Pluriadjoint Bundles of Polarized Surfaces.
Geometric genera for ample vector bundles with regular sections.
Let X be a smooth complex projective variety of dimension n ≥ 3. A notion of geometric genus p(X,E) for ample vector bundles E of rank r < n on X admitting some regular sections is introduced. The following inequality holds: p(X,E) ≥ h(X). The question of characterizing equality is discussed and the answer is given for E decomposable of corank 2. Some conjectures suggested by the result are formulated.
On the existence of scrolls in
Si dimostra il seguente risultato. Sia una superficie proiettivamente rigata, non iperpiana, di ; allora è la rigata cubica oppure è una rigata quintica ellittica. Si descrive inoltre una nuova generazione proiettiva delle rigate quintiche ellittiche di .
Su un teorema di Chisini
Two general multiple planes having the same branch curve cannot be too "different". As it is well known, a central result in the theory of multiple planes, first proved by Chisini in [3], asserts that two such multiple planes, with some additional hypothesis, are birational. In this paper we prove, with a different additional hypothesis, that two general multiple planes having the same branch curve are isomorphic. Let S be a complex projective non-singular algebraic surface, R a net on S, the...
On the 2 and the 3-connectedness of ample divisors on a surface.
Erratum to "On the 2 and the 3-Connectedness of ample divisors on a surface".
About the adjunction process for polarized algebraic surfaces.
Adjoint bundles of ample and spanned vector bundles on algebraic surfaces.
On complex projective surfaces with trigonal hyperplane sections.
Characterizing Projective Bundles by Means of Ample Divisors.
Erratum to "On complex projective surfaces with trigonal hyperplane sections".
Geometrically ruled surfaces as zero loci of ample vector bundles.
Ample and spanned vector bundles of sectional genera three.
Adjunction properties of polarized surfaces via Reider's method.
Projective 7-folds with positive defect
Elliptic sufaces with a nef line bundle of genus two.
Complex projective elliptic surfaces endowed with a numerically effective line bundle of arithmetic genus two are studied and partially classified. A key role is played by elliptic quasi-bundles, where some ideas developed by Serrano in order to study ample line bundles apply to this more general situation.
A footnote to a paper by Noma
Let be a globally generated ample vector bundle of rank on a complex projective smooth surface . By extending a recent result by A. Noma, we classify pairs as above satisfying .
On the adjoint system to a very ample divisor on a surface and connected inequalities
Si caratterizzano alcune classi di superfici in relazione all’indice di autointersezione dell'aggiunto ad un divisore molto ampio.
Some topological conditions for projective algebraic manifolds with degenerate dual varieties: connections with -bundles
Si illustrano alcune relazioni tra le varietà proiettive complesse con duale degenere, le varietà la cui topologia si riflette in quella della sezione iperpiana in misura maggiore dell'ordinario e le varietà fibrate in spazi lineari su di una curva.
On the adjoint system to a very ample divisor on a surface and connected inequalities
Siano: una superficie algebrica proiettiva complessa non singolare, un divisore canonico ed un divisore molto ampio su . Questo lavoro ha per oggetto lo studio dell'indice di autointersezione . Si dimostra, innanzitutto, la disuguaglianza , nell'ipotesi che la superficie ottenuta immergendo mediante il sistema lineare completo non sia uno scroll. Questa disuguaglianza è connessa con alcuni risultati di Sommese e Van de Ven sulla generazione del fascio . La dimostrazione della (I)...
Page 1 Next