鲁宾孙归结原理 python

鲁宾孙归结原理是一种自动推理方法，用于判断一个命题逻辑公式是否可满足。它基于鲁宾孙归结规则，通过应用归结规则来简化公式，直到得到一个空子句表示不可满足性，或者无法再应用归结规则为止。

下面是一个简单的 Python 实现示例：

def resolve(clause1, clause2):
    resolvents = set()
    for literal1 in clause1:
        for literal2 in clause2:
            if literal1 == -literal2:
                resolvent = (clause1 - {literal1}) | (clause2 - {literal2})
                if not resolvent:
                    resolvents.add(frozenset())
                else:
                    resolvents.add(resolvent)
    return resolvents

def resolution(clauses):
    new = set(clauses)
    while True:
        pairs = [(clause1, clause2) for clause1 in new for clause2 in new if clause1 != clause2]
        new_resolvents = set()
        for (clause1, clause2) in pairs:
            resolvents = resolve(clause1, clause2)
            if frozenset() in resolvents:
                return True
            new_resolvents |= resolvents
        if not new_resolvents.issubset(new):
            new |= new_resolvents
        else:
            return False

# 示例用法
clauses = [{-1, 2}, {-2, 3}, {-3, 1}]
is_satisfiable = not resolution(clauses)
print("可满足性：", is_satisfiable)