关于紧邻域扩充性质的等价条件及其应用

本文刻画了紧邻域扩充性质的等价条件，由此条件得到如果Ｘ是具有紧邻域扩充性质的可度量化的拓扑空间，则Ｆ_ｋ（Ｘ）＝｛Ａ?Ｘ：｜Ａ｜≤ｋ｝也具有紧邻域扩充性质，此处Ｆ_ｋ（Ｘ）上的拓扑是由Ｈａｕｓｄｏｒｆ度量所诱导出的拓扑     

绝对可和算子的一分解

若 Banach 空间 X 不具备 Radon-Nikodym 性质,则绝对可和算子 T:C(S)→X 对某些紧 Hausdorff 空间 S 而言就不必是核算子本文把绝对可和算子 T:C(S)→X(B(S)→X)分解成为,T=T_Ⅰ+T_Ⅱ9,其中 T_Ⅰ是核算子,T_Ⅱ在定义域的某一子空间上是零算子.这种分解的一个明显好处是:绝对可和算子近似于核算子的程度通过定义域的结构     

L—FUZZY拓扑空间中几种紧性

本文在L－fuzzy拓扑空间中引进了几种不同的具有有限交性质的闭集族，并以此刻划了良紧空间、强F紧空间和F紧空间的特征。另外，对F紧空间还给出了复盖式以及远域族式的刻划。     

关于凸子集和（绝对）收缩核

讨论了线性度量空间中凸子集在什么情况下为该空间的收缩核，以及在什么情况下为绝对收缩核。     

局部Cauchy列和局部完备性的性质

利用完备化的方法,给出了局部凸分离空间（X,T）中序列{xn}是局部Cauchy列当且仅当存在单调增且趋于正无穷大的正实数列{an},使得min{an,am}（xn-xm）→0（m,n→∞）,并得到局部凸分离空间（X,T）是局部完备的当且仅当X中每个丁局部Cauchy列的绝对凸闭包是丁紧的,以及一些局部完备性的相关性质．     

半拓扑空间的性质

§1 引 言 本文继续〔1〕、〔2〕关于半拓扑空间性质的讨论,给出了半拓扑空间中闭图象的等价刻划并将Franklin,S.关于拓扑空间紧性的特征定理推广到O-ST空间类。另外本文还引入了邻域子空间及局部邻域紧空间的概念并对其进行了初步讨论。这些概念及其讨论进一步完善了半拓扑空间理论。     

Banach—Saks性质与近一致凸、紧安全凸性

本文通过引入B-NUC Banach空间及WB性质,进一步研究Banach-Saks性质（BSP）与近一致凸及紧完全凸性之间的关系。得到以下主要结果。1）Banach空间X具有WB性质当且仅当X具有WBanach-Saks性质（WBSP）;2）X是B-NUC空间当且仅当X是具BSP的NUC空间;3）若X具BSP及（H）性质,则X是CωR空间（紧完全ω-凸空间）。     

L-fuzzy拓扑空间中的强Lindelf性质

本文在L-fuzzy拓扑空间中引进了强Lindelof性质以及与之有关的一些概念,给出了强Lindelof空间的等价刻划,证明了强Lindelof性质对闭子集遗传,是弱拓扑不变性质;当(L~x,ωL(?))具有强远域族性质时,(L~x,ωL(?))是强Lindelof空间当且仅当(X,(?))是Lindelof空间。此外,讨论了强Lindelof性质与良紧性、仿紧性之间的关系。     

S(3)-空间的θ2-绝对

通过在S（3）－空间中引入概念θ^2－绝对，建立了S（2）－闭的S（3）－空间与紧空间的联系，并且给出了几个与之相关的性质。     

拓扑线性空间中的Drop定理与Drop性质

给出了拓扑线性空间中的一个Drop定理.利用此Drop定理,证明了拓扑线性空间中的每个序列紧凸集具有Drop性质;每个可数紧闭凸集具有拟Drop性质.而且结出了拓扑线性空间中Drop性质和拟Drop性质的序列流特征.也讨论了Drop性质和拟Drop性质与泛函取极值之间的联系.     

