Skip to content

Algebraic Geometry papers — page 10

alg-geomBrowse archive

Second order theta divisors on Pryms
Van Geemen and van der Geer, Donagi, Beauville and Debarre proposed characterizations of the locus of jacobians which use the linear system of 2Θ-divisors. We give new evidence for these…
E. IzadiApr 23, 1997
Learn
Towards a Halphen theory of linear series on curves
A linear series on a curve C in P3 is "primary" when it does not contain the series cut by planes. We provide a lower bound for the degree of these series, in terms of deg(C), g(C) and of…
Luca Chiantini, Ciro CilibertoApr 19, 1997
Learn
Bertini and his two fundamental theorems
After reviewing Bertini's life story, a fascinating drama, we make a critical examination of the old statements and proofs of Bertini's two fundamental theorems, the theorem on variable…
Steven L. KleimanApr 17, 1997
Learn
An algorithm for computing the integral closure
In this article we give an algorithm for computing the integral closure of a reduced Noetherian ring R, in case this integral closure is finitely generated over R.
Theo de JongApr 16, 1997
Learn
On the irreducibility of the punctual Quotient Scheme of a Surface
We prove that the Quot-scheme of finite quotients of a vector bundle which are of a given length and supported in one point, is irreducible and of the expected dimension.
Geir Ellingsrud, Manfred LehnApr 15, 1997
Learn
Non-Abelian Brill-Noether theory and Fano 3-folds
A Brill-Noether locus is a subscheme of the moduli of bundles E over a curve C defined by requiring E to have a given number of sections, or homomorphisms from another bundle. There are a number of…
Shigeru MukaiApr 15, 1997
Learn
Rozansky-Witten invariants via Atiyah classes
Recently, L.Rozansky and E.Witten (hep-th/9612216) associated to any hyperKaehler manifold X a system of "weights" (numbers, one for each trivalent graph) and used them to construct…
M. KapranovApr 13, 1997
Learn
Intersection Homology of Toric Varieties and a Conjecture of Kalai
We prove that the intersection homology Poincare' polynomial P(X) of an affine toric variety X is bounded below by the product P(Y)P(X/Y), where Y is the closure of any orbit in X and X/Y is a…
Tom C. Braden, Robert D. MacPhersonApr 13, 1997
Learn
Connected components in the intersection of two open opposite Schubert cells in real complete flag manifold
In this paper we reduce the problem of counting the number of connected components in the intersection of two opposite open Schubert cells in the variety of real complete flags to a purely…
B. Shapiro, M. Shapiro, A. VainshteinApr 12, 1997
Learn
Plane curves of minimal degree with prescribed singularities
We prove that there exists a>0 such that for any integer d>2 and any topological types S1,...,Sn of plane curve singularities, satisfying μ(S1)+...+μ(Sn) ≤ ad2, there exists a reduced…
Gert-Martin Greuel, Christoph Lossen, Eugenii ShustinApr 11, 1997
Learn
On fundamental groups of elliptically connected surfaces
A compact complex manifold X is called elliptically connected if any pair of points in X can be connected by a chain of elliptic or rational curves. We prove that the fundamental group of an…
K. Oguiso, M. ZaidenbergApr 11, 1997
Learn
On Degenerations of Fibre Spaces of Curves of Genus >= 2
In this note, we show that for surfaces admitting suitable fibrations, any given degeneration X / Delta is bimeromorphic to a fiber space over Delta and we apply this result to the study of the…
Hursit Onsiper, Sinan SertozApr 11, 1997
Learn
Divisors on elliptic Calabi-Yau 4-folds and the superpotential in F-theory, I
Each smooth elliptic Calabi-Yau 4-fold determines both a three-dimensional physical theory (a compactification of ``M-theory'') and a four-dimensional physical theory (using the…
A. GrassiApr 10, 1997
Learn
A closed model structure for n-categories, internal Hom, n-stacks and generalized Seifert-Van Kampen
We define a closed model category containing the n-nerves defined by Tamsamani, and admitting internal Hom. This allows us to construct the n+1-category nCAT by taking the internal Hom for…
Carlos SimpsonApr 10, 1997
Learn
The global nilpotent variety is Lagrangian
The purpose of this note is to present a short elementary proof of a theorem due to Faltings and Laumon, saying that the global nilpotent cone is a Lagrangian substack in the cotangent bundle of the…
Victor GinzburgApr 10, 1997
Learn
All Abelian Quotient C.I.-Singularities Admit Projective Crepant Resolutions in All Dimensions
For Gorenstein quotient spaces Cd/G, a direct generalization of the classical McKay correspondence in dimensions d≥ 4 would primarily demand the existence of projective, crepant…
Dimitrios I. Dais, Martin Henk, Guenter M. ZieglerApr 10, 1997
Learn
Bend, break and count
We give a 'recursive' formula (in terms of reducible limits) for counting rational curves on a variety moving in any sufficiently large and well-behaved family. Our approach is completely…
Ziv RanApr 9, 1997
Learn
Empty real Enriques surfaces and Enriques-Einstein-Hitchin 4-manifolds
We prove that the moduli space of empty real Enriques surfaces (and, thus, the moduli space of compact orientable 4-dimensional Einstein manifolds whose universal covering is a K3-surface and π1(E)…
A. Degtyarev, V. KharlamovApr 9, 1997
Learn
Birational Models of the Moduli Spaces of Stable Vector Bundles over Curves
We give a method to construct stable vector bundles whose rank divides the degree over curves of genus bigger than one. The method complements the one given by Newstead. Finally, we make some…
Yi Hu, Wei-Ping LiApr 8, 1997
Learn
Tempered currents and the cohomology of the remote fiber of a real polynomial map
Let p:Rn R be a polynomial map. Consider the complex S'Ω*(n) of tempered currents on Rn with the twisted differential dp=d-dp where d is the usual exterior differential and…
Alexander Braverman, Maxim BravermanApr 2, 1997
Learn
On Punctual Quot Schemes for Algebraic Surfaces
The punctual Quot scheme parametrizes all length d quotients of a (locally) trivial rank r sheaf which are supported at a fixed point. The author shows that this scheme is irreducible and…
Vladimir BaranovskyMar 28, 1997
Learn
An Assympotic Vanishing Theorem for Generic Unions of Multiple Points
In this revised form, the proof of the principal lemma has been simplified and the main theorem has been extended to all characteristics for those varieties which are smooth in codimension one. This…
J. Alexander, A. HirschowitzMar 28, 1997
Learn
Very Ampleness and Higher Syzygies for Algebraic Surfaces and Calabi-Yau Threefolds
This work consists of two parts. In the first part we develop new techniques to compute Koszul cohomology groups for several classes of varieties. As applications we prove results on projective…
F. J. Gallego, B. P. PurnaprajnaMar 28, 1997
Learn
The Ideal Generation Problem for Fat Points
This paper is concerned with determining the number of generators in each degree for minimal sets of homogeneous generators for saturated ideals defining fat point subschemes Z=m1p1+ ... +mrpr…
Brian HarbourneMar 27, 1997
Learn
Testing S-duality conjecture and exceptional bundles
In this paper we deal with algebro-geometrical problems connected with testing S-duality conjecture for super-symmetric Yang-Mills quantum field theories in four dimensions. We describe all field…
Boris V. KarpovMar 27, 1997
Learn
← PreviousPage 10Next →