Displaying similar documents to “Some intrinsic and extrinsic characterizations of the projective space”

Multiple point Seshadri constants and the dimension of adjoint linear series

Oliver Küchle (1996)

Annales de l'institut Fourier

Similarity:

In this note multiple point Seshadri constants measuring the positivity of ample line bundles on complex projective varieties at a finite number of points are defined. A lower bound which is asymptotically optimal for a large number of points is proven for the constant at very general points. As an application estimates on the number of sections in adjoint linear systems are deduced.

On projective degenerations of Veronese spaces

Edoardo Ballico (1996)

Banach Center Publications

Similarity:

Here we give several examples of projective degenerations of subvarieties of ℙ t . The more important case considered here is the d-ple Veronese embedding of ℙ n ; we will show how to degenerate it to the union of d n n-dimensional linear subspaces of ℙ t ; t : = ( n + d ) / ( n ! d ! ) - 1 and the union of scrolls. Other cases considered in this paper are essentially projective bundles over important varieties. The key tool for the degenerations is a general method due to Moishezon. We will give elsewhere several applications to...

Seshadri positive submanifolds of polarized manifolds

Lucian Bădescu, Mauro Beltrametti (2013)

Open Mathematics

Similarity:

Let Y be a submanifold of dimension y of a polarized complex manifold (X, A) of dimension k ≥ 2, with 1 ≤ y ≤ k−1. We define and study two positivity conditions on Y in (X, A), called Seshadri A-bigness and (a stronger one) Seshadri A-ampleness. In this way we get a natural generalization of the theory initiated by Paoletti in [Paoletti R., Seshadri positive curves in a smooth projective 3-fold, Atti Accad. Naz. Lincei Cl. Sci. Fis. Mat. Natur. Rend. Lincei (9) Mat. Appl., 1996, 6(4),...

On the k-regularity of some proyective manifolds.

Alberto Alzati, Gian Mario Besana (1998)

Collectanea Mathematica

Similarity:

The conjecture on the (degree-codimension + 1) - regularity of projective varieties is proved for smooth linearly normal polarized varieties (X,L) with L very ample, for low values of Delta(X,L) = degree-codimension-1. Results concerning the projective normality of some classes of special varieties including scrolls over curves of genus 2 and quadric fibrations over elliptic curves, are proved.