關於Borsuk的絕對同倫擴充性質的討論

<正> 序言.在同倫論中,常常需要考慮滿足這種性質的拓撲空間X設Y為任意的一個正規空間,B為Y的任何一個非空閉集,任何一個由B×(0,1)+Y×(0)到X的映像都可以扩充為一個由Y×(0,1)到X的映像,我們稱這種性質為絕對同倫扩充性質,具有這種性質的空間以及用AHE表示.Borsuk曾經介紹這樣一個重要的定理:     

Strongly e-movable convergence and spaces of ANR's

Let X be a metric space and let ANR(X) denote the hyperspace of all compact ANR's in X. This paper introduces a notion of a strongly e-movable convergence for sequences in ANR(X) and proves several characterizations of strongly e-movable convergence. For a (complete) separable metric space X we show that ANR(X) with the topology induced by strongly e-movable convergence can be metrized as a (complete) separable metric space. Moreover, if X is a finite-dimensional compactum, then strongly e-movable convergence induces on ANR(X) the same topology as that induced by Borsuk's homotopy metric.For a separable Q-manifold M, ANR(M) is locally arcwise connected and A, B ? ANR(M) can be joined by an arc in ANR(M) iff there is a simple homotopy equivalence ?: A → B homotopic to the inclusion of A into M.     

Local n-connectivity and approximate lifting

This paper proves that if p:E→Y is an approximate fibration where E is a locally compact separable metric ANR, each point inverse is an FANR, and Y is finite dimensional, then Y is an ANR.     

Linearly ordered Eberlein compact spaces

In this note we prove that every Eberlein compact linearly ordered space is metrizable. (By an Eberlein compact space we mean a topological space which can be embedded as a compact subset of a Banach space with the weak topology.)     

On Efimov spaces and Radon measures

We give a construction under CH of an infinite Hausdorff compact space having no converging sequences and carrying no Radon measure of uncountable type. Under ? we obtain another example of a compact space with no convergent sequences, which in addition has the stronger property that every nonatomic Radon measure on it is uniformly regular. This example refutes a conjecture of Mercourakis from 1996 stating that if every measure on a compact space K is uniformly regular then K is necessarily sequentially compact.     

Separable complete ANR's admitting a group structure are Hilbert manifolds

Let X be a complete-metrizable, separable ANR. The following two facts are shown: (a) if X admits a topological group structure, then either this is a Lie group structure or X is an l₂-manifold; (b) If X is a closed convex set in a complete metric linear space, then X is either locally compact or homeomorphic to l₂.     

Open subspaces of locally compact metric spaces

Although classically every open subspace of a locally compact space is also locally compact, constructively this is not generally true. This paper provides a locally compact remetrization for an open set in a compact metric space and constructs a one-point compactification. MSC: 54D45, 03F60, 03F65.     

Extremally disconnected spaces, subspaces and retracts

A characterization of compact subspaces of extremally disconnected spaces is given which is similar to Gleason's characterization that the extremally disconnected spaces are projective for the class of compact spaces. An equivalence is established between the questions of whether every basically disconnected space is embeddable into an extremally disconnected space and the Borel lifting problems for the category algebras of generalized Cantor cubes. We study an inductive method of strengthening the product topology on the Cantor cubes to extremally disconnected topologies and use this to establish, from CH, that every compact F-space of weight c⁺ embeds into an extremally disconnected space.     

Quotients of Bing spaces

A Bing space is a compact Hausdorff space whose every component is a hereditarily indecomposable continuum. We investigate spaces which are quotients of a Bing space by means of a map which is injective on components. We show that the class of such spaces does not include every compact space, but does properly include the class of compact metric spaces.     

A weak Grothendieck compactness principle

The Grothendieck compactness principle states that every norm compact subset of a Banach space is contained in the closed convex hull of a norm null sequence. In this article, an analogue of the Grothendieck compactness principle is considered when the norm topology of a Banach space is replaced by its weak topology. It is shown that every weakly compact subset of a Banach space is contained in the closed convex hull of a weakly null sequence if and only if the Banach space has the Schur property.