def resolution(self, predicates, target):
'''从已知谓词关系公式证明给定谓词公式
如果能够证明给定谓词公式，返回真，否则返回假
:param predicates: 已知谓词公式
:type predicates: list of string
:param target: 待证明谓词公式
:type target: string
'''
# 将所有谓词关系公式转换成内部表现形式
conditions = [expr(i) for i in predicates]
target = expr(target)
# 使用反演法，将待证明结论取反
negated_target = target.negate()
# 构造条件谓词集合
predicates = conditions + [negated_target]
# 将谓词集合进行 skolem 标准化，转换为子句集
clauses_set = [skolemize(i) for i in predicates]
# 进行归结
solver = ResolutionProverCommand(None, clauses_set)
# 检查迭代后的子句集是否为空
result = solver.prove()
# 生成证明过程
self._proof = solver.proof()
return result
def resolution(self, predicates, target):
'''从已知谓词关系公式证明给定谓词公式
如果能够证明给定谓词公式，返回真，否则返回假
:param predicates: 已知谓词公式
:type predicates: list of string
:param target: 待证明谓词公式
:type target: string
'''
# 将所有谓词关系公式转换成内部表现形式
conditions = [expr(i) for i in predicates]
target = expr(target)
# 使用反演法，将待证明结论取反
negated_target = target.negate()
# 构造条件谓词集合
predicates = conditions + [negated_target]
# 将谓词集合进行 skolem 标准化，转换为子句集
clauses_set = [skolemize(i) for i in predicates]
# 进行归结
solver = ResolutionProverCommand(None, clauses_set)
# 检查迭代后的子句集是否为空
result = solver.prove()
# 生成证明过程
self._proof = solver.proof()
return result
def clausify(expression):
"""
Skolemize, clausify, and standardize the variables apart.
"""
clause_list = []
for clause in _clausify(skolemize(expression)):
for free in clause.free():
if is_indvar(free.name):
newvar = VariableExpression(unique_variable())
clause = clause.replace(free, newvar)
clause_list.append(clause)
return clause_list
def clausify(expression):
"""
Skolemize, clausify, and standardize the variables apart.
"""
clause_list = []
for clause in _clausify(skolemize(expression)):
for free in clause.free():
if is_indvar(free.name):
newvar = VariableExpression(unique_variable())
clause = clause.replace(free, newvar)
clause_list.append(clause)
return clause_list