有限状态机 A finite automaton M is a5-tuple(2,qo,A,∑，8)， where O is a finite set of states, ·qo∈O is the start state, A CO is a distinguished set of accepting states, ·∑is a finite input alphabet, ·8 is a function from O×∑into O,called the transition function of M. a input 《语句=（前缀）a state a b (前缀)：= 0 10 (前缀)：=（前缀）b|(前缀)aa 00有限状态机 语句::=前缀 a 前缀::= 前缀::=前缀b | 前缀aa