4 papers · 1 filter
Minimal rational curves on complete symmetric varieties
Michel Brion, Shin-young Kim, Nicolas Perrin
We describe the families of minimal rational curves on any complete symmetric variety, and the corresponding varieties of minimal rational tangents (VMRT). In particular, we prove…
The inverse Galois problem for connected algebraic groups
Michel Brion, Stefan Schröer
We show that each connected group scheme of finite type over an arbitrary ground field is isomorphic to the component of the identity inside the automorphism group scheme of some p…
Equivariantly normal varieties for diagonalizable group actions
Michel Brion
Given a finite group scheme over a field and a -variety , we obtain a criterion for to be -normal in the sense of \cite{Br24}. When is diagonalizable, we descr…
Actions of finite group schemes on curves
Michel Brion
Every action of a finite group scheme on a variety admits a projective equivariant model, but not necessarily a normal one. As a remedy, we introduce and explore the notion of…