axioms of countability

In this paper,we discuss when f(x) is a real valued function on E(ER 1),the sets of various discontinuous points of f(x) is or not is countable;when f(x) is semi continuous function,discontinuous points of f(x) is or not is countable.

给出当 f(x)是 E(E R1)上的实值有界半连续函数时 ,f(x)的不连续点是至多可数的 ,从而当 f(x)为强半连续函数时 ,则 f(x)取至多可数值。

English nouns can be practically classified into countable nouns and uncountable nouns.

英语名词可以从实用的角度分为可数名词及不可数名词。

In this paper, the concepts of twelve countable compactness in symmetric topological molecular lattices are introduced.

在对称拓扑分子格中引入12种可数紧性的概念,着重指出了它们在极不连通的对称拓扑分子格中的内在联系。