LF拓扑空间中的序列连通性

主要引进了拓扑空间中序列连通的定义,并给出了序列连通的一些刻画和性质研究.     

关于rectifiable空间中的局部(序列)连通性的几个注记

给出连通的rectifiable空间是局部序列连通(或局部连通)的刻画,推广了拓扑群中的相应结果;利用rectifiable空间G中e的局部邻域基给出G是局部连通(或局部序列连通)的刻画;证明了若A是rectifiable空间G中的序列开子集,那么H=A是G的序列开rectifiable子空间.     

δ-连通空间

利用δ-分离集,将连通空间进行了扩充,定义了一类更广泛的拓扑空间δ-连通空间,并对其性质作了讨论,得到了一些类似于连通空间的性质.同时对δ-连通分支及局部δ-连通性也作了研究,得到了一些较好的结果.     

超空间的连通性和c半层空间性质

设X是Hausdorff拓扑空间,超空间S(X)中的每一元素是X中有限个收敛序列的并且赋予Vietoris拓扑.主要讨论当空间X分别是序列连通、道路连通和c半层空间,则超空间S(X)是否分别是序列连通、道路连通和c半层空间.对这些问题给出(部分)回答.     

连通度量空间的映象

拓扑空间X称为s连通,若X不能表示为两个非空的不相交的序列开集之并.本文纠正了A.Fedeli和A.Le Donne关于连通度量空间映象的错误论证,证明了s连通性可刻画为连通度量空间的连续的序列覆盖映象,从而导出连通的序列空间(或Frechet空间)可刻画为连通度量空间的商映象(或伪开映象),回答了V.V.Tkachuk在Proc.Amer.Math.Soc.上提出的问题.     

连通度量空间的映象

拓扑空间X称为s连通,若X不能表示为两个非空的不相交的序列开集之并.本文纠正了A.Fedeli 和A.Le Donne关于连通度量空间映象的错误论证,证明了s连通性可刻画为连通度量空间的连续的序列覆盖映象,从而导出连通的序列空间(或FrEchet空间)可刻画为连通度量空间的商映象(或伪开映象),回答了V.V.Tkachuk在Proc.Amer.Math Soc.上提出的问题.     

Lω-空间的ωθ-连通性

研究了Lω-空间的ωθ-连通性问题。利用Lω-空间的的ωθ-闭集和ωθ-连通集等概念，系统讨论了这些概念的特征性质，证明了Lω-空间的ωθ-连通性具有同胚不变性等性质。     

LF保序算子空间的ω-连通性

本文研究了LF保序算子空间的ω-连通性问题.利用LF保序算子空间的ω-远域和ω-连通集等概念,讨论了这些概念的特征性质.同时,给出了拓扑生成的F保序算子空间的若干ω-连通性质.     

局部θ-连通空间的几个性质

θ-连通空间是比连通空间更广泛的一类空间,在前人的研究基础之上得到了局部口一连通空间的充分必要条件,证明了局部θ-连通空间在商映射下是不变的,同时也得到了和空间 α∈AXα与乘积空间Пs∈SX8是局部θ-连通空间的充分必要条件．     

L-预拓扑空间的强连通集和局部强连通L-预拓扑空间

定义L-预拓扑空间中的强连通L-子集以及L-预拓扑空间的局部强连通性,证明了它们和拓扑空间中的连通子集以及局部连通性拓扑空间有类似的性质,证明了局部强连通L-预拓扑空间和连续映射构成的范畴L-LSCPS是topological construct.     

对偶导集及其应用

借助对偶范畴的思想和方法在点集拓扑学中引入了对偶导集概念,讨论了对偶导集和对偶导集运算的相关性质.并以此为基础引入了对偶连通空间的概念,讨论了对偶连通空间和连通空间之间的关系,借此给出了不连通空间的几个等价刻画.为拓扑空间的研究提供了新的途径.     

Sequential completeness of subspaces of products of two cardinals

Let be a cardinal number with the usual order topology. We prove that all subspaces of ² are weakly sequentially complete and, as a corollary, all subspaces of are sequentially complete. Moreover we show that a subspace of (₁ + 1)² need not be sequentially complete, but note that X = A × B is sequentially complete whenever A and B are subspaces of .     

On the resolvability of locally connected spaces

We solve a problem of Padmavally about resolvability of locally connected spaces, in the case where the space under consideration is regular.

     

灰拓扑空间的连通性

研究灰拓扑空间的连通性,给出了灰拓扑空间连通定义和有关定理,并且研究了灰连通分支。     

Some Characterizations of Spaces with Weak Form of $cs$-Networks

In this paper, we introduce the concept of statistically sequentially quotient map:A mapping f : X → Y is statistically sequentially quotient map if whenever a convergent sequence S in Y, there is a convergent sequence L in X such that f(L) is statistically dense in S. Also, we discuss the relation between statistically sequentially quotient map and covering maps by characterizing statistically sequentially quotient map and we prove that every closed and statistically sequentially quotient image of a g-metrizable space is g-metrizable. Moreover,we discuss about the preservation of generalization of metric space in terms of weakbases and sn-networks by closed and statistically sequentially quotient map.     

A Note on Locally Pathwise Connected Metric Spaces

Given any metric space, we construct its uniformly locally pathwise connected coreflection in the category of all metric spaces and uniformly continuous maps.      

On countable connected locally connected almost regular Urysohn spaces

We construct connected, locally connected, almost regular, countable, Urysohn spaces. This answers a problem of G.X. Ritter. We show that there are 2^c such non-homeomorphic spaces. We also show that there are 2^c non-homeomorphic spaces which are further rigid. We discuss the group of homeomorphisms of such spaces.The following question was raised by G.X. Ritter: Does there exist a countable connected locally connected Urysohn space which is almost regular? We answer this question in the affirmative and in fact, show that not only are there as many as 2^c such spaces but that there are just as many rigid spaces with the same properties. Furthermore we show that every countable Urysohn space is a subspace of such a space. We also prove that every countable group is isomorphic to the group of autohomeomorphisms of some connected locally connected almost regular Urysohn space. Examples are given of groups of order c which can be represented in this manner.     

On compactifications with path connected remainders

We prove that every separable and metrizable space admits a metrizable compactification with a remainder that is both path connected and locally path connected. This result answers a question of P. Simon.