一类流形的刚性定理

本文通过具有良好性质的子流形的存在性，证明了一类流形的一个刚性定理，并得到形如Ｂｏｎｎｅｔ－Ｍｙｅｒｓ定理的推论．我们还指出，在主要定理中全测地子流形的条件一般不能减弱为极小子流形．     

关于四元射影空间的正曲率全复子流形

本文讨论四元射影空间的全复子流形，证明了四元射影空间的正截面曲率紧致全复子流形一定是全测地的。     

双曲空间极小子流形的唯一性

设Ｍ是ｎ维双曲空间Ｈｎ的一个ｋ维的逆紧浸入完备极小子流形，如果Ｍ的渐近边界是一个ｋ－１维球面，则Ｍ是一个ｋ维的全测地子流形．     

关于浸入的Gauss映照和调和映照的几个结果

Obata 在[1]中将欧氏空间中子流形 Gauss 映照的概念推广到单连通完备常曲率空间中的子流形上,并得到了若干结果。这样,利用欧氏空间或球面中子流形的 Gauss 映照来研究子流形性质的方法日趋常见(参见[2],[5],[6],[7])[6]中证明了球面中子流形的 Gauss 映照为全测地时,必为全测地子流形,作为其推广,本文证明了球面中子流     

复空间形式中Lagrange子流形的Casorati曲率不等式（英文）

利用Riemann流形上的Oprea最优化方法,得到了复空间形式中Lagrange子流形关于δ-Casorati曲率δ_c(n-1)的不等式,并证明了等号成立时子流形一定为全测地的.此外,还给出了该不等式的一个应用.     

CP~n 的完备全实具有平行中曲率向量的子流形

本文的目的在于给出一种方法,它可以看作通常的 Bochner 技巧的改进,据此我们证明了 CP~n 的完备全实具有平行中曲率向量和强正截曲率的 n 维子流形是全测地的.     

CP~n 的完备全实具有平行中曲率向量的子流形

本文的目的在于给出一种方法,它可以看作通常的 Bochner 技巧的改进,据此我们证明了 CP~n 的完备全实具有平行中曲率向量和强正截曲率的 n 维子流形是全测地的.     

Sasakian切触度量(κ,μ)-空间中子流形的分类

特征矢量场属于某（κ，μ）－幂零分布的切触度量流形称为切触度量（κ，μ）空间，本文中我们证明了当κ^2 μ^2≠0时，一个非Sasakian切触度量（κ，μ）－空间中的任何子流形要么是不变的全测地子流形。要么为反不变子流形。     

局部对称Bochner-Kaehler流形及其Kaehler子流形

本文给出局部对称的Bochner-Kaehler流形的Riemann结构以及它的Kaehler子流形为全测地子流形的几个Pinching条件,推广了关于复射影空间的Kaehler子流形的相应定理。     

Sasakian子流形的谱几何

本文讨论了 Ｓａｓａｋｉａｎ子流形的谱几何，获得了复 Ｑｕａｄｒｉｃ上圆周丛以及全测地子流形的谱特征．     

Minimal Homogeneous Submanifolds in Euclidean Spaces

We prove that minimal (extrinsically) homogeneous submanifolds of the Euclidean space are totally geodesic. As an application, we obtain that a complex homogeneous submanifold of C ^N must be totally geodesic.     

Automorphisms and a reduction theorem in a Sasakian space form E2m+1(−3)

Summary We construct definitely the automorphism group of a Sasakian space form ¯M=E ^2m+1 (–3) and study the existence of a totally geodesic invariant submanifold of ¯M tangent to a given invariant subspace in the tangent space of ¯M. We also study the Frenet curves in ¯M under a totally contact geodesic immersion of a contact CR-submanifold into ¯M. The purpose of this paper is to prove a reduction theorem of the codimension for a totally contact geodesic, contact CR-submanifold of ¯M.     

A totally geodesic property of Hopf vector fields

We prove that the Hopf vector field is unique among geodesic unit vector fields on spheres such that the submanifold generated by the field is totally geodesic in the unit tangent bundle with Sasaki metric. As an application, we give a new proof of stability (instability) of the Hopf vector field with respect to volume variation using standard approach from the theory of submanifolds and find exact boundaries for the sectional curvature of the Hopf vector field.     

A Pinching Theorem for Minimal Submanifolds in Sphere

§１．ＩｎｔｒｏｄｕｃｔｉｏｎＬｅｔＭｂｅａｎｎ－ｄｉｍｅｎｓｉｏｎａｌｃｌｏｓｅｄｍｉｎｉｍａｌｙｉｍｍｅｒｓｅｄｓｕｂｍａｎｉｆｏｌｄｉｎｔｈｅｕｎｉｔｓｐｈｅｒｅＳｎ＋ｐ，Ｓｔｈｅｓｅｑｕｒｅｏｆｔｈｅｌｅｎｇｔｈｏｆｔｈｅｓｅｃｏｎｄｆｕｎｄ...     

Submanifolds Of Maximal Nullity In Symmetric Spaces

A non-totally-geodesic submanifold of relative nullity n — 1 in a symmetric space M is a cylinder over one of the following submanifolds: a surface F ² of nullity 1 in a totally geodesic submanifold N³ ? M locally isometric to S ²(c) × ? or H ²(c) × ?; a submanifold F ^k+1 spanned by a totally geodesic submanifold F ^k(c) of constant curvature moving by a special curve in the isometry group of M; a submanifold F ^k+l of nullity k in a flat totally geodesic submanifold of M; a curve.     

Twisted dirac operator on minimal submanifolds

Hijazi and Zhang improved Friedrich’s inequality for non-minimal spin submanifolds. Their proof relies on the non-minimality assumption. We use another method to prove that their theorem holds also for minimal submanifolds. As an application, we show that any Kähler manifold can be embedded as a totally geodesic submanifold of its twistor space and apply the above result.     

极小子流形上Laplace算子的谱

本文讨论了Ｓ^ｎ＋ｐ（１）（或ＣＰ^ｎ＋1）中极小子流形上Ｌａｐｌａｃｅ算子的谱，证明了Ｓ^ｎ＋ｐ（１）中全测地极小子流形（或ＣＰ^ｎ＋1中Ｋａｃｈｌｅｒ超曲面）是由作用在ｑ-形式上的Ｌａｐｌａｃｅ算子的谱唯一确定．     

On the Geometry of Lagrangian Submanifolds

We prove that a Lagrangian submanifold passes through each point of a symplectic manifold in the direction of arbitrary Lagrangian plane at this point. Generally speaking, such a Lagrangian submanifold is not unique; nevertheless, the set of all such submanifolds in Hermitian extension of a symplectic manifold of dimension greater than 4 for arbitrary initial data contains a totally geodesic submanifold (which we call the s-Lagrangian submanifold) iff this symplectic manifold is a complex space form. We show that each Lagrangian submanifold in a complex space form of holomorphic sectional curvature equal to c is a space of constant curvature c/4. We apply these results to the geometry of principal toroidal bundles.