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Algebraic Geometry papers — page 11

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Rankin-Cohen Type Differential Operators for Siegel Modular Forms
Let Hn be the Siegel upper half space and let F and G be automorphic forms on Hn of weights k and l, respectively. We give explicit examples of differential operators D acting on functions on Hn x…
W. Eholzer, T. IbukiyamaMar 26, 1997
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Projections of Grassmannians of lines and characterization of Veronese varieties
We characterize the double Veronese embedding of Pn as the only variety that, under certain general conditions, can be isomorphically projected from the Grassmannian of lines in P2n+1 to the…
Enrique ArrondoMar 24, 1997
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On the topology of holomorphic bundles
In this work we study the topology of holomorphic rank two bundles over complex surfaces. We consider bundles that are constructed by glueing and show that under certain conditions the topology of…
Elizabeth GasparimMar 24, 1997
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Alexander Invariants of Complex Hyperplane Arrangements
Let A be an arrangement of complex hyperplanes. The fundamental group of the complement of A is determined by a braid monodromy homomorphism from a finitely generated free group to the pure braid…
Daniel C. Cohen, Alexander I. SuciuMar 22, 1997
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Generic Hypersurface Singularities
We give a new differential proof of our result on the maximal rank of generic unions of points of multiplicity two in projective space in degrees greater than five. This simplifies somewhat our proof…
J. Alexander, A. HirschowitzMar 21, 1997
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Interpolation on Jets
We show that for any finite generic union of pairs (xi,Li)i where xi∈ Li is a point of the line Li in projective n-space, the divisors mixi on the Li have maximal rank with…
J. Alexander, A. HirschowitzMar 21, 1997
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Three-block exceptional collections over Del Pezzo surfaces
We study complete exceptional collections of coherent sheaves over Del Pezzo surfaces, which consist of three blocks such that inside each block all Ext groups between the sheaves are zero. We show…
Boris V. Karpov, Dmitri Yu. NoginMar 21, 1997
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Heisenberg invariant quartics and SUC(2) for a curve of genus four
If C is a curve of genus 4 without vanishing theta-nulls then there exists a unique (irreducible) Heisenberg-invariant quartic QC in |2Θ| = P15 such that Sing QC contains the image of SUC(2),…
William Oxbury, Christian PaulyMar 21, 1997
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On the quotient of the braid group by commutators of transversal half-twists and its group actions
The group described in this paper appeared while studying fundamental groups of complements of branch curves. It turned out that a certain quotient of the braid group acts on those fundamental groups…
Mina TeicherMar 20, 1997
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On Betti numbers and Chern classes of varieties with trivial odd cohomology groups
It was noticed in a very recent preprint of T. Eguchi, K. Hori, and Ch.-Sh. Xiong (hep-th/9703086) that a curious identity between Betti numbers and Chern classes holds for many examples of Fano…
Lev A. BorisovMar 19, 1997
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A note on P-resolutions of cyclic quotient singularities
P-resolutions of a cyclic quotient singularity are known to be in one-to-one correspondence with the components of the base space of its semi-universal deformation. Stevens and Christophersen have…
Ludwig BalkeMar 19, 1997
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Geometric Realization of Whittaker Functions and the Langlands Conjecture
We prove the equivalence of two conjectural constructions of unramified cuspidal automorphic functions on the adelic group GLn(A) associated to an irreducible l-adic local system of rank n on an…
E. Frenkel, D. Gaitsgory, D. Kazhdan et al.Mar 18, 1997
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Determinant bundles for abelian schemes
To a symmetric, relatively ample line bundle on an abelian scheme one can associate a linear combination of the determinant bundle and the relative canonical bundle, which is a torsion element in the…
Alexander PolishchukMar 18, 1997
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Standard Monomial Theory for Bott-Samelson Varieties of GL(n)
We construct an explicit basis for the coordinate ring of the Bott-Samelson variety Zi associated to G = GL(n) and an arbitrary sequence of simple reflections i. Our basis is parametrized by certain…
V. Lakshmibai, Peter MagyarMar 15, 1997
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A New look at the vortex equations and dimensional reduction
In order to use the technique of dimensional reduction, it is usually necessary for there to be a symmetry coming from a group action. In this paper we consider a situation in which there is no such…
Steven Bradlow, James Glazebrook, Franz KamberMar 14, 1997
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Mixed Segre Numbers and Integral Closure of Ideals
We introduce mixed Segre numbers of ideals which generalize the notion of mixed multiplicities of ideals of finite colength and show how many results on mixed multiplicities can be extended to…
Robert GasslerMar 13, 1997
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Chern Classes of Fibered Products of Surfaces
In this paper we introduce a formula to compute Chern classes of fibered products of algebraic surfaces. For f, a generic projection to CP2, of an algebraic surface X, we define Xk (for k smaller…
Mina TeicherMar 12, 1997
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Hypercomplex Varieties
We give a number of equivalent definitions of hypercomplex varieties and construct a twistor space for a hypercomplex variety. We prove that our definition of a hypercomplex variety (used, e. g., in…
Misha VerbitskyMar 12, 1997
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Associativity relations in quantum cohomology
We describe interdependencies among the quantum cohomology associativity relations. We strengthen the first reconstruction theorem of Kontsevich and Manin by identifying a subcollection of the…
Andrew KreschMar 11, 1997
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Contact Cohomology of the Projective Plane
We construct an associative ring which is a deformation of the quantum cohomology ring of the projective plane. Just as the quantum cohomology encodes the incidence characteristic numbers of rational…
Lars Ernström, Gary KennedyMar 10, 1997
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Derivation algebras of toric varieties
Normal affine algebraic varieties in characteristic 0 are uniquely determined (up to isomorphism) by the Lie algebra of derivations of their coordinate ring. This is not true without the hypothesis…
Antonio Campillo, Janusz Grabowski, Gerd MüllerMar 10, 1997
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Moduli of flat bundles on open Kaehler manifolds
We consider the moduli space MN of flat unitary connections on an open Kaehler manifold U (complement of a divisor with normal crossings) with restrictions on their monodromy transformations. Using…
Jean-Luc Brylinski, Philip FothMar 9, 1997
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Moduli of regular holonomic D-modules with normal crossing singularities
This paper solves the global moduli problem for regular holonomic D-modules with normal crossing singularities on a nonsingular complex projective variety. This is done by introducing a level…
Nitin NitsureMar 9, 1997
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Perverse Sheaves on Loop Grassmannians and Langlands Duality
We outline a proof of a geometric version of the Satake isomorphism. Given a connected, complex algebraic reductive group G we show that the tensor category of representations of the dual group…
Ivan Mirković, Kari VilonenMar 9, 1997
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A Remark on the Geometry of Elliptic Scrolls and Bielliptic Surfaces
The union of two quintic elliptic scrolls in P4 intersecting transversally along an elliptic normal quintic curve is a singular surface Z which behaves numerically like a bielliptic surface. In the…
C. Ciliberto, K. HulekMar 7, 1997
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