摘要
文[1]、[2]、[3]、[4]分别讨论了S—紧性和可数S—紧性,本文则讨论一种弱于S—紧性和可数S—紧性但对于半T_1空间类来说却等价于可数S—紧性的性质.这种性质称为S—“Bolzano—Weierstrass”性质或S—列紧性质,且要求这种空间的任何无限子集都具有空间内的半聚点.
S-compactness and countable S-compactness were discussed in [1]. [2].[3] [4]. In this paper, we discuss a property that weaker than S-compactness and countable S-compactness but it is equivalant to the countalele S-compactness for Semi-T1 space class. This property is called S-' Bolzano -Weierstrass ' property or S-sequential compactness. And it must be satsfied that there is semi-accumulation point in the space for every infinite subset of this space.
关键词
半连续映射
半T1空间
S-列紧
semi-accurnulation point, semi-derived set, semi-closed set, semi-closure,semi-continuous mapping, semi-T1 space
countable S-compactness, S-sequential compactness.
