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1999 Fiscal Year Final Research Report Summary

Differential Geometry and Information Geometry II

Research Project

Project/Area Number 10440022
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Geometry
Research InstitutionYamaguchi University

Principal Investigator

SHIMA Hirohiko  Yamaguchi University, Mathematics, Professor, 理学部, 教授 (70028182)

Co-Investigator(Kenkyū-buntansha) KOMIYA Katsuhiro  Yamaguchi University, Mathematics, Professor, 理学部, 教授 (00034744)
INOUE Toru  Yamaguchi University, Mathematics, Professor, 理学部, 教授 (00034728)
NAITOH Hiroo  Yamaguchi University, Mathematics, Professor, 理学部, 教授 (10127772)
HATAYA Yasushi  Yamaguchi University, Mathematics, Assistant, 理学部, 助手 (20294621)
NAKAUCHI Nobumitsu  Yamaguchi University, Mathematics, Associate Professor, 理学部, 助教授 (50180237)
Project Period (FY) 1998 – 1999
KeywordsHessian manifold / Kahler manifold / dual connection / Codazzi structure / information geometry / affine differential geometry
Research Abstract

A pair (D, g) of an affine connection D and a Riemann metric g is said to be a Codazzi structure if g satisfies Codazzi equattion with respect to D. For a Codazzi structure (D, g) , D is flat if and only if (D, g) is a Hessian structure, that is, g is locally expressed by a Hessian with respect to affine coordinate systems for D. Hessian (Codazzi) structures are deeply connected with Kahler geometry and affine differential geometry, and play important, essential and central roles in information geometry. In this project we engaged in fundamental researches for Hessian (Codazzi) structures from both differential geometric and information geometric viewpoints, and obtained the following results.
1 We relate the existence of invariant projectively flat affine connections to that of certain affine representation of Lie algebras. Using such affine representation we proved :
(1) A homogeneous space G/K admits an invariant projectively flat affine connection if and only if G/K has an equivariant centro-affine hypersurface immersion.
(2) There is a bijective correspondence between semi-simple symmetric spaces with invariant projectively flat affine connections and central-simple Jordan algebras.
(3) A homogeneous space admits an invariant Codazzi structure of constant curvature c=0 if and only if it has an equvariant immersion of codimension 1 into a certain homogenous Hessian manifolds.
2 For a linear mapping ρ of a domain Ω into the space of positive definite symmetric matrices we conatructed an exponential family of probability distributions parametrized by the elements in RィイD1nィエD1×Ω, and studied a Hessian structure on RィイD1nィエD1×Ω given by the exponential family. Using ρ we introduced a Hessian structure on a vector bundle over a compact hyperbolic affina manifold and proved a certain vanishing theorem.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] Hirohiko Shima: "Homogeneous space with invariant projectively tlat affine connections"Trans.American Math.Soc.. 351・12. 4713-4726 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Hirohiko Shima: "Imvariant projectively tlat wnnecticns and its applications"Lobachevskii Journal of Math.. 4. 99-107 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Hirohiko Shima: "Geometry associated with noemal distributions"Osaka Journal of Math.. (発表予定).

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Hiroo Naitoh: "Grassmann geometries on compact symmetric spaces of classical type"Japanese J.Math.. 26・2. (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Nobumitsu Nakauchi: "A Liouville type theorem for p-hermonic maps"Osaka Journal of Math.. 35. 303-312 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Shigeo Kawai: "On the existence of n-hermonic spheres"Comp.Meth.. 117. 33-43 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] SHIMA, Hirohiko: "Geometry associated with normal distributions"Osaka J. Math.. (to appear).

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] SHIMA, Hirohiko: "Homogeneous spaces with invariant projectively flat affine connections"Trans. American Math. Soc.. 351-12. 4713-4726 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] SHIMA, Hirohiko: "Invariant projectively flat connections and its applications"Lobachevskii J. Math.. 4. 99-107 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] NAITOH, Hiroo: "Grassman geometry on compact symmetric spaces of classical type"Japanese J. Math.. 26-2. (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] NAKAUCHI, Nobumitsu: "A Liouville type theorem for p-harmonic maps"Osaka J. Math.. 35. 303-312 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] NAKAUCHI, Nobumitsu: "On the existence of n-harmonic spheres"Comp. Math.. 117. 33-43 (1999)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2001-10-23  

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