Wednesday February 10, 4:00pm-5:10pm
Padelford
C-401
Pre-Seminar 3:30pm-3:55pm in PDL C-401
ABSTRACT
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Pre-seminar is on Wednesday in Padelford C-401 at 3:30pm-3:55pm.
Given a permutation (or more generally an element in a finite reflection group) $w$, one can define a hyperplane arrangement $\mathcal{A}_w\subseteq\mathbb{R}^n$ called the inversion arrangement. On the symmetric group (or any finite reflection group), one can define a partial order known as Bruhat order. Hultman showed that the number of regions $\mathcal{A}_w$ cuts $\mathbb{R}^n$ into is always at most the number of elements less than or equal to $w$ in Bruhat order, and gave a condition on the Bruhat graph (a graph related to Bruhat order) for when equality occurs. |
Sara Billey, Combinatorics Seminar, Mathematics Department, University of Washington |
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