2 citations · 4 across the 8 of their papers we have counts for
4 papers · 1 filter
Hom schemes for algebraic groups
Sean Cotner
In SGA3, Demazure and Grothendieck showed that if and are smooth affine group schemes over a scheme and is reductive, then the functor of -homomorphism …
Springer isomorphisms over a general base scheme
Sean Cotner
We establish the existence of Springer isomorphisms for reductive group schemes over general base schemes. For this, we first study centralizers of fiberwise regular sections of re…
Lefschetz theorems in flat cohomology and applications
Sean Cotner, Bogdan Zavyalov
We prove a version of the Lefschetz hyperplane theorem for fppf cohomology with coefficients in any finite commutative group scheme over the ground field. As consequences, we estab…
Centralizers of sections of a reductive group scheme
Sean Cotner
This paper proves a number of flatness results for centralizers of sections of a reductive group scheme over a general base scheme. To this end, we establish relative versions of t…