A Remark on a Theorem by Fornaess and Narasimhan About the Levi Problem.
On ample and spanned vector bundles with zero ...-genera.
On the dual variety in characteristic 2
Real Moduli of Complex Objects: Surfaces and Bundles.
On Ample and spanned Rank-3 Bundles with Low Chern numbers.
Complete families of rank 2 stable vector bundles on algebraic surfaces.
On the components of moduli of simple sheaves on a surface.
On rank two vector bundles on an algebraic surface.
On the weak non-defectivity of veronese embeddings of projective spaces
Fix integers n, x, k such that n≥3, k>0, x≥4, (n, x)≠(3, 4) and k(n+1)<(nn+x). Here we prove that the order x Veronese embedding ofP n is not weakly (k−1)-defective, i.e. for a general S⊃P n such that #(S) = k+1 the projective space | I 2S (x)| of all degree t hypersurfaces ofP n singular at each point of S has dimension (n/n+x )−1− k(n+1) (proved by Alexander and Hirschowitz) and a general F∈| I 2S (x)| has an ordinary double point at each P∈ S and Sing (F)=S.
Components with the expected codimension in the moduli scheme of stable spin curves
Here we study the Brill-Noether theory of “extremal” Cornalba’s theta-characteristics on stable curves C of genus g, where “extremal” means that they are line bundles on a quasi-stable model of C with #(Sing(C)) exceptional components
On the real X -ranks of points of P n (R) with respect to a real variety X ⊂ P n
Let X ⊂ Pn be an integral and non-degenerate m-dimensional variety defined over R. For any P ∈ Pn(R) the real X-rank r x,R(P) is the minimal cardinality of S ⊂ X(R) such that P ∈ . Here we extend to the real case an upper bound for the X-rank due to Landsberg and Teitler.
Postulation and gonality for projective curves
Fibrati principali su spazi complessi -completi
Normal bundle to curves in quadrics
On projective degenerations of Veronese spaces
Here we give several examples of projective degenerations of subvarieties of . The more important case considered here is the d-ple Veronese embedding of ; we will show how to degenerate it to the union of n-dimensional linear subspaces of 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 postulation...
Gonality for stable curves and their maps with a smooth curve as their target
Here we study the deformation theory of some maps f: X → ℙr , r = 1, 2, where X is a nodal curve and f|T is not constant for every irreducible component T of X. For r = 1 we show that the “stratification by gonality” for any subset of [...] with fixed topological type behaves like the stratification by gonality of M g.
A splitting theorem for the Kupka component of a foliation of . Addendum to an addendum to a paper by Calvo-Andrade and Soares
Here we show that a Kupka component of a codimension 1 singular foliation of is a complete intersection. The result implies the existence of a meromorphic first integral of . The result was previously known if was assumed to be not a square.
A splitting theorem for the Kupka component of a foliation of . Addendum to a paper by O. Calvo-Andrade and N. Soares
Here we show that a Kupka component of a codimension 1 singular foliation of with not a square is a complete intersection. The result implies the existence of a meromorphic first integral of .
An example of a Banach space V such that all the degree ≥ 2 hypersurfaces of P(V) are singular.
Here we give an example of a Banach space V such that all the degree ≥ 2 hypersurfaces of P(V) are singular.
On the homogeneous ideal of collinear punctual subschemes of P.
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