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Main Authors: Liebenau, Anita, Saffidine, Abdallah, Yang, Jeffrey
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2503.16770
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author Liebenau, Anita
Saffidine, Abdallah
Yang, Jeffrey
author_facet Liebenau, Anita
Saffidine, Abdallah
Yang, Jeffrey
contents We study the $b$-biased Oriented-cycle game where two players, OMaker and OBreaker, take turns directing the edges of $K_n$ (the complete graph on $n$ vertices). In each round, OMaker directs one previously undirected edge followed by OBreaker directing between one and $b$ 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. Bollobás and Szabó asked the following question: what is the largest value of the bias $b$ for which OMaker has a winning strategy? Ben-Eliezer, Krivelevich and Sudakov proved that OMaker has a winning strategy for $b \leq n/2 - 2$. In the other direction, Clemens and Liebenau proved that OBreaker has a winning strategy for $b \geq 5n/6+2$. Inspired by their approach, we propose a significantly stronger strategy for OBreaker which we prove to be winning for $b \geq 0.7845n + O(1)$.
format Preprint
id arxiv_https___arxiv_org_abs_2503_16770
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle An Improved Upper Bound on the Threshold Bias of the Oriented-cycle game
Liebenau, Anita
Saffidine, Abdallah
Yang, Jeffrey
Combinatorics
05C20, 05C57
We study the $b$-biased Oriented-cycle game where two players, OMaker and OBreaker, take turns directing the edges of $K_n$ (the complete graph on $n$ vertices). In each round, OMaker directs one previously undirected edge followed by OBreaker directing between one and $b$ 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. Bollobás and Szabó asked the following question: what is the largest value of the bias $b$ for which OMaker has a winning strategy? Ben-Eliezer, Krivelevich and Sudakov proved that OMaker has a winning strategy for $b \leq n/2 - 2$. In the other direction, Clemens and Liebenau proved that OBreaker has a winning strategy for $b \geq 5n/6+2$. Inspired by their approach, we propose a significantly stronger strategy for OBreaker which we prove to be winning for $b \geq 0.7845n + O(1)$.
title An Improved Upper Bound on the Threshold Bias of the Oriented-cycle game
topic Combinatorics
05C20, 05C57
url https://arxiv.org/abs/2503.16770