Search
Search Results
-
A constructive approach to a conjecture by Voskresenskii
Voskresenskii conjectured that stably rational tori are rational. Klyachko proved this assertion for a wide class of tori by general principles. We...
-
On abstract representations of the groups of rational points of algebraic groups in positive characteristic
We analyze the structure of a large class of connected algebraic rings over an algebraically closed field of positive characteristic using...
-
Good reduction of algebraic groups and flag varieties
In 1983, Faltings proved that there are only finitely many abelian varieties over a number field of fixed dimension and with good reduction outside a...
-
Which algebraic groups are Picard varieties?
We show that every connected commutative algebraic group over an algebraically closed field of characteristic 0 is the Picard variety of some...
-
On the “Galois Closure” for Finite Morphisms
We give necessary and sufficient conditions for a finite flat morphism of schemes of characteristic Hurwitz stacks.p > 0 to be dominated by a torsor... -
Fundamental Groupoid Scheme
This article is an overview of the original construction by Nori of the fundamental group scheme as the Galois group of some Tannaka category EF(X)... -
The Coherent Cohomology Ring of an Algebraic Group
Let G be a group scheme of finite type over a field, and consider the cohomology ring H * ( G ) with coefficients in the structure sheaf. We show that H ...
-
Vector bundles over normal varieties trivialized by finite morphisms
Let Y be a normal and projective variety over an algebraically closed field k and V a vector bundle over Y . We prove that if there exist a k -scheme X ...
-
Extension of finite solvable torsors over a curve
Let R be a complete discrete valuation ring with fraction field K and with algebraically closed residue field of positive characteristic p . Let X be...
-
On the Geometry of Global Function Fields, the Riemann–Roch Theorem, and Finiteness Properties of S-Arithmetic Groups
In this survey I sketch Behr–Harder reduction theory for reductive groups over global functions fields and briefly describe its applicability in the... -
Remarks on the Isotriviality of Multiloop Algebras
For a given finite dimensional simple Lie algebra g over an algebraically closed field of characteristic 0, we establish the existence of a positive... -
Factorisation properties of group scheme actions
Let H be an algebraic group scheme over a field k acting on a commutative k -algebra A which is a unique factorisation domain. We show that, under...
-
Differential operators and automorphism schemes
The ring of global differential operators of a variety is in closed and deep relation with its automorphism scheme. This relation can be applied to...
-
Gersten conjecture for equivariant K-theory and applications
For a reductive group scheme G over a regular semi-local ring A , we prove the Gersten conjecture for the equivariant K -theory. As a consequence, we...
-
Foliations in Moduli Spaces of Abelian Varieties and Dimension of Leaves
In moduli spaces of abelian varieties and of p-divisible groups in characteristic p we have various foliations and statifications. In this paper we... -
Reduction of structure for torsors over semilocal rings
Let G be a reductive affine group scheme defined over a semilocal ring k . Assume that either G is semisimple or k is normal and noetherian. We show...
-
Effective technology and design teaching: getting it right in the classroom
Technology and design was added to the Northern Ireland curriculum in September 1992 and through it, teachers seek to address the need for pupils to...