人工智能导论实验4子句集消解实验用python语言

以下是Python实现子句集消解的六个步骤：

1. 读取子句集并将其存储在一个列表中。

clauses = []
with open('clauses.txt', 'r') as f:
    for line in f:
        clause = line.strip().split(' v ')
        clauses.append(clause)

2. 找到所有单元子句并将其存储在一个列表中。

unit_clauses = []
for clause in clauses:
    if len(clause) == 1:
        unit_clauses.append(clause[0])

3. 对于每个单元子句，将其与其他子句进行消解。

while unit_clauses:
    unit = unit_clauses.pop()
    new_clauses = []
    for clause in clauses:
        if unit in clause:
            new_clause = [x for x in clause if x != unit]
            if not new_clause:
                print('Empty clause found')
                return False
            new_clauses.append(new_clause)
    clauses = [x for x in clauses if unit not in x]
    clauses += new_clauses
    unit_clauses = []
    for clause in clauses:
        if len(clause) == 1:
            unit_clauses.append(clause[0])

4. 找到所有空子句并返回False。

for clause in clauses:
    if not clause:
        print('Empty clause found')
        return False

5. 如果子句集为空，则返回True。

if not clauses:
    print('Satisfiable')
    return True

6. 如果子句集不为空，则选择一个变量并应用分裂规则。

for clause in clauses:
    for literal in clause:
        if literal[0] != '-':
            new_clause = [x for x in clauses if literal not in x]
            if not new_clause:
                print('Empty clause found')
                return False
            result = dpll(new_clause)
            if result:
                return True
            else:
                new_clause = [x for x in clauses if '-' + literal not in x]
                if not new_clause:
                    print('Empty clause found')
                    return False
                return dpll(new_clause)