Projective 7-folds with positive defect

Antonio Lanteri; Daniele Struppa

Displaying similar documents to “Projective 7-folds with positive defect”

On the class of some projective varieties.

Edoardo Ballico, Marina Bertolini, Cristina Turrini (1997)

Collectanea Mathematica

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Some inequalities between the class and the degree of a smooth complex projective manifold are given. Application to the case of low sectional genus are supplied.

Subsheaves of the cotangent bundle

Paolo Cascini (2006)

Open Mathematics

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For any smooth projective variety, we study a birational invariant, defined by Campana which depends on the Kodaira dimension of the subsheaves of the cotangent bundle of the variety and its exterior powers. We provide new bounds for a related invariant in any dimension and in particular we show that it is equal to the Kodaira dimension of the variety, in dimension up to 4, if this is not negative.

On the dimension of the adjoint linear system for threefolds

M. C. Beltrametti, A. J. Sommese (1995)

Annali della Scuola Normale Superiore di Pisa - Classe di Scienze

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Seshadri positive submanifolds of polarized manifolds

Lucian Bădescu, Mauro Beltrametti (2013)

Open Mathematics

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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

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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.

Ample vector bundles with zero loci having a bielliptic curve section.

Antonio Lanteri, Hidetoshi Maeda (2003)

Collectanea Mathematica

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On projective degenerations of Veronese spaces

Edoardo Ballico (1996)

Banach Center Publications

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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...

Varieties with $P_{3} (X) = 4$ and $q (X) =$ dim $(X)$

Jungkai Alfred Chen, Christopher D. Hacon (2004)

Annali della Scuola Normale Superiore di Pisa - Classe di Scienze

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Algebraic Legendrian varieties

Jarosław Buczyński

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Real Legendrian subvarieties are classical objects of differential geometry and classical mechanics and they have been studied since antiquity (see [Arn74], [Sła91] and references therein). However, complex Legendrian subvarieties are much more rigid and have more exceptional properties. The most remarkable case is the Legendrian subvarieties of projective space; prior to the author's research only few smooth examples of these were known (see [Bry82], [LM07]). Strong restrictions on...