-Fano threefolds of large Fano index. I.
In questo lavoro vengono costruite famiglie di 3-folds algebriche e non singolari di tipo generale tali che l'invariante sia il minimo possibile rispetto al genere geometrico , quando si suppone che il morfismo canonico sia birazionale. Per tali 3-folds vale la relazione lineare inoltre l'immagine del morfismo canonico é una varietà di Castelnuovo di .
Studying the connection between the title configuration and Kummer surfaces we write explicit quadratic equations for the latter. The main results are presented in Theorems 8 and 16.
Generalizing a result of Bombieri, Masser, and Zannier we show that on a curve in the algebraic torus which is not contained in any proper coset only finitely many points are close to an algebraic subgroup of codimension at least . The notion of close is defined using the Weil height. We also deduce some cardinality bounds and further finiteness statements.
In this paper we classify rank two Fano bundles on Fano manifolds satisfying . The classification is obtained via the computation of the nef and pseudoeffective cones of the projectivization , that allows us to obtain the cohomological invariants of and . As a by-product we discuss Fano bundles associated to congruences of lines, showing that their varieties of minimal rational tangents may have several linear components.