Project/Area Number  09440035 
Research Category 
GrantinAid for Scientific Research (B)

Section  一般 
Research Field 
Geometry

Research Institution  Yamaguchi University 
Principal Investigator 
NAITOH Hiroo Faculty of Science, Yamaguchi University Professor, 理学部, 教授 (10127772)

CoInvestigator(Kenkyūbuntansha) 
菊政 勲 山口大学, 理学部, 助教授 (70234200)
片山 寿男 山口大学, 理学部, 教授 (00043860)
INOUE Toru Faculty of Science, Yamaguchi University Professor, 理学部, 教授 (00034728)
NAKAUCHI Nobumitsu Faculty of Science, Yamaguchi University Associate Professor, 理学部, 助教授 (50180237)
SHIMA Hirohiko Faculty of Science, Yamaguchi University Professor, 理学部, 教授 (70028182)
KATO Takao Faculty of Science, Yamaguchi University Professor, 理学部, 教授 (10016157)
渡邉 正 山口大学, 教育学部, 教授 (10107724)
KOMIYA Katsuhiro Faculty of Science, Yamaguchi University Professor, 理学部, 教授 (00034744)

Project Fiscal Year 
1997 – 1998

Project Status 
Completed(Fiscal Year 1998)

Budget Amount *help 
¥6,900,000 (Direct Cost : ¥6,900,000)
Fiscal Year 1998 : ¥3,200,000 (Direct Cost : ¥3,200,000)
Fiscal Year 1997 : ¥3,700,000 (Direct Cost : ¥3,700,000)

Keywords  symmetric space / submanifold / Grassmann geometry / totally geodesic submanifold / Lie algebra / partial differential equation of 1st order / 対称空間 / 部分多様体 / グラスマン幾何 / 全測地的部分多様体 / リー代数 / 一階偏微分方程式系 
Research Abstract 
This investigation is on the submanifold theory of compact simply connected Riemannian symmetric spaces. We study it by using a Grassmann geometry, introduced by R.Harvey and H.B.Lawson in their consideration of calibrated geometry. Particularly we study a Grassmann geometry of orbital type. The main subjects treated here are the following three : (1) the existence problem, (2) the classification, and (3) applications for submanifold theory. For each subject, we have obtained the following results and foreknowledges : (1) Generally, given a Grassmann geometry of orbital type, the existence problem whether the geometry admits associated submanifolds or not is equivalent to the local solvability of a certain system of 1st order PDE's defined on the isometry group of the ambiant symmetric space. Moreover, under this equivalence, the geometrical property of an associateed submanifold, what is called the 2nd fundamental form, is charac terized in terms of a solution of the system of 1st order PDE's. Also, for the orbital Grassmann geometries of curves and the ones of real hypersurfaces, the existence problem has been solved affirmatively, and for the orbital Grassmann geometries of strongly curvatureinvariant type the geometric structure of associated submanifolds has been clarified. (2) Among Grassmann geometries of orbital type, there exists an important class, what is called of totally geodesic type. The Grassmann geometries of strongly curvatureinvariant type, described above, constitute a subclass of the class of totally geodesic type. We have completed the classification of this subclass, by using such finite diagrams as Dynkin's diagrams. We suppose that this method also is useful even for the cases of general totally geodesic type. (3) As applications of Grassmann geometry, we have the classification of symmetric submanifolds and the generalization of Gauss mappings. We suppose that these notions are also very useful for the submanifold theory of symmetic spaces.
