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Home » EGN Math-Physics seminar: Top heaviness and hard Lefschetz in combinatorics

Seminar

EGN Math-Physics seminar: Top heaviness and hard Lefschetz in combinatorics April 16, 2018 (01:30 PM PDT - 03:00 PM PDT)
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Location: MSRI: Simons Auditorium
Speaker(s) Geordie Williamson (University of Sydney)
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How many faces in each dimension can a simplicial polytope have? This question turns out to have a beautiful answer, which was conjectured by McMullen in 1971 and proved by Stanley and Billera-Lee in the 80s. It is natural to ask what one can say for other combinatorial structures. I will review several instances where hard Lefschetz provides the only known explanation of "top heaviness". Then I will focus on Bruhat intervals, where only pieces of the puzzle are understood.

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