Grothendieck--Serre in the quasi--split unramified case
Speaker: Kestutis Cesnavicius (U. Paris Sud)

Time: 15h15, Friday, April 2, 2021

Join Zoom Meeting:

ZOOM ID:466 356 2952


Session Chair: Prof. Phung Ho Hai (VAST Hanoi)

Abstract: The Grothendieck--Serre conjecture predicts that every generically trivial torsor under a reductive group scheme G over a regular local ring R is trivial. We settle it in the case when G is quasi-split and R is unramified. To overcome obstacles that have so far kept the mixed characteristic case out of reach, we adapt Artin's construction of "good neighborhoods" to the setting where the base is a discrete valuation ring, build equivariant compactifications of tori over higher dimensional bases, and study the geometry of the affine Grassmannian in bad characteristics.

For general information of the AGEA seminar, please check out


or the mirror site



New Scientiffic Publications