Definite arithmetische Gruppen.
Degeneration of the Kummer sequence in characteristic
We study a deformation of the Kummer sequence to the radicial sequence over an -algebra, which is somewhat dual for the deformation of the Artin-Schreier sequence to the radicial sequence, studied by Saidi. We also discuss some relations between our sequences and the embedding of a finite flat commutative group scheme into a connected smooth affine commutative group schemes, constructed by Grothendieck.
Degree three cohomological invariants of semisimple groups
We study the degree 3 cohomological invariants with coefficients in of a semisimple group over an arbitrary field. A list of all invariants of adjoint groups of inner type is given.
Del Pezzo surfaces of degree four
Die Relationenfaktorgruppen von Stickelberger-Elementen und Kreiszahlen.
Die Struktur der absoluten Galoisgruppe über dem Körper R (t).
Dividing rational points on abelian varieties of CM-type
Divisible subgroups of Brauer groups and trace forms of central simple algebras.