Tutte Colloquium -Sophie Spirkl-Cliques and colouring in tournaments

Friday, May 22, 2026 3:30 pm - 4:30 pm EDT (GMT -04:00)

Notice

I would consider it a kindness if attendees would wear masks. I will provide free masks for those who may need them.]

Speaker: Sophie Spirkl
Affiliation: University of Waterloo
Location: MC 5501

Abstract: A tournament is an orientation of a complete graph, and in terms of structural questions, tournaments are often a natural analogue of graphs. Neumann-Lara, in 1982, defined what it means to colour a tournament. Only recently, in 2023, Aboulker, Aubian, Charbit and Lopes defined what the clique number of a tournament is — but it is a bit more complicated than in graphs. What can we say about these parameters, from a structural and computational point of view? There are a few things to say, including a recent joint result with Logan Crew, Xinyue Fan, Hidde Koerts, and Ben Moore.

[Many of you know the severe consequences that a COVID infection has had for my family. I would consider it a kindness if attendees would wear masks. I will provide free masks for those who may need them.]