用Python实现鲁滨逊归结原理代码
时间: 2024-05-13 10:13:11 浏览: 15
鲁滨逊归结原理是一种基于逻辑的自动定理证明方法,Python可以通过实现一个简单的归结引擎来实现鲁滨逊归结原理。以下是一个简单的Python代码实现:
```python
def unify(x, y, theta):
if theta is None:
return None
elif x == y:
return theta
elif is_variable(x):
return unify_var(x, y, theta)
elif is_variable(y):
return unify_var(y, x, theta)
elif is_compound(x) and is_compound(y):
return unify(x[1:], y[1:], unify(x, y, theta))
else:
return None
def is_variable(x):
return isinstance(x, str) and x.islower()
def is_compound(x):
return isinstance(x, list)
def unify_var(var, x, theta):
if var in theta:
return unify(theta[var], x, theta)
elif occur_check(var, x, theta):
return None
else:
theta[var] = x
return theta
def occur_check(var, x, theta):
if var == x:
return True
elif is_variable(x) and x in theta:
return occur_check(var, theta[x], theta)
elif is_compound(x):
return any([occur_check(var, arg, theta) for arg in x])
else:
return False
def fol_bc_ask(kb, query, theta):
if theta is None:
return None
elif not isinstance(query, list):
for r in kb:
q = [query] + r[1:]
ans = fol_bc_ask(kb, q, unify(query, r, theta))
if ans is not None:
yield ans
else:
first, rest = query, query[1:]
for r in kb:
lhs, rhs = r, r[1:]
phi = unify(first, lhs, theta)
if phi is not None:
new_rhs = [subst(phi, p) for p in rhs]
ans = fol_bc_ask(kb, rest + new_rhs, phi)
if ans is not None:
new_ans = {}
for k,v in phi.items():
if k in query:
new_ans[k] = v
for k,v in ans.items():
if k not in new_ans:
new_ans[k] = v
yield new_ans
def subst(theta, x):
if isinstance(x, list):
return [subst(theta, p) for p in x]
elif x in theta:
return subst(theta, theta[x])
else:
return x
```
该代码实现了基本的一阶逻辑语言,并通过归结规则实现了自动定理证明。其中,`unify`函数实现了变量的一致性检查,`fol_bc_ask`函数实现了向前式推理,`subst`函数实现了代换操作。若需要更深入的了解,请参考相关资料。