Mostrando recursos 1 - 20 de 159

  1. Equivariant Elliptic Genera and Local McKay Correspondences

    Waelder, Robert
    In this paper we prove an equivariant version of the McKay correspondence for the elliptic genus on open varieties with a torus action. As a consequence, we will prove the equivariant DMVV formula for the Hilbert scheme of points on C2.

  2. Differential Gerstenhaber Algebras Associated to Nilpotent Algebras

    Cleyton, Richard; Poon, Yat-Sun
    This article provides a complete description of the differential Gerstenhaber algebras of all nilpotent complex structures on any real six-dimensional nilpotent algebra. As an application, we classify all pseudo-Kählerian complex structures on six-dimensional nilpotent algebras whose differential Gerstenhaber algebra is quasi-isomorphic to that of the symplectic structure. In a weak sense of mirror symmetry, this gives a classification of pseudo-Kähler structures on six-dimensional nilpotent algebras whose mirror images are themselves.

  3. On the Crepancy of the Gieseker-Uhlenbeck Morphism

    Qin, Zhenbo; Zhang, Qi
    The Gieseker-Uhlenbeck morphism from the moduli space of Gieseker semistable rank-2 sheaves over an algebraic surface to the Uhlenbeck compactification was constructed by Jun Li. We prove that if the anti-canonical divisor of the surface is effective and the first Chern class of the semistable sheaves is odd, then the Gieseker-Uhlenbeck morphism is crepant

  4. Comparing Corresponding Dihedral Angles on Classical Geometric Simplices

    Au, Thomas Kwok-keung; Luo, Feng; Stong, Richard
    In this article, we prove a theorem comparing the dihedral angles of simplexes in the hyperbolic, spherical and Euclidean geometries.

  5. A Rigidity Result for p-divisible Formal Groups

    Chai, Ching-Li

  6. Groups with Essential Dimension One

    Chu, Huah; Hu, Shou-Jen; Kang, Ming-chang; Zhang, Jiping
    Denote by edK(G) the essential dimension of G over K. If K is an algebraically closed field with char K = 0, Buhler and Reichstein determine explicitly all finite groups G with edK(G) = 1. We will prove a generalization of this theorem when K is an arbitrary field.

  7. Integral Canonical Models of Unitary Shimura Varieties

    Vasiu, Adrian
    We prove the existence of integral canonical models of unitary Shimura varieties in arbitrary unramified mixed characteristic. Errata to [Va1] are also included.

  8. Complex Product Manifolds Cannot be Negatively Curved

    Seshadri, Harish; Zheng, Fangyang
    We show that if M = X × Y is the product of two complex manifolds (of positive dimensions), then M does not admit any complete Kähler metric with bisectional curvature bounded between two negative constants. More generally, a locally-trivial holomorphic fibre-bundle does not admit such a metric.

  9. nstantons and Branes in Manifolds with Vector Cross Products

    Lee, Jae-Hyouk; Leung, Naichung Conan

  10. Transformations of Flat Lagrangian Immersions and Egoroff Nets

    Terng, Chuu-Lian; Wang, Erxiao

  11. A Proof of Shelah's Strong Covering Theorem for Pkλ

    Shioya, Masahiro

  12. A Note on Complex Monge-Ampère Equation in Stein Manifolds

    Bahraini, Alireza
    We study in this note the Dirichlet problem for complex Monge-Ampère equation in compact Stein manifolds with boundary. As far as we know among the global results for Monge- Ampère equations, compact manifolds with boundary have been less discussed.

  13. Palindromic Braids

    Deloup, Florian; Garber, David; Kaplan, Shmuel; Teicher, Mina

  14. On First Order Congruences of Lines in P4 with Generically Non-reduced Fundamental Surface

    De Poi, Pietro

  15. Toric Degenerations of GIT Quotients, Chow Quotients, and M0,n

    Hu, Yi

  16. Rigidity of Cylinders without Conjugate Points

    Koehler, Henrik
    During the last decades, several investigations were concerned with rigidity statements for manifolds without conjugate points (some results can be found in the references). Based on an idea by E. Hopf, K. Burns and G. Knieper proved that cylinders without conjugate points and with a lower sectional curvature bound must be flat if the length of the shortest loop at every point is globally bounded. ¶ The present article reduces the last condition to a limit for the asymptotic growth of loop-length as the basepoint approaches the ends of the cylinder (Thm. 18). Along the way, the shape of cylinders without conjugate points is characterized: The loop-length...

  17. Geometric Hamiltonian Structures on Flat Semisimple Homogeneous Manifolds

    Beffa, G. Mari

  18. Modifying hyperkähler manifolds with circle symmetry

    Dancer, Andrew; Swann, Andrew
    A construction is introduced for modifying hyperkähler manifolds with tri-Hamiltonian circle action, that in favourable situations increases the second Betti number by one. This is based on the symplectic cut construction of Lerman. In 4 or 8 dimensions the construction may be interpreted as adding a D6-brane. A number of examples are given and a generalisation to three-Sasaki geometry discussed.

  19. Floer cohomology and disc instantons of Lagrangian torus fibers in Fano toric manifolds

    Cho, Cheol-Hyun; Oh, Yong-Geun

  20. Integral bases for an infinite family of cyclic quintic fields

    Eloff, Daniel; Spearman, Blair K.; Williams, Kenneth S.
    An explicit integral basis is given for infinitely many cyclic quintic fields.

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