Berührungsbedingungen für p-l-s-Kegelschnitte
Betti numbers for the Hilbert function strata of the punctual Hilbert scheme in two variables.
Bi-extensions associated to divisors on abelian varieties and theta functions
Birational geometry of quadrics
We construct new birational maps between quadrics over a field. The maps apply to several types of quadratic forms, including Pfister neighbors, neighbors of multiples of a Pfister form, and half-neighbors. One application is to determine which quadrics over a field are ruled (that is, birational to the projective line times some variety) in a larger range of dimensions. We describe ruledness completely for quadratic forms of odd dimension at most 17, even dimension at most 10, or dimension 14....
Birational Morphisms to lP2: An Ideal-Theoretic Perspective.
Birational Properties of Moduli spaces of stable locally free rank-2 sheaves on algebraic surfaces.
Bivariant Chern classes for morphisms with nonsingular target varieties
W. Fulton and R. MacPherson posed the problem of unique existence of a bivariant Chern class-a Grothendieck transformation from the bivariant theory F of constructible functions to the bivariant homology theory H. J.-P. Brasselet proved the existence of a bivariant Chern class in the category of embeddable analytic varieties with cellular morphisms. In general however, the problem of uniqueness is still unresolved. In this paper we show that for morphisms having nonsingular target varieties there...
Bounded Picard groups
Boundedness for threefolds in P6 containing a smooth ruled surface as hyperplane section.
Let X ⊂ P6 be a smooth irreducible projective threefold, and d its degree. In this paper we prove that there exists a constant β such that for all X containing a smooth ruled surface as hyperplane section and not contained in a fourfold of degree less than or equal to 15, d ≤ β. Under some more restrictive hypothesis we prove an analogous result for threefolds containing a smooth ruled surface as hyperplane section and contained in a fourfold of degree less than or equal to 15.
Bounds for the number of connected components and the first Betti number mod two of a real algebraic surface
Bounds on the number of non-rational subfields of a function field.
Bounds on the Serre cohomology of projective varieties
Brill–Noether loci for divisors on irregular varieties
We take up the study of the Brill-Noether loci , where is a smooth projective variety of dimension , , and is an integer. By studying the infinitesimal structure of these loci and the Petri map (defined in analogy with the case of curves), we obtain lower bounds for , where is a divisor that moves linearly on a smooth projective variety of maximal Albanese dimension. In this way we sharpen the results of [Xi] and we generalize them to dimension . In the -dimensional case we prove an...
Brill-Noether theory for non-special linear systems
Calabi-Yau manifolds and a conjecture of Kobayashi.
Cancellation Problem of Complete Varieties.
Canonical Classes on Singular Varieties.
Canonical models of surfaces of general type in positive characteristic
Canonical systems of double spaces.
Caractérisation des tissus de C2 dont le rang est maximal et qui sont linéarisables