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Algebraic Geometry papers — page 15

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On the density of ratios of Chern numbers of embedded threefolds
We show that the limit points of (x,y) for all 3-folds in P5 with the Chern ratios x=c13/c1c2, y=c3/c1c2 must lie on the line segment x+y=2, 1 x 2. (Note that the determinantal…
Mei-Chu ChangNov 22, 1996
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On symmetric degeneracy loci, spaces of symmetric matrices of constant rank and dual varieties
Let X be a nonsingular simply connected projective variety of dimension m, E a rank n vector bundle on X, and L a line bundle on X. Suppose that S2(E*) L is an ample vector bundle and…
Bo Ilic, J. M. LandsbergNov 20, 1996
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Existence of good divisors on Mukai manifolds
A normal projective variety X is called Fano if a multiple of the anticanonical Weil divisor, -KX, is an ample Cartier divisor, the index of a Fano variety is the number i(X):=supt: -KX= tH, for…
Massimiliano MellaNov 20, 1996
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Virtual neighborhoods and pseudo-holomorphic curves
We use virtual neighborhood technique to establish GW-invariants, Quantum cohomology, equivariant GW-invariants, equivariant quantum cohomology and Floer cohomology for general symplectic manifold.…
Yongbin RuanNov 19, 1996
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Separation of Semialgebraic Sets
In this paper we study the problem of deciding whether two disjoint semialgebraic sets of an algebraic variety over R are separable by a polynomial. For that we isolate a dense subfamily of Spaces of…
F. Acquistapace, C. Andradas, F. BrogliaNov 19, 1996
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Bornes effectives pour la torsion des courbes elliptiques sur les corps de nombres
In this paper we give a detailed proof of a result we announced a year ago. This result is an effective version of the theorem of Mazur-Kamienny-Merel concerning uniform bounds for rational torsion…
Pierre ParentNov 19, 1996
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Liouville and Carathéodory coverings in Riemannian and complex geometry
A Riemannian manifold resp. a complex space X is called Liouville if it carries no nonconstant bounded harmonic resp. holomorphic functions. It is called Carathéodory, or Carathéodory hyperbolic,…
Vladimir Lin, Mikhail ZaidenbergNov 18, 1996
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Bott-Samelson Varieties and Configuration Spaces
We give a new construction of the Bott-Samelson variety Z as the closure of a B-orbit in a product of flag varieties (G/B)l. This also gives an embedding of the projective coordinate ring of…
Peter M. MagyarNov 16, 1996
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Algebraic Differential Characters
We give a construction of algebraic differential characters, receiving classes of algebraic bundles with connection, lifitng the Chern-Simons invariants defined with S. Bloch, the classes in the Chow…
Hélène EsnaultNov 15, 1996
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A view on contractions of higher dimensional varieties
In this paper we discuss some recent results about extremal contractions of complex algebraic varieties. These are proper surjective maps, ϕ: X Z, of normal varieties with connected…
Marco Andreatta, Jaroslaw A. WiśniewskiNov 14, 1996
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Giambelli-type formula for subbundles of the tangent bundle
Let us consider a generic n-dimensional subbundle V of the tangent bundle TM on some given manifold M. Given V one can define different degeneracy loci Sr(CV), r=(r1<= r2<= r3<=...<=rk) on M…
M. E. Kazarian, B. ShapiroNov 13, 1996
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Desingularization of singular hyperkaehler varieties I
Let M be a singular hyperkaehler variety, obtained as a moduli space of stable holomorphic bundles on a compact hyperkaehler manifold (alg-geom/9307008). Consider M as a complex variety in one of…
Misha VerbitskyNov 12, 1996
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Andre-Quillen cohomology of monoid algebras
We compute the Andre-Quillen cohomology of an affine toric variety. The best results are obtained either in the general case for the first three cohomology groups, or in the case of isolated…
Klaus Altmann, Arne B. SletsjoeNov 12, 1996
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On the semi-simplicity of the Up-operator on modular forms
Let p be a prime number and N an integer prime to p. We show that the operator Up on the space of cuspidal modular forms of level pN and weight two is semi-simple. It follows from this…
Robert F. Coleman, Bas EdixhovenNov 12, 1996
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The quantum cohomology of blow-ups of P2 and enumerative geometry
We compute the Gromov-Witten invariants of the projective plane blown up in r general points. These are determined by associativity from r+1 intial values. Applications are given to the enumeration…
Lothar Göttsche, Rahul PandharipandeNov 11, 1996
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Dynkin Graphs, Gabriélov Graphs and Triangle Singularities
Fourteen kinds of triangle singularities with modality one in Arnold's classification list are discussed. We consider which kinds of combinations of rational double points can appear on small…
Tohsuke UrabeNov 10, 1996
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On the Complexity of Smooth Projective Toric Varieties
In this paper we answer a question posed by V.V. Batyrev. The question asked if there exists a complete regular fan with more than quadratically many primitive collections. We construct a smooth…
Serkan HostenNov 8, 1996
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Birational automorphisms of algebraic varieties with a pencil of cubic surfaces
It is proved that on a smooth algebraic variety, fibered into cubic surfaces over the projective line and sufficiently ``twisted'' over the base, there is only one pencil of rational surfaces…
Aleksandr V. PukhlikovNov 8, 1996
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Projective Moduli for Hitchin Pairs
We give an algebraic geometric compactification of certain moduli spaces of semistable E-pairs in the sense of Yokogawa. In particular, we obtain a compactification of the moduli spaces of semistable…
Alexander SchmittNov 8, 1996
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Bott-Chern Forms and Arithmetic Intersections
Let : 0 --> S --> E --> Q --> 0 be a short exact sequence of hermitian vector bundles with metrics on S and Q induced from that on E. We compute the Bott-Chern form of corresponding to any…
Harry TamvakisNov 6, 1996
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Higher Bott Chern forms and Beilinson's regulator
Let X be a smooth complex algebraic variety. In this paper, we associate, to each exact n-cube of hermitian vector bundles over X, a differential form, called higher Bott Chern form, which…
Jose I. Burgos, Steve WangNov 6, 1996
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Arithmetic Intersection Theory on Flag Varieties
Let F be the complete flag variety over Spec(Z) with the tautological filtration 0 ⊂ E1 ⊂ E2 ⊂ ... ⊂ En=E of the trivial bundle E over F. The trivial hermitian metric on…
Harry TamvakisNov 6, 1996
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The Second Cohomology with Symplectic Coefficients of the Moduli Space of Smooth Projective Curves
Each finite dimensional irreducible rational representation V of the symplectic group Sp2g determines a generically defined local system over the moduli space Mg of genus g smooth projective…
Alexandre KabanovNov 4, 1996
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Resolving mixed Hodge modules on configuration spaces
Given a mixed Hodge module E on a scheme X over the complex numbers, and a quasi-projective morphism f:X->S, we construct in this paper a natural resolution of the nth exterior tensor power of E…
Ezra GetzlerNov 3, 1996
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Segre Numbers and Hypersurface Singularities
We define the Segre numbers of an ideal as a generalization of the multiplicity of an ideal of finite colength. We prove generalizations of various theorems involving the multiplicity of an ideal…
Terence Gaffney, Robert GasslerNov 1, 1996
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