代码实现nfa弧的三种化简
时间: 2024-03-23 14:39:24 浏览: 38
NFA的弧可以通过三种方式进行化简,分别是ε-closure,ε-move和ε-elimination。下面是它们的代码实现:
1. ε-closure:对于一个状态集合S,ε-closure返回所有通过ε弧可以到达的状态集合。
```python
def epsilon_closure(states, transitions):
closure = set(states)
stack = list(states)
while stack:
state = stack.pop()
if state in transitions and 'ε' in transitions[state]:
for state2 in transitions[state]['ε']:
if state2 not in closure:
closure.add(state2)
stack.append(state2)
return closure
```
2. ε-move:对于一个状态集合S和一个字符c,ε-move返回通过c和ε弧可以到达的状态集合。
```python
def epsilon_move(states, transitions, c):
move = set()
for state in states:
if state in transitions and c in transitions[state]:
move |= set(transitions[state][c])
return epsilon_closure(move, transitions)
```
3. ε-elimination:对于一个状态集合S,ε-elimination会将S中的ε弧全部转换为普通弧,并返回新的状态集合。
```python
def epsilon_elimination(states, transitions):
new_states = set(states)
for state in states:
if state in transitions and 'ε' in transitions[state]:
for state2 in transitions[state]['ε']:
new_states.add(state2)
for c in transitions[state]:
if c != 'ε':
if c not in transitions[state2]:
transitions[state2][c] = []
transitions[state2][c] += transitions[state][c]
return new_states
```
以上代码中,transitions是一个字典,表示状态之间的转移关系。例如,transitions[state][c]表示从状态state出发,通过字符c可以到达的状态集合。