用导集和外部构造拓扑

STRUCTURE TOPOLOGY WITH DERIVED SET OR EXTERIOR SET

在非空集合的子集族中引入导集运算和外部运算，由此出发建立了拓扑空间的概念。

The concept of derived operation and exterior operation are introduced in a nonempty set,from which,a topology on X is structured.Furthermore,the equivalence between the image of a subset under derived operation or exterior operation,and the derived set or exteriorset.of the same subset is discussed.