The L2 dbar method, weak Lefschetz theorems, and the topology of Kahler manifoldsA new approach to Nori's weak Lefschetz theorem is described. The new approach, which involves the dbar-method, avoids moving arguments and gives much stronger results. In particular, it is…T. Napier, M. Ramachandran·Dec 29, 1997SaveLearn
Reconstruction of a variety from the derived category and groups of autoequivalencesWe consider smooth algebraic varieties with ample either canonical or anticanonical sheaf. We prove that such a variety is uniquely determined by its derived category of coherent sheaves. We also…A. Bondal, D. Orlov·Dec 24, 1997SaveLearn
Deformations of canonical singularitiesWe prove that small deformations of canonical singularities are canonical.Yujiro Kawamata·Dec 22, 1997SaveLearn
Symmetric matrices and quantum codesThis paper has been withdrawn since a Gilbert-Varshamov bound for general quantum codes has already appeared in Ekert and Macchiavello, Prys. Rev. Lett. 77, p. 2585, and a Gilbert-Varshamov bound for…Vladimir D. Tonchev·Dec 22, 1997SaveLearn
The arithmetic-geometric mean and isogenies for curves of higher genusComputation of Gauss's arithmetic-geometric mean involves iteration of a simple step, whose algebro-geometric interpretation is the construction of an elliptic curve isogenous to a given one,…Ron Donagi, Ron Livne·Dec 21, 1997SaveLearn
Symplectic cutting of Kaehler manifoldsWe obtain estimates on the character of the cohomology of an S1-equivariant holomorphic vector bundle over a Kaehler manifold M in terms of the cohomology of the Lerman symplectic cuts and the…Maxim Braverman·Dec 19, 1997SaveLearn
A canonical lift of Chern-Mather classesThere are several ways to generalize characteristic classes for singular algebraic varieties. The simplest ones to describe are Chern-Mather classes obtained by Nash blow up. They serve as an…Jean-Paul Brasselet, Andrzej Weber·Dec 19, 1997SaveLearn
Poisson structures and birational morphisms associated with bundles on elliptic curvesIn this paper we define a Poisson structure on some moduli spaces related to principal G-bundles on elliptic curves, the simplest example being the moduli space of stable pairs: a vector bundle and…Alexander Polishchuk·Dec 19, 1997SaveLearn
Analogue of Weil representation for abelian schemesIn this paper we construct a projective action of certain arithmetic group on the derived category of coherent sheaves on an abelian scheme A, which is analogous to Weil representation of the…Alexander Polishchuk·Dec 19, 1997SaveLearn
On the cone of curves of an abelian varietyLet X be a smooth projective variety over the complex numbers. One knows by the Cone Theorem that the closed cone of curves of X is rational polyhedral whenever c1(X) is ample. For varieties…Thomas Bauer·Dec 17, 1997SaveLearn
Tamagawa numbers of polarized algebraic varietiesLet L = (L, \| · \|v) be an ample metrized invertible sheaf on a smooth quasi-projective algebraic variety V defined over a number field. Denote by N(V, L,B) the number of…Victor V. Batyrev, Yu. Tschinkel·Dec 17, 1997SaveLearn
Derived categories of coherent sheaves on abelian varieties and equivalences between themWe study derived categories of coherent sheaves on abelian varieties. We give a criterion for the equivalence of the derived categories on two abelian varieties. We describe the autoequivalence group…Dmitri Orlov·Dec 16, 1997SaveLearn
The Character of the Infinite Wedge RepresentationWe study the character of the infinite wedge projective representation of the algebra of differential operators on the circle. We prove quasi-modularity of this character and also compute certain…Spencer Bloch, Andrei Okounkov·Dec 16, 1997SaveLearn
Invariance of PlurigeneraThe following conjecture on the deformation invariance of plurigenera is proved. For a smooth projective holomorphic family of compact complex manifolds over the open unit 1-disk such that all the…Yum-Tong Siu·Dec 15, 1997SaveLearn
The universal regular quotient of the Chow group of 0-cycles on a singular projective varietyWe show the existence of a regular universal quotient as a smooth commutative algebraic group of the Chow group of 0-cycles on a projective reduced variety, and give over the field of complex numbers…Hélène Esnault, V. Srinivas, Eckart Viehweg·Dec 15, 1997SaveLearn
Subadjunction of log canonical divisors IIWe extend a subadjunction formula of log canonical divisors as in [K3] to the case when the codimension of the minimal center is arbitrary by using the positivity of the Hodge bundles.Yujiro Kawamata·Dec 15, 1997SaveLearn
Eigenvalues of products of unitary matrices and quantum Schubert calculusWe describe the inequalities on the possible eigenvalues of products of unitary matrices in terms of quantum Schubert calculus. Related problems are the existence of flat connections on the punctured…Sharad Agnihotri, Chris Woodward·Dec 14, 1997SaveLearn
Hyperholomorphic sheaves and new examples of hyperkaehler manifoldsGiven a compact hyperkaehler manifold M and a holomorphic bundle B over M, we consider a Hermitian connection ∇ on B which is compatible with all complex structures on M induced by the…Misha Verbitsky·Dec 11, 1997SaveLearn
Mirror Principle IWe propose and study the following Mirror Principle: certain sequences of multiplicative equivariant characteristic classes on Kontsevich's stable map moduli spaces can be computed in terms of…B. Lian, K. Liu, S. T. Yau·Dec 11, 1997SaveLearn
Structures du cube et fibres d'intersectionWe define the notion of a hypercube structure on a functor between two strictly commutative Picard categories which generalizes the notion of a cube structure on a Gm-torsor over an abelian…Francois Ducrot·Dec 10, 1997SaveLearn
Algorithmic Computation of Local Cohomology Modules and the Cohomological Dimension of Algebraic VarietiesIn this paper we present algorithms that compute certain local cohomology modules associated to a ring of polynomials containing the rational numbers. In particular we are able to compute the local…Uli Walther·Dec 9, 1997SaveLearn
Toric varieties and minimal complexesWe translate the equivariant decomposition theorem (in the case of a proper morphism of toric varieties) in to the language of combinatorially defined ``shifted minimal complexes''.Paul Bressler, Valery Lunts·Dec 5, 1997SaveLearn
Homological infiniteness of Torelli groupsWe prove that rational homology of the Torelli group of genus g is infinite dimensional, provided g>6. This means that rational homology of the Torelli space of genus g>6 is infinite dimensional. The…Toshiyuki Akita·Dec 3, 1997SaveLearn
Real Algebraic Threefolds II: Minimal Model ProgramThis is the second of a series of papers studying real algebraic threefolds using the minimal model program. The main result is the following. Let X be a smooth projective real algebraic 3-fold.…János Kollár·Dec 2, 1997SaveLearn
Real Algebraic Threefolds I: Terminal SingularitiesThis is the first of a series of papers studying real algebraic threefolds using the minimal model program. The main results are outlined in Part II. The present part I. contains the necessary…János Kollár·Dec 2, 1997SaveLearn