English

Cyclic subsets of tournaments

Combinatorics 2025-08-06 v1

Abstract

Let GG be a Dirac graph, and let SS be a vertex subset of GG, chosen uniformly at random. How likely is the induced subgraph G[S]G[S] to be Hamiltonian? This question, proposed by Erd\H{o}s and Faudree in 1996, was recently resolved by Dragani\'c, Keevash and M\"uyesser, in the setting of graphs. In this paper, we study a similar question for tournaments -- if TT is a tournament of high minimum degree, how likely is it for a random induced subtournament of TT to be Hamiltonian? We prove an optimal bound on this probability, and extend the results to the regime where the subset is not sampled uniformly at random, but according to a pp-biased measure.

Keywords

Cite

@article{arxiv.2508.03634,
  title  = {Cyclic subsets of tournaments},
  author = {Zach Hunter and Teng Liu and Aleksa Milojević and Benny Sudakov},
  journal= {arXiv preprint arXiv:2508.03634},
  year   = {2025}
}

Comments

13 pages

R2 v1 2026-07-01T04:35:32.172Z