first countable topological space 中文意思是什麼
first countable topological space
解釋
第一可數拓撲空間- first : adj 1 最初的，最早的。2 最上等的，第一流的。3 基本的，概要的。4 高音（調）的。n 1 最初，第一；第...
- countable : 可計算的
- topological : 拓撲的
- space : n 1 空間；太空。2 空隙，空地；場地；（火車輪船飛機中的）座位；餘地；篇幅。3 空白；間隔；距離。4 ...
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It is a main task of general topology to compare different spaces. mappings which connect different spaces are important tools to complete it. which mapping preserves some special generalized metric space is a basic probleme in investigating generalized metric spaces by mappings. g - first countable spaces and g - metri / able spaces have many important topological properities so to investigate which mapping preserves them is very necessary. in [ 7 ], clnian liu and mu - ming dai prove that open - closed mappings preserve g - metri / able spaces ; whether open mappings preserve g - first countable spaces is an open probleme asked by tanaka in [ 6 ]. in [ 4 ], sheng - xiang xia introduces weak opewn mappings and investigates the relations between them and 1 - sequence - covering mappings. in the second section of this article, we investigate weak open mappings have the relations with other mappings and prove that the finite - to - one weak open mappings preserve g - first countable, spaces and weak open closed mapping preserve g - metrizable spaces. in the third section, we investigate an example to show that perfect mappings do not preserve g - first countable spaces, g - metrizable spaces, sn - first countable spaces and sn - metrizable spaces
在文獻[ 4 ]中，夏省祥引進了弱開映射，並研究了它和1 -序列覆蓋映射的關系。本文在第二節研究了弱開映射與序列商映射，幾乎開映射的關系，證明了有限到一的弱開映射保持g -第一可數空間；弱開閉映射保持g -度量空間。第三節研究了文獻[ 5 ]中的一個例子，證明了完備映射不保持g -第一可數空間， g -度量空間， sn -第一可數空間， sn -度量空間。
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