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1.
该文主要讨论单位球面中具有Ricci曲率拼挤的极小子流形的F调和映射的不稳定性,得到的结果推广了文[1]中相应的结果.  相似文献   

2.
本文讨论了黎曼流形的极小子流形与调和映射的关系,指出了这二类变分问题的一致性和区别。  相似文献   

3.
本文考察复 Grassmann 流形作为单位球面内的等距嵌入子流形的几何性质,并且给出了从体积有限的 Riemann 流形到复 Grassmann 流形的一个调和映射为常值映射的条件。  相似文献   

4.
Grassmann流形作为子流形的微分几何   总被引:1,自引:0,他引:1  
陈维桓 《数学学报》1988,31(1):46-53
本文把Grassmann流形看作等距地嵌入在单位球面内的子流形,建立它的基本公式,然后证明它的极小性质.此外,利用这种嵌入把欧氏空间中子流形的Gauss映射看作到单位球面内的映射,并建立了这种广义的Gauss映射是调和映射的条件.  相似文献   

5.
在Hermitian流形上,将Bochner公式推广到了复向量丛上,并以此得到了Hermitian流形之间的调和映射的解析性质.  相似文献   

6.
周春琴 《数学学报》1998,41(2):327-336
分别考虑了映入球面及紧致的齐性Riemannian空间的弱P-调和映射流;通过球面及齐性Riemannian空间的对称性质,证明了弱P-调和映射流的紧性性质.  相似文献   

7.
研究了拟常曲率空间中的2-调和子流形与极小子流形.首先得到了拟常曲率空间中具有平行平均曲率的2-调和子流形为极小子流形的一个较好的充分条件,然后得到了2-调和超曲面与极小超曲面在一定条件下是等价的结论.  相似文献   

8.
本文将对丘成桐第一特征值猜想的提出与发展,以及等参情形的完全解决进行综述,并介绍其与Lawson猜想的关系.进一步,本文还计算了等参焦流形(球面的极小子流形)的第一特征值,并提出丘成桐猜想的高余维情形的推广问题.  相似文献   

9.
1.二个同维数的光滑流形之间,映射的体积元之比是映射的最简单、最重要的度量不变量。陈省身教授[1]讨论了同维数 Hermitian 流形间和乐映射的减小体积性质,推广了著名的 Schwarz 引理,陈省身和 Goldberg[2]又对同维数实黎曼流形间的调和映射作了研究,得到若干减小体积的定理。本文将考虑二个不同维数的黎曼流形间的调和映射,以便推广[2]中有关的结论。  相似文献   

10.
刘宇红  朱宏 《数学杂志》2007,27(6):735-737
本文研究了球面到紧致光滑流形的连续映射的性质.利用Brouwer映射度理论和微分拓扑的基本方法,得到了Munkholm型定理.  相似文献   

11.
Minimal graphs     
Elementary properties of harmonic maps between Riemannian manifolds are interpreted via their graphs, viewed as nonparametric minimal submanifolds (Proposition 1). Then examples, are given of nonparametric submanifolds of compact Riemannian manifolds which cannot be deformed-through nonparametric submanifolds-to nonparametric minimal submanifolds (Propositions 2 and 4).  相似文献   

12.
QUANTUM PHENOMENON OF THE ENERGY DENSITY OF A HARMONIC MAP TO A SPHERE   总被引:1,自引:0,他引:1  
This paper proves that if the energy density of a harmonic map to a unit sphere varies between two successive half eigenvalues, then it must be one of them. Applying this result to the Gaussian maps of some submanifolds, the quantum phenomena of the square length of the second fundamental forms of these submanifolds is obtained. Some related topics are discussed in this note.  相似文献   

13.
Monotonicity formulae play a crucial role for many geometric PDEs, especially for their regularity theories. For minimal submanifolds in a Euclidean ball, the classical monotonicity formula implies that if such a submanifold passes through the centre of the ball, then its area is at least that of the equatorial disk. Recently Brendle and Hung proved a sharp area bound for minimal submanifolds when the prescribed point is not the centre of the ball, which resolved a conjecture of Alexander, Hoffman and Osserman. Their proof involves asymptotic analysis of an ingeniously chosen vector field, and the divergence theorem.In this article we prove a sharp ‘moving-centre’ monotonicity formula for minimal submanifolds, which implies the aforementioned area bound. We also describe similar moving-centre monotonicity formulae for stationary p-harmonic maps, mean curvature flow and the harmonic map heat flow.  相似文献   

