关键词: ε句子，ε产生式，ε状态转换函数，带ε动作的有限状态自动机

Abstract: The paper discussed some issues regarding blank string a in the formal language and automata theory. After analysis of the influence of production c on grammar and language classification,the paper discussed the effect of starting symbol S and the starting state qo from the perspective of grammer and infinite state and proposed a simple method to increase language or decrease sentence ε. The paper also proposed a new method to transit ε-NFA to NFA after studying the essence of a state transition function of E-NFA. The method is:first transit ε-NFA to formal grammar and elimmate production ε and single production. After that, regular grammar was obtained. Then transited regular grammar to NFA. Examples were given to support the discussion.

Key words: ε-sentence,ε-producer, ε-state transform function,ε-NFA