摘要
本文对可数到一伪开映射进行了讨论,得到了如下结果:(1)可数到一伪开映射保持CA_1-空间(CA_2-空间),(2)设T是一拓扑性质,且度量空间具有性质T,如果存在一个不具有性质T的满足(*)的Frechet空间,则可数到一伪开映射不保持性质T.(3)设拓扑性质T满足:(i)关于不相交的拓扑和保持,(ii)在可数到一伪开映射下保持,则性质T满足点可数半开和定理.
In this paper,we discuss countable-to-one pseudo-open mappings and obtain the follow- ing results:(1)Countable-to-one pseudo-open mappings preserve CA_1-Spaces (CA_2- Speces.(2)A proposition on countable-to-one pseudo-open mappings does not preserve topological properties.(3)A point-countable semi-open sum thorem.
关键词
可数
伪开映射
半开和定理
countable
pseudo-open mappings
semi-open sum theorems
