The classification of differential function germs whose codimention is less than or equal to 5 had been done by topologist r . thom 对于余维小于等于5的可微函数芽的分类，拓扑学家r thom早就已经给出了分类结果。
2.
In order to prove the arbitrary cardinal number alexandroff - urysohn addition theorem put forward in 1923 , the famous former soviet union topologist a . arhangel ' skii introduced network which is the important extension of base in 1959 1959年前苏联著名拓扑学家a arhangel ' skii为了证明1923年提出的任意基数的alexandroff - urysohn加法定理，引进了基概念的重要推广? ?网络( network ) 。
