Complements on surfacesThe main result of the paper is a boundedness for n-complements on algebraic surfaces. In addition, applications of this theorem to a classification of log Del Pezzo surfaces and of birational…V. V. Shokurov·Mar 28, 2001SaveLearn
Isolated rational curves on K3-fibered Calabi-Yau threefoldsWe study each of the 16 types of complete intersection Calabi-Yau threefolds in projective n-space times the projective line, for various n, and prove existence of isolated rational curves of…Torsten Ekedahl, Trygve Johnsen, Dag Einar Sommervoll·Jan 24, 2001SaveLearn
Cohomology of complete intersections in toric varietiesThis paper explicitly describes Hodge structures of complete intersections of ample hypersurfaces in compact simplicial toric varieties.Anvar R. Mavlyutov·Dec 20, 2000SaveLearn
The Gross-Kohnen-Zagier theorem in higher dimensionsThe Gross-Kohnen-Zagier theorem describes Heegner points on a modular curve in terms of coefficients of modular forms. We give another proof of this theorem which generalizes to higher dimensions.Richard E. Borcherds·May 12, 2000SaveLearn
Real deformations and complex topology of plane curve singularitiesThis is the paper as published. The topology of a complex plane curve singularity with real branches is deduced from any real deformation having delta crossings. An example of the computation of the…Norbert A'Campo·Apr 3, 2000SaveLearn
Irreducibility of the moduli space of vector bundles on surfaces and Brill-Noether theory on singular curvesWe prove the irreducibility of the moduli space of rank 2 semistable torsion free sheaves (with a generic polarization and any value of c2) on a K3 or a del Pezzo surface. In the case of a K3…Tomas L. Gomez·Mar 23, 2000SaveLearn
Degenerations of (1,3) abelian surfaces and Kummer surfacesWe continue our study of the geometry of Nieto's quintic threefold, looking at degenerate surfaces that correspond to certain loci and showing how they arise from a toroidal compactification of a…K. Hulek, I. Nieto, G. K. Sankaran·Jun 25, 1999SaveLearn
Heisenberg-invariant Kummer surfacesWe study the geometry of Nieto's quintic threefold (Barth & Nieto, J. Alg. Geom. 3, 1994) and the Kummer and abelian surfaces that correspond to special loci.K. Hulek, I. Nieto, G. K. Sankaran·Jun 25, 1999SaveLearn
Zero-pole interpolation for matrix meromorphic functions on a compact Riemann surface, and a matrix Fay trisecant identityThis paper presents a new approach to constructing a meromorphic bundle map between flat vector bundles over a compact Riemann surface having a prescribed Weil divisor (i.e., having prescribed zeros…Joseph A. Ball, Victor Vinnikov·Feb 8, 1999SaveLearn
Involutions on Moduli Spaces and Refinements of the Verlinde FormulaThe moduli space M of semi-stable rank 2 bundles with trivial determinant over a complex curve carries involutions naturally associated to 2-torsion points on the Jacobian of the curve. For every…Jorgen Ellegaard Andersen, Gregor Masbaum·Dec 14, 1998SaveLearn
Ladders on Fano varietiesWe prove the existence of Fano ladders on weak log Fano varieties of coindex less than 4, as an application of adjunction and nonvanishing.Florin Ambro·Dec 1, 1998SaveLearn
Chern Classes of Bundles over Rational SurfacesConsider the blow up π: X X of a rational surface X at a point. Let V be a holomorphic bundle over X whose restriction to the exceptional divisor…Elizabeth Gasparim·Jul 27, 1998SaveLearn
Hypergeometric functions on reductive groupsThe A-hypergeometric system studied by I.M. Gelfand, M.I. Graev, A.V. Zelevinsky and the author, is defined for a set A of characters of an algebraic torus. In this paper we propose a generalization…M. Kapranov·Apr 6, 1998SaveLearn
Stringy Hodge numbers of varieties with Gorenstein canonical singularitiesWe introduce the notion of stringy E-function for an arbitrary normal irreducible algebraic variety X with at worst log-terminal singularities. We prove some basic properties of stringy E-functions…Victor V. Batyrev·Mar 16, 1998SaveLearn
Birational Calabi--Yau n-folds have equal Betti numbersLet X and Y be two smooth projective n-dimensional algebraic varieties X and Y over C with trivial canonical line bundles. We use methods of p-adic analysis on algebraic varieties over local number…Victor V. Batyrev·Mar 16, 1998SaveLearn
On the index of a vector field at an isolated singularityWe consider manifolds with isolated singularities, i.e., topological spaces which are manifolds (say, C∞--) outside discrete subsets (sets of singular points). For (germs of) manifolds with,…Wolfgang Ebeling, Sabir M. Gusein-Zade·Mar 12, 1998SaveLearn
Inequalities for semistable families of arithmetic varietiesIn this paper, we will consider a generalization of Bogomolov's inequality and Cornalba-Harris-Bost's inequality to semistable families of arithmetic varieties under the idea that geometric…Shu Kawaguchi, Atsushi Moriwaki·Mar 3, 1998SaveLearn
Secondary Kodaira-Spencer classes and nonabelian Dolbeault cohomologyIf X is a smooth projective variety moving in a family, we define a secondary Kodaira-Spencer class for nonabelian Dolbeault cohomology Hom(XDol, T) of X with coefficients in the…Carlos Simpson·Jan 6, 1998SaveLearn
Quantum Hyperplane Section Theorem For Homogeneous SpacesWe formulated a mirror-free approach to the mirror conjecture, namely, quantum hyperplane section conjecture, and proved it in the case of nonnegative complete intersections in homogeneous manifolds.…Bumsig Kim·Jan 2, 1998SaveLearn
Comparison of the algebraic and the symplectic Gromov-Witten invariantsWe show that the algebraic and the symplectic GW-inivariants of smooth projective varieties are equivalent.Jun Li, Gang Tian·Jan 1, 1998SaveLearn
Weak approximation, Brauer and R-equivalence in algebraic groups over arithmetical fieldsWe prove some new relations between weak approximation and some rational equivalence relations (Brauer and R-equivalence) in algebraic groups over arithmetical fields. By using weak approximation and…Nguyen Quoc Thang·Dec 31, 1997SaveLearn
On the classification of hyperbolic root systems of the rank three. Part IIHere we prove classification results announced in Part I (alg-geom/9711032). We classify maximal hyperbolic root systems of the rank 3 having restricted arithmetic type and a generalized lattice Weyl…Viacheslav V. Nikulin·Dec 30, 1997SaveLearn
Descent for Shimura VarietiesWe verify that the descent maps provided by Langlands's Conjugacy Conjecture do satisfy the continuity condition necessary for them to be effective. Thus Langlands's conjecture does imply the…J. S. Milne·Dec 30, 1997SaveLearn
Toric Degenerations of Fano Varieties and Constructing Mirror ManifoldsFor an arbitrary smooth n-dimensional Fano variety X we introduce the notion of a small toric degeneration. Using small toric degenerations of Fano n-folds X, we propose a general method for…Victor V. Batyrev·Dec 30, 1997SaveLearn
A morphism of intersection homology induced by an algebraic mapLet f:X-->Y be a map of algebraic varieties. Barthel, Brasselet, Fieseler, Gabber and Kaup have shown that there exists a homomorphism of intersection homology groups f*:IH*(Y)-->IH*(X)…Andrzej Weber·Dec 30, 1997SaveLearn