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Algebraic Geometry papers — page 30

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Curves that change genus can have arbitrarily many rational points
A singular curve over a non-perfect field K may not have a smooth model over K. Those are said to "change genus". If K is a global field of positive characteristic and C/K a curve that change…
Jose' Felipe VolochJun 6, 1995
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Hermitian-Einstein Inequalities and Harder-Narasimhan Filtration
Unstable holomorphic bundles can be described algebraically by Harder-Narasimhan filtrations. In this note we show how such filtrations correspond to the existence of special metrics defined by…
Steven B. BradlowJun 5, 1995
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On localization and Riemann-Roch numbers for symplectic quotients
Suppose (M,ω) is a compact symplectic manifold acted on by a compact Lie group K in a Hamiltonian fashion, with moment map μ: M (K)* and Marsden-Weinstein reduction $Mred =…
Lisa C. Jeffrey, Frances C. KirwanJun 4, 1995
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On Alternative Supermatrix Reduction
We consider a nonstandard odd reduction of supermatrices (as compared with the standard even one) which arises in connection with possible extension of manifold structure group reductions. The study…
Steven DuplijJun 2, 1995
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A note on the genus of certain curves over finite fields
We prove the following result which was conjectured by Stichtenoth and Xing: let g be the genus of a projective, irreducible non-singular curve over the finite field Fq2 and whose number…
Rainer Furhmann, Fernando TorresJun 2, 1995
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Open problems on open algebraic varieties
This report records a large number of open problems in Affine Algebraic Geometry that were proposed by participants in a Conference on Open Algebraic Varieties at the Centre de Recherches en…
R. V. Gurjar, Shulim Kaliman, N. Mohan Kumar et al.Jun 2, 1995
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On exotic algebraic structures on affine spaces
By an exotic algebraic structure on the affine space Cn we mean a smooth affine algebraic variety which is diffeomorphic to R2n but not isomorphic to Cn. This is a survey…
Mikhail ZaidenbergJun 2, 1995
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The index of grad f(x,y)
Let f(x,y) be a real polynomial of degree d with isolated critical points, and let i be the index of grad f around a large circle containing the critical points. An elementary argument shows…
Alan H. DurfeeJun 1, 1995
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Composite Differentiable Functions
We introduce a new point of view towards Glaeser's theorem on composite C∞ functions [Ann. of Math. 1963], with respect to which we can formulate a ``Ck composite function…
Edward Bierstone, Pierre D. Milman, Wieslaw PawluckiJun 1, 1995
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Uniformity of stably integral points on elliptic curves
A common practice in arithmetic geometry is that of generalizing rational points on projective varieties to integral points on quasi-projective varieties. Following this practice, we demonstrate an…
Dan AbramovichJun 1, 1995
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Hodge groups of abelian varieties with purely multiplicative reduction
The main result of the paper is that if A is an abelian variety over a subfield F of C, and A has purely multiplicative reduction at a discrete valuation of F, then the Hodge group…
A. Silverberg, Yu. G. ZarhinMay 31, 1995
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Del Pezzo surfaces over Dedekind schemes
Let S be a Dedekind scheme with fraction field K. We study the following problem: given a Del Pezzo surface X, defined over K, construct a distinguished integral model of X, defined over all of S. We…
Alessio CortiMay 31, 1995
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Semistable 3-fold flips
We piece together ingredients, which are well known and documented in the literature, into a new proof of the existence of semistable 3-fold flips
Alessio CortiMay 31, 1995
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Symmetric subgroups of rational groups of hermitian type
A rational group of hermitian type is an algebraic group over the rational numbers whose symmetric space is a hermitian symmetric space. We assume such a group G to be given, which we assume is…
Bruce HuntMay 29, 1995
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The fiber of the Griffiths map for the non-hyperelliptic Fano threefolds of genus 6
Among smooth non-rational Fano 3-folds, the non-hyperelliptic Fano 3-fold X(10) of genus 6 has the unique property to admit a non-trivial orbit of birationally isomorphic 3-folds, inside its moduli…
Atanas IlievMay 29, 1995
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Minimal sections of conic bundles
Let the threefold X be a general smooth conic bundle over the projective plane P(2), and let (J(X), Theta) be the intermediate jacobian of X. In this paper we prove the existence of two natural…
Atanas IlievMay 29, 1995
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How to tell you're hearing a Calabi-Yau: Universal variations of Hodge structure and local Schottky relations for Calabi-Yau manifolds
A revised version with a number of corrections and refinements.
Ziv RanMay 28, 1995
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Quaternionic Monopoles
We present the simplest non-abelian version of Seiberg-Witten theory: Quaternionic monopoles. These monopoles are associated with Spinh(4)-structures on 4-manifolds and form finite-dimensional…
Ch. Okonek, A. TelemanMay 27, 1995
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Flips from semi-stable 4-folds whose degenerate fibers are unions of Cartier divisors which are terminal factorial 3-folds
We shall investigate flipping contractions from a semi-stable 4-fold X whose degenerate fiber is a union of Cartier divisors which are terminal factorial 3-folds. Especially we shall prove that X…
Yasuyuki KachiMay 26, 1995
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Determinant of Period Integral
Period integrals arise from the comparison between Betti cohomologies and de Rham cohomologies. In this paper, we give a formula for the determinant of period integrals in terms of the canonical…
Takeshi Saito, Tomohide TerasomaMay 26, 1995
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On the local geometry of moduli spaces of vector bundles
We give a canonical description of the formal moduli space of a vector bundle on a variety; as an application, we prove the closedness of certain differential forms on moduli corresponding to the…
Ziv RanMay 25, 1995
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Determinant Bundles, Quillen Metrics, and Mumford Isomorphisms Over the Universal Commensurability Teichmüller Space
There exists on each Teichmüller space Tg (comprising compact Riemann surfaces of genus g), a natural sequence of determinant (of cohomology) line bundles, DETn, related to each other via…
Indranil Biswas, Subhashis Nag, Dennis SullivanMay 24, 1995
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Topological invariants of a fan associated to a toric variety
Associated to a toric variety X of dimension r over a field k is a fan Δ on Rr. The fan Δ is a finite set of cones which are in one-to-one correspondence with the orbits of the…
Timothy J. FordMay 24, 1995
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A Note On Elliptic Plane Curves With Fixed j-Invariant
Let Nd be the number of degree d, nodal, rational plane curves through 3d-1 points in the complex projective plane. The number of degree d>=3, nodal, elliptic plane curves with a fixed (general)…
R. PandharipandeMay 24, 1995
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A Geometric Invariant Theory Compactification of Mg,n Via the Fulton-MacPherson Configuration Space
A compactification over Mg of Mg,n is obtained by considering the relative Fulton-MacPherson configuration space of the universal curve. The resulting compactification differs from…
R. PandharipandeMay 23, 1995
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