 1 figure