14.
著名的Yau 猜想断言单位球面中的紧致嵌入极小超曲面的Laplace 算子的第一特征值等于其维数. 近年来有许多几何学家致力于对Yau 猜想的研究, 但是到目前为止, 已有的结论只是一些关于第一特征值估计的不等式. 作为本文的一个主要结果, 本文证明了对于单位球面中的等参极小超曲面,Yau 猜想是正确的. 进一步地, 对于等参超曲面的焦流形(实际上是球面的极小子流形), 本文还证明了在一定维数条件下, 它的第一特征值也是其维数.
作为本文的第二个主要结果, 以著名的Schoen-Yau-Gromov-Lawson 的关于数量曲率的手术理论为出发点, 本文在一个Riemann 流形的嵌入超曲面处作手术, 构造了一个新的具有丰富几何性质的流形, 称为double 流形. 特别地, 本文在单位球面的极小等参超曲面处实行了这一手术, 发现得到的double 流形不仅有很复杂的拓扑(但其示性类有精确描述), 还存在数量曲率为正的度量, 更重要的是保持了等参叶状结构.
比Willmore 曲面更广泛的定义是Willmore 子流形, 即Willmore 泛函在球面中的的极值子流形.单位球面中的Willmore 子流形的例子在已有文献中是非常罕见的. 作为本文的另外两个主要结果, 通过深入挖掘单位球面上的OT-FKM- 型等参函数的焦流形的性质, 本文发现其极大值对应的焦流形是单位球面的一系列Willmore 子流形; 之后, 本文用几何办法统一证明了单位球面中具有4 个不同主曲率的等参超曲面的焦流形都是单位球面的Willmore 子流形. 这些新的Willmore 子流形是极小的,但一般不是Einstein 的.  相似文献   

15.
In this paper, the authors present a method to construct the minimal and ${\rm H}$-minimal Lagrangian submanifolds in complex hyperquadric $Q_n$ from submanifolds with special properties in odd-dimensional spheres. The authors also provide some detailed examples.  相似文献   

16.
We study harmonic sections of the normal bundles for submanifolds. Especially, the stability of certain harmonic sections of the normal bundles for compact submanifolds in the spheres are considered.  相似文献   

17.
The main purpose of this article is to generalize a theorem about the size of minimal submanifolds in Euclidean spaces. In fact, we state and prove a non-existence theorem about harmonic maps from a stochastically complete manifold into a cone type domain. The proof is based on a generalized version of the maximum principle applied to the Lapalace-Beltrami operator on Riemannian manifolds. Received: 2 August 2007, Revised: 14 April 2008  相似文献   

18.
We prove that a complete non-compact submanifold in a complete manifold of partially non-negative sectional curvature has only one end if the Sobolev inequality holds on it and if its total curvature is not very big by showing a Liouville theorem for harmonic maps and by using a existence theorem of constant harmonic functions with finite energy. We also generalize a result by Cao–Shen–Zhu saying that a complete orientable stable minimal hypersurface in a Euclidean space has only one end to submanifolds in manifolds of partially non-negative sectional curvature. Some related results about the structure of the same kind of submanifolds are also obtained.  相似文献   

19.
A general Liouville-type result and a corresponding vanishing theorem are proved under minimal regularity assumptions. The latter is then applied to conformal deformations of stable minimal hypersurfaces, to the L2 cohomology of complete manifolds, to harmonic maps under various geometric assumptions, and to the topology of submanifolds of Cartan-Hadamard spaces with controlled extrinsic geometry.  相似文献   

20.
We investigate properties of harmonic Gauss maps and their applications to Lawson-Osserman’s problem, to the rigidity of space-like submanifolds in a pseudo-Euclidean space and to the mean curvature flow.  相似文献   

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