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Algebraic Geometry papers — page 12

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The deformation theory of local complete intersections
This is an expository paper on the subject of the title. It assumes basic scheme theory, commutative and homological algebra.
Angelo VistoliMar 6, 1997
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The degree of the generators of the canonical ring of surfaces with pg=0
It is shown that the canonical ring of a minimal surface of general type with pg=0, K2≥ 2 is generated by its elements of degree lesser or equal to 5, provided |2K| has no fixed components,…
Margarida Mendes LopesMar 6, 1997
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Examples of smooth non-general type surfaces in P4
The aim of the paper is to provide a series of new examples of smooth surfaces in P4, not of general type, in degrees varying from 12 up to 14, and to describe their geometry. By using mainly…
Sorin PopescuMar 5, 1997
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Applications of Braid Group Techniques to algebraic Surfaces, New examples
Every smooth minimal complex algebraic surface of general type, X, may be mapped into a moduli space, c12(X), c2(X), of minimal surfaces of general type, all of which have the same Chern…
Arthur Robb, Mina TeicherMar 5, 1997
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Geometry of Moduli Spaces of Flat Bundles on Punctured Surfaces
We consider the moduli spaces of flat SL(n, C)-bundles on Riemann surfaces with one puncture when we fix the conjugacy class C of the monodromy transformation around the puncture. We show…
Philip A. FothMar 5, 1997
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Basepoint freeness for big line bundles in positive characteristic, with applications to Mg and to 3-fold MMP
I give a necessary and sufficient condition for a nef and big line bundle in positive characteristic to be semi-ample, and then give two applications: I show that the relative dualizing sheaf of the…
Sean KeelMar 3, 1997
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Complex projective surfaces and infinite groups
The paper contains a general construction which produces new examples of non simply-connected smooth projective surfaces. We analyze the resulting surfaces and their fundamental groups. Many of these…
Fedor Bogomolov, Ludmil KatzarkovMar 3, 1997
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Schubert polynomials, the Bruhat order, and the geometry of flag manifolds
We illuminate the relation between the Bruhat order on the symmetric group and structure constants (Littlewood-Richardson coefficients) for the cohomology of the flag manifold in terms of its basis…
Nantel Bergeron, Frank SottileFeb 28, 1997
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Five Definitions of Critical Point at Infinity
This survey paper discusses five equivalent ways of defining a ``critical point at infinity'' for a complex polynomial of two variables.
Alan H. DurfeeFeb 27, 1997
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On δm constant locus of versal deformations of nondegenerate hypersurface simple K3 singularities
Hypersurface simple K3 singularities defined by nondegenerate quasi-homogeneous polynomials are classified into ninety five classes in term of the weight of the polynomial by T. Yonemura. We consider…
Masako FuruyaFeb 27, 1997
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Braid Group, Algebraic Surfaces and Fundamental Groups of complements of Branch Curves
This paper will appear in the Santa Cruz proceedings. An overview of the braid group techniques in the theory of algebraic surfaces, from Zariski to the latest results, is presented. An outline of…
Mina TeicherFeb 26, 1997
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McKay correspondence
This is a rough write-up of my lecture at Kinosaki and two lectures at RIMS workshops in Dec 1996, on work in progress that has not yet reached any really worthwhile conclusion, but contains lots of…
Miles ReidFeb 25, 1997
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Degenerations of Planar Linear Systems
Fixing n general points pi in the plane, what is the dimension of the space of plane curves of degree d having multiplicity mi at pi for each i? In this article we propose an approach…
C. Ciliberto, R. MirandaFeb 21, 1997
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Semisimple Frobenius (super)manifolds and quantum cohomology of Pr
We introduce and study a superversion of Dubrovin's notion of semisimple Frobenius manifolds. We establish a correspondence between semisimple Frobenius (super)manifolds and special solutions to…
Yu. I. Manin, S. A. MerkulovFeb 21, 1997
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Numerical Criteria for vey Ampleness of Divisors on Projective Bundles over an elliptic curve
In Butler, J.Differential Geom. 39 (1):1--34,1994, the author gives a sufficient condition for a line bundle associated with a divisor D to be normally generated on X=P(E) where E is a vector…
Alberto Alzati, Marina Bertolini, Gian Mario BesanaFeb 20, 1997
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Universal Schubert polynomials
We introduce polynomials that represent general degeneracy loci for maps of vector bundles. These polynomials specialize to the known classical and quantum forms of single and double Schubert…
William FultonFeb 15, 1997
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On extremal contractions from threefolds to surfaces: the case of one non-Gorenstein point and non-singular base surface
In this paper we study a local structure of extrmal contractions f X S from threffolds X with only terminal singularities onto a surface S. If the surface S is non-singular and X…
Yuri G. ProkhorovFeb 15, 1997
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Global Intersection Cohomology of Quasimaps' Spaces
Let C be a smooth projective curve of genus 0. Let be the variety of complete flags in an n-dimensional vector space V. Given an (n-1)-tuple α∈[I] of positive integers one can…
Michael Finkelberg, Alexander KuznetsovFeb 14, 1997
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The Chow Ring of the Moduli Space of Abelian Threefolds
In this paper we determine the structure of the Chow ring of the Delaunay-Voronoi compactification A3 of the moduli space of principally polarized abelian threefolds. This…
Gerard van der GeerFeb 7, 1997
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The Gromov Invariants of Ruan-Tian and Taubes
Taubes has recently defined Gromov invariants for symplectic four-manifolds and related them to the Seiberg-Witten invariants. Independently, Ruan and Tian defined symplectic invariants based on…
Eleny-Nicoleta Ionel, Thomas H. ParkerFeb 6, 1997
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Commutator coverings of Siegel threefolds
We investigate the existence and non-existence of modular forms of low weight with a character with respect to the paramodular group Γt and discuss the resulting geometric consequences. Using an…
V. Gritsenko, K. HulekFeb 6, 1997
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On exponential sums
Let f be a polinomial with coefficients in a finite field F. Let Ψ: F C be a non-trivial additive character. In this paper we give bounds for the exponential sums $Σx∈ Fn…
Ricardo Garcia LopezFeb 6, 1997
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Moishezon Manifolds
Let X be a compact Moishezon manifold which becomes projective after blowing up a smooth subvariety Y ⊂ X. We assume also that there exists a proper map ρ:X X' onto a projective…
Marco AndreattaFeb 4, 1997
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Semistable reduction of abelian varieties over extensions of small degree
We obtain necessary and sufficient conditions for abelian varieties to acquire semistable reduction over fields of low degree. Our criteria are expressed in terms of torsion points of small order…
A. Silverberg, Yu. G. ZarhinFeb 3, 1997
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Principal bundles on elliptic fibrations
A central role in recent investigations of the duality of F-theory and heterotic strings is played by the moduli of principal bundles, with various structure groups G, over an elliptically fibered…
Ron Y. DonagiFeb 3, 1997
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