一个集合右上角加星号是什么意思?表示的是这个集合的什么呢?
问题描述：
一个集合右上角加星号是什么意思?表示的是这个集合的什么呢?
比如一个字符集T={a,b,c,f,d,s,t,r,e,w...},得到的是什么？*在T的右上角
答
那个星号是克莱尼星号
应用在正则表达式
Kleene 星号应用於字符串集合的例子：
{"ab","c"}* = {ε,"ab","c","abab","abc","cab","cc","ababab","ababc","abcab","abcc","cabab","cabc","ccab","ccc",...}
Kleene 星号应用於字元集合的例子：
{'a','b','c'}* = {ε,"a","b","c","aa","ab","ac","ba","bb","bc",...}