SMS scnews item created by Anna Romanov at Sat 29 Feb 2020 1127
Type: Seminar
Distribution: World
Expiry: 28 Feb 2021
Calendar1: 6 Mar 2020 1500-1700
CalTitle1: Cliff - Beilinson-Drinfeld Grassmannian and fusion
Calendar2: 13 Mar 2020 1500-1700
CalTitle2: Cliff - Beilinson-Drinfeld Grassmannian and fusion
Auth: romanova@203.54.33.225 (arom8272) in SMS-WASM

# Informal Friday Seminar: Cliff -- Beilinson-Drinfeld Grassmannian and fusion

Last semester we have seen the basics of the geometric Satake equivalence, which gives a
geometric realization of representations of a reductive algebraic group in terms of
perverse sheaves on the affine Grassmannian. However, the symmetry of the convolution
product was stated and not explained. This turns out to be a significant issue that was
solved by Drinfeld in the 80s, and not explained to anyone for about twenty years.

I will explain the key ideas behind Drinfeld’s construction. The key point is to
"globalize" the affine Grassmannian, which first involves interpreting the affine
Grassmannian as a moduli space of "ways of changing a G-bundle on a curve a point". Then
nearby cycles come to the rescue!


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