Speakers:  Kęstutis Česnavičius  (Université Paris-Saclay)

Title:  The affine Grassmannian as a presheaf quotient

Abstract: The affine Grassmannian of a reductive group G is usually defined as the étale sheafification of the quotient of the loop group LG by the positive loop subgroup. I will discuss various triviality results for G-torsors which imply that this sheafification is often not necessary.