Factorisation of generalised theta functions. I.
Factorization of point configurations, cyclic covers, and conformal blocks
We describe a relation between the invariants of ordered points in projective -space and of points contained in a union of two linear subspaces. This yields an attaching map for GIT quotients parameterizing point configurations in these spaces, and we show that it respects the Segre product of the natural GIT polarizations. Associated to a configuration supported on a rational normal curve is a cyclic cover, and we show that if the branch points are weighted by the GIT linearization and the rational...
Famiglie di curve sulle superfici algebriche
Families of algebraic curves with nodes
Families of curves and alterations
In this article it is shown that any family of curves can be altered into a semi-stable family. This implies that if is an excellent scheme of dimension at most 2 and is a separated integral scheme of finite type over , then can be altered into a regular scheme. This result is stronger then the results of [ Smoothness, semi-stability and alterations to appear in Publ. Math. IHES]. In addition we deal with situations where a finite group acts.
Families of Curves on Surfaces.
Families of Curves with Nodes on K-3 Surfaces.
Families of elliptic curves with genus 2 covers of degree 2.
We study genus 2 covers of relative elliptic curves over an arbitrary base in which 2 is invertible. Particular emphasis lies on the case that the covering degree is 2. We show that the data in the "basic construction" of genus 2 covers of relative elliptic curves determine the cover in a unique way (up to isomorphism).A classical theorem says that a genus 2 cover of an elliptic curve of degree 2 over a field of characteristic ≠ 2 is birational to a product of two elliptic curves over the projective...
Families of Mumford curves
Families of quintic surfaces and curves
Familles de revêtements de la droite projective
Fibrés de rang 2 sur une courbe, fibré déterminant et fonctions thêta
Fibrés de rang deux sur une courbe, fibré déterminant et fonctions thêta. II
Fibrés déterminants, déterminants régularisés et mesures sur les espaces de modules des courbes complexes
Fragmented deformations of primitive multiple curves
A primitive multiple curve is a Cohen-Macaulay irreducible projective curve Y that can be locally embedded in a smooth surface, and such that Y red is smooth. We study the deformations of Y to curves with smooth irreducible components, when the number of components is maximal (it is then the multiplicity n of Y). We are particularly interested in deformations to n disjoint smooth irreducible components, which are called fragmented deformations. We describe them completely. We give also a characterization...
Galois Covers and the Hilbert-Grunwald Property
Our main result combines three topics: it contains a Grunwald-Wang type conclusion, a version of Hilbert’s irreducibility theorem and a -adic form à la Harbater, but with good reduction, of the Regular Inverse Galois Problem. As a consequence we obtain a statement that questions the RIGP over . The general strategy is to study and exploit the good reduction of certain twisted models of the covers and of the associated moduli spaces.
Galois groups of fields of definition of solvable branched coverings
Gaussian maps and multiplication maps on certain projective varieties
Genera of curves varying in a family
General stable bundles arising as normal bundles of projective curves.