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arXiv · 2602.09863

Characterizing Large Clique Number in Tournaments

Logan Crew·Xinyue Fan·Hidde Koerts·Benjamin Moore·Sophie Spirkl
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Abstract

Aboulker, Aubian, Charbit, and Lopes (2023) defined the clique number of a tournament to be the minimum clique number of one of its backedge graphs. Here we show that if $T$ is a tournament of sufficiently large clique number, then $T$ contains a subtournament of large clique number from one of two simple families of tournaments. In particular, large clique number is always certified by a bounded-size set. This answers a question of Aboulker, Aubian, Charbit, and Lopes (2023), and gives new insight into a line of research initiated by Kim and Kim (2018) into unavoidable subtournaments in tournaments with large dichromatic number.

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Logan Crew, Xinyue Fan, Hidde Koerts, Benjamin Moore, Sophie Spirkl. 2026-02-10. Characterizing Large Clique Number in Tournaments. https://arxiv.org/abs/2602.09863

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