Resolutions of Richardson varieties, stable curves, and dual simplicial spheres

Allen Knutson (Cornell)

Fri Jan 28, 20:00-21:00 (starts in 17 hours)

Abstract: The combinatorics of a simple normal crossings divisor determines a "dual" simplicial complex. Kollár and Xu showed that when this divisor is anticanonical, the simplicial complex has the rational homology of a sphere. I'll construct two resolutions-of-singularities of Richardson varieties (a slight generalization of Schubert varieties), one using Bott-Samelson manifolds, the other (requiring no choices!) using circle-equivariant stable curves. In each case the dual simplicial complex is actually homeomorphic to a sphere.

algebraic geometry

Audience: researchers in the topic

Comments: The synchronous discussion for Allen Knutson’s talk is taking place not in zoom-chat, but at tinyurl.com/2022-01-28-ak (and will be deleted after ~3-7 days).


Stanford algebraic geometry seminar

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More seminar information (including slides and videos, when available): agstanford.com

Organizer: Ravi Vakil*
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