Universal bounds on the torsion of elliptic curves
Universal covering spaces and fundamental groups in algebraic geometry as schemes
In topology, the notions of the fundamental group and the universal cover are closely intertwined. By importing usual notions from topology into the algebraic and arithmetic setting, we construct a fundamental group family from a universal cover, both of which are schemes. A geometric fiber of the fundamental group family (as a topological group) is canonically the étale fundamental group. The constructions apply to all connected quasicompact quasiseparated schemes. With different methods and hypotheses,...
Universal cycle classes
Universal extensions and -adic periods of elliptic curves
Universal transitivity of simple and 2-simple prehomogeneous vector spaces
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
Universal Weil Divisors.
Universelle Eigenschaften der Wittschen Vektoren und der Einseinheitenalgebra einer Potenzreihenalgebra in einer Veränderlichen.
Universell-endliche Erweiterungen analytischer Algebren.
Unobstructedness and dimension of families of Gorenstein algebras.
The goal of this paper is to develop tools to study maximal families of Gorenstein quotients A of a polynomial ring R. We prove a very general theorem on deformations of the homogeneous coordinate ring of a scheme Proj(A) which is defined as the degeneracy locus of a regular section of the dual of some sheaf M of rank r supported on say an arithmetically Cohen-Macaulay subscheme Proj(B) of Proj(R). Under certain conditions (notably; M maximally Cohen-Macaulay and ∧r M ≈ KB(t) a twist of the canonical...
Unramified Brauer group of the moduli spaces of PGLr(ℂ)-bundles over curves
Let X be an irreducible smooth complex projective curve of genus g, with g ≥ 2. Let N be a connected component of the moduli space of semistable principal PGLr (ℂ)-bundles over X; it is a normal unirational complex projective variety. We prove that the Brauer group of a desingularization of N is trivial.
Unramified cohomology and rationality problems.
Unramified cohomology of alternating groups
We prove vanishing results for the unramified stable cohomology of alternating groups.
Unramified cohomology of classifying varieties for classical simply connected groups
Unramified nonspecial real space curves having many real branches and few ovals.
Let C ⊆ Pn be an unramified nonspecial real space curve having many real branches and few ovals. We show that C is a rational normal curve if n is even, and that C is an M-curve having no ovals if n is odd.
Unramified Skolem problems and unramified arithmetic Bertini theorems in positive characteristic.
Unstable hyperplane for Steiner bundles and multidimensional matrices.
Unstable vector bundles and linear systems on surfaces in characteristic p.
Unterbündel maximalen Grades von Vektorbündeln auf algebraischen Kurven.
Untersuchungen über das Flächennetz zweiter Ordnung.
Untersuchungen über die Theilwerthe der Jacobischen Thetafunctionen und die im Gauss'schen Nachlasse mitgetheilten Beziehungen derselben