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1.
If T is an isomorphism of (c0) into C(Ω) (where Ω is a sequentially compact and paracompact space, or a compact metric space in particular), which satisfies the condition ||T||·||T^-1|| ≤ 1 +ε for some ε ∈ (0,1/5), then T/||T|| is close to an isometry with an error less than 9ε. The proof of this article is simple without using the dual space or adjoint operator.  相似文献   

2.
侯吉成 《数学进展》2002,31(3):271-274
设X是拓扑空间,CL(X)表示X的所有非空闭子集的族,本文得到了下述结果:在CL(X)上的Fell-拓扑是伪肾的当且仅当X是feebly-紧或者非局部紧或者非σ-紧,由此得到了对于伪紧性不是闭遗传的两类新的拓扑空间。  相似文献   

3.
项一星 《工科数学》2001,17(1):9-11
本文讨论了Bergman空间L^1a(Ω)中Toeplitz和Hankel算子的W^*紧性,得到与L^2a(Ω)上T-H算子紧性^[4]类似的某些结果。  相似文献   

4.
We study the extension of isometries between the unit spheres of quasi-Banach spaces Lp for 0〈p〈1. We give some sufficient conditions such that an isometric mapping from the the unit sphere of Lp(μ) into that of another LP(ν) can be extended to be a linear isometry defined on the whole space.  相似文献   

5.
LetUbeastandarduniverseandUbeanenlargednonstandarduniversewithrespecttoU.XisatopologicalspacewhichincludedintheindividualsetofU,thatis,XX.Definition1 Foreachx∈X,wedefinem(x)=∩{V:V∈Ix}andcallm(x)themonadofx(Ixistheopenneighborhoodofx).Wewritey≈xfo…  相似文献   

6.
In this paper, we show that if Vo is a 1-Lipschitz mapping between unit spheres of two ALP-spaces with p 〉 2 and -Vo(S1(LP)) C Vo(S1(LP)), then V0 can be extended to a linear isometry defined on the whole space. If 1 〈 p 〈 2 and Vo is an "anti-l-Lipschitz" mapping, then Vo can also be linearly and isometrically extended.  相似文献   

7.
Lina 《东北数学》2004,20(3):271-274
This paper is concerned with the relation between the compactness and sequential compactness in a topological space or a topological group, and show that the compactness and sequential compactness coincide in a topolpgical group with the axiom (A1).  相似文献   

8.
On the Extension of Isometries between Unit Spheres of E and C(Ω)   总被引:8,自引:0,他引:8  
In this paper,we study the extension of isometries between the unit spheres of some Banach spaces E and the spaces C(Ω). We obtain that if the set sm.S1(E) of all smooth points of the unit sphere S1(E) is dense in S1(E),then under some condition,every surjective isometry V0 from S1(E) onto S1(C(Ω)) can be extended to be a real linearly isometric map V of E onto C(Ω).From this resultwe also obtain some corollaries. This is the first time we study this problem on different typical spaces,and the method of proof is also very different too.  相似文献   

9.
In this paper, we study the extension of isometries between the unit spheres of normed space E and lP(p 〉 1). We arrive at a conclusion that any surjective isometry between the unit sphere of normed space lP(p 〉 1) and E can be extended to be a linear isometry on the whole space lP(p 〉 1) under some condition.  相似文献   

10.
邹进 《数学季刊》1996,11(2):43-48
TheCharacterizationsofWeighted H~p(w)SpacesontheCertainGroupsZouJin(邹进)(Leshan,TheachersCollege,China)Abstract:TheweightedHP(?..  相似文献   

11.
本文揭示了L^p空间中一类C0半群稳定性的特征,从而获得一个实际问题中较易检验的稳定性条件,作为应用,本文研究了中子迁移系统的稳定性。  相似文献   

12.
定义L-fuzzy非负扩充实直线R+(L)与R+(L)值半连续映射,证明在一个L-core紧的L-fuzzy拓扑空间(L^x,δ)上的R+(L)值下半连续映射的全体关于点式序,加法运算与数乘运算的构成一个连续d锥,推广了文献[6]中的结果。  相似文献   

13.
武三星  张静 《数学季刊》2008,23(1):89-95
This paper considers the existence problem of an elliptic equation.which is equivalent to the prescribing conformal Gaussian curvature problem on R2.An existence result is pried.In particular,K(x)is allowed to be unbounded above.  相似文献   

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