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Algebraic Geometry papers — page 45

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A Kaehler Structure on the Space of String World-Sheets
Let (M,g) be an oriented Lorentzian 4-manifold, and consider the space S of oriented, unparameterized time-like 2-surfaces in M (string world-sheets) with fixed boundary conditions. Then the…
Claude LeBrunMay 26, 1993
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On the fundamental group of an abelian cover
We study the behaviour of the topological fundamental group under totally ramified abelian covers (a special case of abelian Galois covers) of complex projective varieties of dimension at least 2.
Rita Pardini, Francesca TovenaMay 20, 1993
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Finding Sparse Systems of Parameters
For several computational procedures such as finding radicals and Noether normalizations, it is important to choose as sparse as possible a system of parameters in a polynomial ideal or modulo a…
David Eisenbud, Bernd SturmfelsMay 20, 1993
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On the approximate roots of polynomials
We give a simplified approach to the Abhyankar--Moh theory of approximate roots. Our considerations are based on properties of the intersection multiplicity of local curves.
Janusz Gwoździewicz, Arkadiusz PłoskiMay 19, 1993
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Injectivity on one line
Let k be an algebraically closed field of characteristic zero. Let H:k2 k2 be a polynomial mapping such that the Jacobian Jac\,H is a non-zero constant. In this note we prove, that…
Janusz GwoździewiczMay 19, 1993
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An inequality for polynomial mappings
We give an estimate of the growth of a polynonial mapping of Cn.
Arkadiusz PłoskiMay 19, 1993
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The Noether exponent and Jacobi formula
For any polynomial mapping F=(F1,… ,Fn) of Cn with a finite number of zeros we define the Noether exponent ν(F). We prove the Jacobi formula for all polynomials of degree strictly…
Arkadiusz PłoskiMay 19, 1993
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Inequality of Bogomolov-Gieseker's type on arithmetic surfaces
Let K be an algebraic number field, OK the ring of integers of K, and f : X --> Spec(OK) an arithmetic surface. Let (E, h) be a rank r Hermitian vector bundle on X such that E is semistable on…
Atsushi MoriwakiMay 12, 1993
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Kodaira energies of polarized log varieties
Let L be an ample line bundle on a log variety (V, D) having only log terminal singularities.The Kodaira energy of such a triple (V, D, L) is defined as follows: κε=-Inft∈ Q | K(V,D)+tL is big.…
T. FujitaMay 7, 1993
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Log contractions and equidimensional models of elliptic threefolds
This work was initially motivated by Miranda's work on elliptic Weierstrass threefolds. Miranda [Mi] describes a smooth equidimensional (flat) model for any elliptic Weierstrass threefold; such…
A. GrassiMay 5, 1993
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A General Noether-Lefschetz Theorem and applications
In this paper we generalize the classical Noether-Lefschetz Theorem to arbitrary smooth projective threefolds. Let X be a smooth projective threefold over complex numbers, L a very ample line…
Kirti JoshiMay 3, 1993
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A Finiteness Theorem for Elliptic Calabi-Yau Threefolds
We prove that up to birational equivalence, there exists only a finite number of families of Calabi-Yau threefolds (i.e. a threefold with trivial canonical class and factorial terminal singularities)…
M. GrossMay 3, 1993
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Compactifications of moduli spaces inspired by mirror symmetry
We study moduli spaces of nonlinear sigma-models on Calabi-Yau manifolds, using the one-loop semiclassical approximation. The data being parameterized includes a choice of complex structure on the…
David R. MorrisonApr 23, 1993
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Recovering of curves with involution by extended Prym data
With every smooth, projective algebraic curve C with involution σ:C C without fixed points is associated the Prym data which consists of the Prym variety…
Vassil KanevApr 14, 1993
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Schur quadrics, cubic surfaces and rank 2 vector bundles over the projective plane
A cubic surface in P3 is known to contain 27 lines, out of which one can form 36 Schlafli double - sixes i.e., collections l1,...,l6, l'1,..., l'6\ of 12 lines such that each li…
I. Dolgachev, M. KapranovApr 13, 1993
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Holomorphic Slices, Symplectic Reduction and Multiplicities of Representations
I prove the existence of slices for an action of a reductive complex Lie group on a Kähler manifold at certain orbits, namely those orbits that intersect the zero level set of a momentum map for the…
Reyer SjamaarApr 12, 1993
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What can be computed in algebraic geometry?
This paper is a survey of computational issues in algebraic geometry, with particular attention to the theory of Grobner bases and the regularity of an algebraic variety. 1. A geometric introduction…
Dave Bayer, David MumfordApr 11, 1993
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Refined intersection products and limiting linear subspaces of hypersurfaces
Let X be a hypersurface of degree d in Pn and FX be the scheme of Pr's contained in X. If X is generic, then FX will have the expected dimension (or empty) and its…
Xian WuApr 7, 1993
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Birational Equivalences of Vortex Moduli
We construct a finite dimensional Kaehler manifold with a holomorphic, symplectic circle action whose symplectic reduced spaces may be identified with the tau-vortex moduli spaces (or tau-stable…
S. Bradlow, G. Daskalopoulos, R. WentworthApr 6, 1993
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The Variety of Positive Superdivisors of a Supercurve (Supervortices)
The supersymmetric product of a supercurve is constructed with the aid of a theorem of algebraic invariants and the notion of positive relative superdivisor (supervortex) is introduced. A supercurve…
J. A. Dominguez Perez, D. Hernandez Ruiperez, C. Sancho de SalasMar 29, 1993
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Seshadri constants, gonality of space curves and restriction of stable bundles
We define the Seshadri constant of a space curve and consider ways to estimate it. We then show that it governs the gonality of the curve. We use an argument based on Bogomolov's instability…
Roberto PaolettiMar 28, 1993
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Free pencils on divisors
Let X be a smooth projective variety defined over an algebraically closed field, and let Y in X be a reduced and irreducible ample divisor in X. We give a numerical sufficient condition for a base…
Roberto PaolettiMar 28, 1993
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Theta Functions for (n) versus (n)
Over a smooth complex projective curve C of genus g let (n,d) be the moduli space of semistable bundles of rank n and degree d on C, and (n,L), the moduli space of those bundles…
Ron Donagi, Loring W. TuMar 28, 1993
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Deformations of cones over hyperelliptic curves
We determine the versal deformation of cones, in the simplest case: cones over hyperelliptic curves of high degree. In particular, we show that for degree 4g+4, the highest degree for which…
Jan StevensMar 23, 1993
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Projective varieties with many degenerate subvarieties
We study the problem of classifying the irreducible projective varieties X of dimension n 2 in PN which contain an algebraic family F of dimension h+1 (h<n) of subvarieties…
Emilia MezzettiMar 20, 1993
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