Über die Glattheit von Quotientenabbildungen.
The goal of these lectures is to explain speaker’s results on uniqueness properties of spherical varieties. By a uniqueness property we mean the following. Consider some special class of spherical varieties. Define some combinatorial invariants for spherical varieties from this class. The problem is to determine whether this set of invariants specifies a spherical variety in this class uniquely (up to an isomorphism). We are interested in three classes: smooth affine varieties, general affine varieties,...
We denote by a field of characteristic zero satisfying . Let be a connected -split linear algebraic group acting on rationally by with a Zariski-dense -orbit . A prehomogeneous vector space ,X) is called “universally transitive” if the set of -rational points is a single