Project/Area Number  08454020 
Research Category 
GrantinAid for Scientific Research (B)

Section  一般 
Research Field 
Geometry

Research Institution  KYUSHU UNIVERSITY 
Principal Investigator 
YAMAGUCHI Takao Kyushu University, Graduate School of Mathematics, Professor, 大学院・数理学研究科, 教授 (00182444)

CoInvestigator(Kenkyūbuntansha) 
NISHI Haruko Kyushu University, Graduate School of Mathematics, Research Associate, 大学院・数理学研究科, 助手 (90274430)
YOKOTA Yoshiyuki Kyushu University, Graduate School of Mathematics, Assistant Professor, 大学院・数理学研究科, 講師 (40240197)
KAMATA Masayoshi Graduate School of Mathematics, Kyushu University, Professor, 大学院・数理学研究科, 教授 (60038495)
KATO Mitsuyoshi Graduate School of Mathematics, Kyushu University, Professor, 大学院・数理学研究科, 教授 (60012481)
SHIOHAMA Katsuhiro Graduate School of Mathematics, Kyushu University, Professor, 大学院・数理学研究科, 教授 (20016059)

Project Fiscal Year 
1996 – 1996

Project Status 
Completed(Fiscal Year 1996)

Budget Amount *help 
¥3,900,000 (Direct Cost : ¥3,900,000)
Fiscal Year 1996 : ¥3,900,000 (Direct Cost : ¥3,900,000)

Keywords  Alexandrov spaces / simplicial volume / isometry group / convergence theory / collapsing / アレクサンドロフ空間 / 単体的体積 / 等長変換群 / 収束理論 
Research Abstract 
We have mainly studied the simplicial volumes, the isometry groups, the finiteness property for singular spaces with negative curvature, and established the theory of collapsing for 3manifolds under a lower curvature bound. (1) We have shown that for a generalized psuedomanifold the mass of its fundamental homology class coincides with the total volume, and obtained a relation between the simplicial volume, the curvature bound and the volume. We have also obtained the generalization of GromovThurston inequality for spaces with singularities of codimension one. (2) We have observed the isometry group of an Alexandrov space with curvature bounded above, and proved that the subgroup leaving in variant a compact set is a Lie group. By using this result basically, we have found out some properties of the isometry group similar to those of trees. As an application, we have shown that the isometry group of a simply connected space with nonpositive curvature is a Lie group if the ideal boundary is compact with respect to the Titz metric. (3) In the joint work with Takashi Shioya, we study the collapsing phenomena of threemanifolds under a lower curvature bound. More precisely, by finding out some methods about critical points of distance functions, we have succeeded to describe collapsed manifolds in terms of the limit space. (4) We have shown that the finiteness of homotopy types of spaces with curvature <less than or equal> 1 and with bounds on dimameter and volume. Now we are trying to extend this result to the finiteness of homeomorphisms under an addition hypothesis on the volume of each strata of the dimension stratific
