Semi-Parallel, Semi-Symmetric Immersions and Chen’s Equality

Recently, B. Y. Chen introduced a new invariant δ(n₁,n₂,…,n_k) of a Riemannian manifold and proved a basic inequality between the invariant and the extrinsic invariant if, where H is the mean curvature of an immersion Mⁿ in a real space form R^m(ε) of constant curvature ε. He pointed out that such inequality also holds for a totally real immersion in a complex space form. The immersion is called ideal (by B. Y. Chen) if it satisfies the equality case of such inequality identically. In this paper we classify ideal semi-parallel immersions in an Euclidean space if their normal bundle is flat, and prove that every ideal semi-parallel Lagrangian immersion in a complex space form is totally geodesic, moreover this result also holds for ideal semi-symmetric Lagrangian immersions in complex projective space and hyperbolic space.     

局部凸空间上检验函数与广义函数空间的嵌入定理及其应用

设Y是局部凸向量空间,其上装配有GaussianRadon测度γ．A（Y）（或ε（Y）是Y上检验函数空间（或με（Y）是相应的分布函数空间·我们证明了：（或με（Y）,并由此得到μA（Y）（或με（Y））上的Fourier变换公式.其中“*”表示复共轭算子,“”表示连续稠线性嵌入.进一步还得到了A（Y）（或ε（Y））上无穷维伪微分算子A是L2（Y,γ）上连续的充要条件是其共轭算子A’满足A’（L2（Y,γ）L2（Y,γ）．     

Characterization and properties of extreme operators intoC(Y)

LetE be a real (or complex) Banach space,Y a compact Hausdorff space, andC(Y) the space of real (or complex) valued continuous functions onY. IfT is an extreme point in the unit ball of bounded linear operators fromE intoC(Y), then it is shown thatT ^* maps (the natural imbedding inC(Y) ^* of)Y into the weak ^*-closure of extS(E ^*), provided thatY is extremally disconnected, orE=C(X), whereX is a dispersed compact Hausdorff space.     

SLANT IMMERSIONS OF COMPLEX SPACE FORMS AND CHEN＇S INEQUALITY

A submanifold in a complex space form is called slant it it has constant Wirtinger angles. B, Y, Chen and Y. Tazawa proved that there do not exist minimal proper slant surfaces in CP^2 and CH^2. So it seems that the slant immersion has some interesting properties. The authors have great interest to consider slant immersions satisfying some additional conditions, such as unfull first normal bundles or Chen‘s equality holding. They prove that there do not exist n-dimensional Kaehlerian slant immersion sin CP^n and CH^n with unfull first normal bundles. Next, it is seen that every Kaehlerian slant submanifold satisfying an equality of Chen is minimal which is similar to that of Lagrangian immersions. But in contrast, it is shown that a large class of slant immersions do not exist thoroughly. Finally, they give an application of Chen‘s inequality to general slant immersions in a complex projective space, which generalizes a result of Chen.     

关于有界线性算子的非紧测度的若干性质

利用非紧测度在商空间B(X,Y)/K(X,Y)上构造了一个范数,指出这一范数可由B(X,Y)上的某一范数生成.并且X或Y是Hilbert空间时,B(X,Y)/K(X,Y)上赋于这种范数时是完备的.另外,还建立了非紧测度与熵数,近似数之间的一些联系.     

关于S^n＋p和CP^n＋p中的极小子流形

本文改进了分别由Ｓ．Ｔ．Ｙａｕ，Ａ．Ｒｏｓ及沈一兵给出的关于单位球面Ｓｎ＋ｐ的极小流形和复射影空间ＣＰ＾ｎ＋ｐ的Ｋａｅｈｌｅｒ子流形及全实极小子流形的截面曲率的Ｐｉｎｃｈｉｎｇ常数。     

Invariant Submanifolds of Real Hypersurfaces of Complex Manifolds

Real hypersurfaces of a complex manifold admit a naturally induced almost contact structure F′ from the almost complex structure of the ambient manifold. We prove that for any F′-invariant submanifold M of a geodesic hypersphere in a non-flat complex space form and of a horosphere in a complex hyperbolic space, its second fundamental form h satisfies the condition h(FX,Y ) - h(X, FY) = g(FX, Y )h, X,Y ? T(M), 0 1 h ? T^{^}(M){h(FX,Y ) - h(X, FY) = g(FX, Y )\eta, X,Y \in T(M), 0 \ne \eta \in {T^\perp}(M)}, which has been considered in [2] and [3].     

Topological continuous convergence

Let X be a limit space, Y a topological space. We show that c(X,Y), the limitierung of continuous convergence on LIM(X,Y), is topological whenever X is basic locally compact. For regular Y, local compactness of X is sufficient. In both cases, c(X,Y) coincides with the compact-open topology. If X satisfies a certain regularity condition, the fact that c(X,Y) is topological implies, conversely, that X is (basic) locally compact.The author would like to thank S. Weck for some inspiring discussions.     

