Mostrando ítems 1-20 de 20

• #### A note on a conjecture of Xiao ﻿

(1998)
Artículo
Acceso abierto
• #### A note on a question of Fujita and a conjecture of Xiao ﻿

(1998)
Artículo
Acceso abierto
• #### Experiència pràctica de comunicació de Matemàtiques a la ciutadania i a secundària – 2a fase ﻿

(Universitat Politècnica de Catalunya. Institut de Ciències de l'Educació, 2013-02-08)
Texto en actas de congreso / Comunicación de congreso
Acceso restringido por decisión del autor
El projecte implementa experiències pràctiques dels estudis universitaris de matemàtiques (grau, llicenciatura i màsters) en l'àmbit de la docència i la divulgació científica. La finalitat divulgativa pretén fomentar ...
• #### Extension of maps defined on many fibres ﻿

(1997)
Artículo
Acceso abierto
Let S be a fibred surface. We prove that the existence of morphisms from non countably many fibres to curves implies, up to base change, the existence of a rational map from S to another surface fibred over the same base ...
• #### Generalized Clifford-Severi inequality and the volume of irregular varieties ﻿

(2013-03-02)
Report de recerca
Acceso restringido por decisión del autor
We give a sharp lower bound for the selfintersection of a nef li ne bundle L on an irregular variety X in terms of its continuous global sections and the Albanese dim ension of X, which we call the Generalized Clifford-Severi ...
• #### Generalized Clifford-Severi inequality and the volume of irregular varieties ﻿

(2015-02-15)
Artículo
Acceso abierto
We give a sharp lower bound for the self-intersection of a nef line bundle L on an irregular variety X in terms of its continuous global sections and the Albanese dimension of X, which we call the generalized Clifford-Severi ...
• #### Numerical Bounds of Canonical Varieties ﻿

(1998)
Artículo
Acceso abierto
We study surfaces and threefolds whose canonical maps are birational (canonical surfaces and threefolds). In the case of canonical surfaces we prove that the known inequlity for its invariants is not sharp if the surface ...
• #### On a conjecture of Fujita ﻿

(2000)
Artículo
Acceso abierto
• #### On the bicanonical map of irregular varieties ﻿

(2010-02)
Report de recerca
Acceso abierto
From the point of view of uniform bounds for the birationality of pluricanonical maps, irregular varieties of general type and maximal Albanese dimension behave similarly to curves. In fact Chen-Hacon showed that, at least ...
• #### On the slope of bielliptic fibrations ﻿

(1997)
Artículo
Acceso abierto
Let $\pi :S\longrightarrow B$ be a bielliptic fibration. We prove $S$ is, up to base change, a rational double cover of an elliptic fibration and that $\pi$ is isotrivial provided it is smooth. Finally, we prove that the ...
• #### On the slope of fibred surfaces ﻿

(1998)
Artículo
Acceso abierto
• #### On the slope of fibred surfaces ﻿

(2000)
Artículo
Acceso abierto
We give an asymptotically sharp lower bound for the slope $\lambda (f)$ of a fibration $f:S\longrightarrow B$, where $S$ is a surface and $B$ is a curve, if there exists an involution on the general fibre $F$ of $f$. ...
• #### On the slope of fibred threefolds ﻿

(1998)
Artículo
Acceso abierto
We study from a geographical point of wiew fibrations of threefolds over smooth curves $f: T \longrightarrow B$ such that the general fibre is of general type. We prove the non-negativity of certain relative invariants under ...
• #### On the topological index of irregular surfaces ﻿

(2005)
Artículo
Acceso abierto
We study the topological index of some irregular surfaces that we call generalized Lagrangian. We show that under certain hypotheses on the base locus of the Lagrangian system the topological index is non-negative. For ...
• #### Positivity properties of relative complete intersections ﻿

(2014-10)
Report de recerca
Acceso abierto
We give conditions for f-positivity of relative complete intersections in projective bundles. We also derive an instability result for the fibres.
• #### Stability and singularities of relative hypersurfaces ﻿

(2014-07-30)
Report de recerca
Acceso abierto
We study relative hypersurfaces, and prove an instability condition for the fibres. This is the starting point for an investigation of the geometry of effective divisors on relative projective bundles.
• #### Surfaces on the Severi line ﻿

(2016-05-01)
Artículo
Acceso abierto
Let S be a minimal complex surface of general type and of maximal Albanese dimension; by the Severi inequality one has K-S(2) >= 4 chi(O-S). We prove that the equality K-S(2) = 4 chi(O-S) holds if and only if q(S) := ...
• #### The representation problem of pairs of symmetric second order tensors in the context of solid mechanics ﻿

(2003)
Report de recerca
Acceso restringido por decisión del autor
• #### The structure and slope of bielliptic fibrations ﻿

(1997)
Artículo
Acceso abierto
• #### Xiao's conjuecture for general fibred surfaces ﻿

(2014-01-10)
Report de recerca
Acceso abierto
We prove that the genus g, the relative irregularity q_f and the Clifford index c_f of a non-isotrivial fibration f satisfy the inequality q_f=g-c_f. This gives in particular a proof of Xiao’s conjecture for fibrations ...