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Friday, December 4, 2020

Friday, December 4, 2020 — 3:30 PM EST

Title: Partial orders on the symmetric group

Speaker: Oliver Pechenik Affiliation: University of Waterloo Zoom: Please email Emma Watson

Abstract:

The symmetric group of permutations is naturally a poset in at least 4 different ways, the (strong) Bruhat order and three flavors of weak order. Stanley showed in 1980 that the Bruhat order is Sperner, essentially meaning that the obvious large antichains are in fact the largest possible. The corresponding fact for weak orders was open until last year, when it was established by Gaetz and Gao.

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