人工智能归结原理实验代码python

以下是一个简单的人工智能归结原理实验代码，使用Python编写：

import re

def unify(x, y, theta):
    if theta is None:
        return None
    elif x == y:
        return theta
    elif isinstance(x, str) and x[0].islower():
        return unify_var(x, y, theta)
    elif isinstance(y, str) and y[0].islower():
        return unify_var(y, x, theta)
    elif isinstance(x, list) and isinstance(y, list):
        return unify(x[1:], y[1:], unify(x[0], y[0], theta))
    else:
        return None

def unify_var(var, x, theta):
    if var in theta:
        return unify(theta[var], x, theta)
    elif x in theta:
        return unify(var, theta[x], theta)
    else:
        theta[var] = x
        return theta

def subst(theta, clause):
    if theta is None:
        return None
    elif isinstance(clause, list):
        return [subst(theta, c) for c in clause]
    elif isinstance(clause, str) and clause[0].islower():
        return subst_var(theta, clause)
    else:
        return clause

def subst_var(theta, var):
    if var in theta:
        return subst(theta, theta[var])
    else:
        return var

def resolve(c1, c2):
    for l1 in c1:
        for l2 in c2:
            theta = unify(l1, negate(l2), {})
            if theta is not None:
                resolvent = [subst(theta, c1_l) for c1_l in c1 if c1_l != l1] + \
                            [subst(theta, c2_l) for c2_l in c2 if c2_l != l2]
                yield resolvent

def negate(literal):
    if literal[0] == "~":
        return literal[1:]
    else:
        return "~" + literal

def is_variable(s):
    return isinstance(s, str) and s[0].islower()

def is_constant(s):
    return isinstance(s, str) and s[0].isupper()

def parse_input(s):
    clauses = []
    for line in s.splitlines():
        clause = []
        for literal in re.findall(r'\w+', line):
            if literal[0].isupper():
                literal_type = 'constant'
            else:
                literal_type = 'variable'
            clause.append((literal, literal_type))
        clauses.append(clause)
    return clauses

def main():
    input_str = '''man(x)
                    woman(x)
                    loves(x, y)
                    loves(y, x)'''
    goal = [('loves', 'variable', 'z')]
    clauses = parse_input(input_str)

    for i, clause in enumerate(clauses):
        print(f"Clause {i}: {clause}")

    new = set([tuple(c) for c in clauses])
    while True:
        old = new
        new = set()
        for c1 in old:
            for c2 in old:
                if c1 != c2:
                    for resolvent in resolve(c1, c2):
                        resolvent = tuple(resolvent)
                        if resolvent not in new and resolvent not in old:
                            new.add(resolvent)
                            print(f"New clause: {resolvent}")
                            for goal_literal in goal:
                                if unify(goal_literal, resolvent, {}) is not None:
                                    print("Goal achieved!")
                                    return

if __name__ == '__main__':
    main()

这个代码演示了一些基本的人工智能归结原理操作，包括：

- `unify` 函数：用于统一两个项，即将它们赋予相同的值；
- `subst` 函数：用于将一个子句中的变量替换为它们的统一值；
- `resolve` 函数：用于对两个子句进行归结，生成归结式；
- `negate` 函数：用于将一个文字取反；
- `parse_input` 函数：用于将输入字符串解析为子句列表；
- `main` 函数：用于执行归结过程，直到达到目标。

该代码不包含完整的人工智能归结原理算法实现，但可以作为一个基础框架，让你开始编写自己的代码。