Zobrazeno 1 - 10
of 51
pro vyhledávání: '"Sierra, José Carlos"'
Autor:
Sierra, José Carlos
Publikováno v:
Comptes Rendus. Mathématique, Vol 359, Iss 7, Pp 853-860 (2021)
Every morphism from $\mathbb{P}^n$ to $\mathbb{G}(k,m)$ is constant if $m, and nonconstant morphisms from $\mathbb{P}^n$ to $\mathbb{G}(k,n)$ rarely appear when $0. In this setting, Tango proved that a morphism from $\mathbb{P}^n$ to $\mathbb{G}(1,n)
Externí odkaz:
https://doaj.org/article/73b4091531f7489c9c895c39ac8a8950
We give an almost complete classification of non-big Ulrich vector bundles on fourfolds. This allows to classify them in the case of Picard rank one fourfolds, of Mukai fourfolds and in the case of Del Pezzo $n$-folds for $n \le 4$. We also classify
Externí odkaz:
http://arxiv.org/abs/2205.10143
On any smooth $n$-dimensional variety we give a pretty precise picture of rank $r$ Ulrich vector bundles with numerical dimension at most $\frac{n}{2}+r-1$. Also, we classify non-big Ulrich vector bundles on quadrics and on the Del Pezzo fourfold of
Externí odkaz:
http://arxiv.org/abs/2201.06019
We study geometrical properties of an Ulrich vector bundle $E$ of rank $r$ on a smooth $n$-dimensional variety $X \subseteq \mathbb P^N$. We characterize ampleness of $E$ and of $\det E$ in terms of the restriction to lines contained in $X$. We prove
Externí odkaz:
http://arxiv.org/abs/2105.05979
Autor:
Alzati, Alberto, Sierra, José Carlos
Publikováno v:
Int. Math. Res. Notices (2013)
Special birational transformations $\Phi:\p^r\da Z$ defined by quadric hypersurfaces are studied by means of the variety of lines $\mathcal L_z\subset\p^{r-1}$ passing through a general point $z\in Z$. Classification results are obtained when $Z$ is
Externí odkaz:
http://arxiv.org/abs/1302.5004
Autor:
Alzati, Alberto, Sierra, José Carlos
Extending some results of Crauder and Katz, and Ein and Shepherd-Barron on special Cremona transformations, we study birational transformations of the complex projective spaces onto prime Fano manifolds such that the base locus X of the transformatio
Externí odkaz:
http://arxiv.org/abs/1203.5690
Autor:
Sierra, José Carlos
We complete the classification of smooth surfaces swept out by a 1-dimensional family of plane curves that do not form a fibration. As a consequence, we characterize manifolds swept out by a 1-dimensional family of hypersurfaces that do not form a fi
Externí odkaz:
http://arxiv.org/abs/1203.0213
Autor:
Sierra, José Carlos
Publikováno v:
Math. Res. Lett. 18 (2011) 783--789
We present a slightly different formulation of Zak's theorem on tangencies as well as some applications. In particular, we obtain a better bound on the dimension of the dual variety of a manifold and we classify extremal and next-to-extremal cases wh
Externí odkaz:
http://arxiv.org/abs/1203.0208
Autor:
Sierra, José Carlos, Ugaglia, Luca
Extending a previous result of the authors, we classify globally generated vector bundles on projective spaces with first Chern class equal to three.
Comment: To appear in J. Pure Appl. Algebra
Comment: To appear in J. Pure Appl. Algebra
Externí odkaz:
http://arxiv.org/abs/1203.0185
Autor:
Alzati, Alberto, Sierra, José Carlos
We consider complex projective schemes $X\subset\Bbb{P}^{r}$ defined by quadratic equations and satisfying a technical hypothesis on the fibres of the rational map associated to the linear system of quadrics defining $X$. Our assumption is related to
Externí odkaz:
http://arxiv.org/abs/1006.5857