多复变数全纯映射精细的Bohr定理

本文首先建立不依赖自同构从复Banach空间平衡域到Cn单位多圆柱上一定限制条件下全纯映射精细的范数型Bohr定理及复Banach空间X上单位球到复Banach空间Y上单位球全纯映射精细的泛函型Bohr定理.其次,给出有界对称域上全纯映射精细的Bohr定理.最后,得到J*代数单位球上全纯映射精细的Bohr定理.所得结果将一维的Bohr定理推广至高维.     

A Note on Isomorphic Groups and Nonhomeomorphic Spaces

Given a Tychonov space X we can construct another space Y with the same group of homeomorphisms such that X and Y are, in some sense, "almost arbitrarily different".     

Operators with connected spectrum + compact operators = strongly irreducible operators

Herrero’s conjecture that each operator with connected spectrum acting on complex, separable Hilbert space can be written as the sum of a strongly irreducible operator and a compact operator is proved. Jiang, C. L., Power, S., Wang, Z. Y., Biquasitriangular + small compact = strongly irreducible,J. London Math., to be published.     

Tubenumgebungen Steinscher Räume

Let X be a complex space and YX a closed analytic subspace. If Y is Stein then for every compact subset KY one can find arbitrarily small Stein open neighbourhoods of K in X.     

Interpolation Functors In Weak-Type Interpolation

For interpolation in the diagonal case, i.e. with respect to the two couples (X, X) and (Y, Y), there exists a natural relation between weak-type and strong-type interpolation. Indeed, weak-type interpolation is related to the “M-couples” (ΛX, MX) and (ΛY, MY) of the Lorentz spaces of X and Y. Since ΛZ ? MZ for any space Z, any weak-type interpolation space also has the (strong-type) interpolation property for the “Λ-couples” (ΛX, ΛX) and (ΛY, ΛY). In this paper a scale ${cal G}, c>0$ , of interpolation functors with respect to the Λ-couples is introduced such that all generated interpolation spaces (also) have the weak-type interpolation property. Moreover, we will show that a space is a weak interpolation space if and only if it is generated by one of these functors.     

Asymptotically Isometric Copy of lβ (0 ＜β ＜ 1) in Spaces of Bounded Linear Operators

Assume X is a normed space, every x* ∈ S(X*) can reach its norm at some point in B(X), and Y is a β-normed space. If there is a quotient space of Y which is asymptotically isometric to lβ, then L(X, Y) contains an asymptotically isometric copy of lβ. Some sufficient conditions are given under which L(X, Y) fails to have the fixed point property for nonexpansive mappings on closed bounded β-convex subsets of L(X, Y).     

Discreteness of subgroups of PU(2,1) with regular elliptic elements

In [Y.-P. Jiang, S. Kamiya, J.R. Parker, Jøgensen’s inequality for complex hyperbolic space, Geometriae Dedicate 97 (2003) 55-80], Jiang et al. provided Jørgensen’s inequality for non-elementary group of isometries of complex hyperbolic space generated by two elements, one of which is loxodromic or boundary elliptic. In this paper, we give analogues of Jørgensen’s inequality for the subgroup generated by two elements, but one of which is regular elliptic.     

Quotienten komplexer Mannigfaltigkeiten nach spiegelungsfreien Gruppen

There is given a necessary and sufficient (global) topological condition on a complex space X for the existence of a local finite analytic mapping YX with Y a manifold and branched locus of codimension>1.     

点是Gδ-集的∑*-空间的构成定理

在林寿与我最近合作的一篇文章中指出了∑*-空间的构成定理需重新考虑.本文就是要证明在空间X的每个点是Gδ-集的条件下该构成定理是成立的,所得的结论是:X是T1且每个点是Gδ-集的∑*-空间,如果f:X→Y是闭的满连续映射,则在Y中有一σ-闭离散子空间Z,使得对每个y∈Y\Z,f-1(y)是X的w1-紧子空间.为得到该主要结果,本文证明了若空间X是每个点是Gδ-集的次亚紧空间.则X中的每个闭离散子集是X中的Gδ-集.     

函数空间上的模糊线性拓扑

本文给出了模糊拓扑向量空间（Ｘ，Ｗ）到（Ｙ，Ｊ）的函数族Ｆ上的模糊线性拓扑，证明了若值域空间（Ｙ，Ｊ）是（Ｑ）型的、局部凸的模糊拓扑向量空间，则（Ｆ，），也是型的、局部凸的模糊拓扑向量空间。     

拓扑半共轭关系是个预序但不是偏序

本短文指出，存在着紧致连通空间Y及同胚f：Y→Y，g：Y→Y使得f拓扑半共轭于g，g也拓扑半共轭于f，但f与g不拓扑共轭．据此说明了拓扑半共轭关系是个预序但不是偏序。     

Ein beweis des Grauertschen bildgarbensatzes nach ideen von B. Malgrange

In 1960, H. Grauert proved the following coherence theorem [2]: Let X, Y be complex spaces and : X Y a proper holomorphic map. Then, for every coherent analytic sheaf J on X, all direct image sheaves Rⁿ*J are coherent. We give a new proof of this theorem, based on ideas of B. Malgrange. This proof does not use induction on the dimension of the base space Y and can be generalized to relative-analytic spaces X Y where Y belongs to a bigger category of ringed spaces, which contains in particular all complex spaces and differentiable manifolds.