#?
#?Propositional?and?First-Order?logic.
#
#?Compiled?against?Python?2.7


import?re

“““
define?some?basic?functions?used?below
“““

def?isnumber（x）:
????return?hasattr（x?‘__int__‘）

def?num_or_str（x）:
????if?isnumber（x）:?return?x
????try:
????????return?int（x）
????except?ValueError:
????????try:
????????????return?float（x）
????????except?ValueError:
????????????return?str（x）.strip（）

def?find_if（predicate?seq）:
????for?x?in?seq:
????????if?predicate（x）:?return?x
????return?None

#______________________________________________________________________________

class?KB:
????def?__init__（self?sentence=None）:
????????abstract

????def?tell（self?sentence）:
????????“Add?the?sentence?to?the?KB.“
????????abstract

????def?ask（self?query）:
????????for?result?in?self.ask_generator（query）:
????????????return?result
????????return?False

????def?ask_generator（self?query）:
????????“Yield?all?the?substitutions?that?make?query?true.“
????????abstract

????def?retract（self?sentence）:
????????“Remove?sentence?from?the?KB.“
????????abstract


class?PropKB（KB）:
????“A?KB?for?propositional?logic.?Inefficient?with?no?indexing.“

????def?__init__（self?sentence=None）:
????????self.conds?=?[]
????????if?sentence:
????????????self.tell（sentence）

????def?tell（self?sentence）:
????????“Add?the?sentence‘s?conds?to?the?KB.“
????????self.conds.extend（conjuncts（to_cnf（sentence）））

????def?ask_generator（self?query）:
????????“Yield?the?empty?substitution?if?KB?implies?query;?else?nothing.“
????????if?tt_entails（Expr（‘&‘?*self.conds）?query）:
????????????yield?{}

????def?retract（self?sentence）:
????????“Remove?the?sentence‘s?conds?from?the?KB.“
????????for?c?in?conjuncts（to_cnf（sentence））:
????????????if?c?in?self.conds:
????????????????self.conds.remove（c）

#______________________________________________________________________________

class?Expr:
????def?__init__（self?op?*args）:
????????“Op?is?a?string?or?number;?args?are?Exprs?（or?are?coerced?to?Exprs）.“
????????assert?isinstance（op?str）?or?（isnumber（op）?and?not?args）
????????self.op?=?num_or_str（op）
????????self.args?=?map（expr?args）

????def?__call__（self?*args）:
????????assert?is_symbol（self.op）?and?not?self.args
????????return?Expr（self.op?*args）

????def?__repr__（self）:
????????“Show?something?like?‘P‘?or?‘P（x?y）‘?or?‘~P‘?or?‘（P?|?Q?|?R）‘“
????????if?not?self.args:?????????
????????????return?str（self.op）
????????elif?is_symbol（self.op）:??
????????????return?‘%s（%s）‘?%?（self.op?‘?‘.join（map（repr?self.args）））
????????elif?len（self.args）?==?1:?
????????????return?self.op?+?repr（self.args[0]）
????????else:?????????????????????
????????????return?‘（%s）‘?%?（‘?‘+self.op+‘?‘）.join（map（repr?self.args））

????def?__eq__（self?other）:
????????return?（other?is?self）?or?（isinstance（other?Expr）
????????????and?self.op?==?other.op?and?self.args?==?other.args）

????def?__ne__（self?other）:
????????return?not?self.__eq__（other）

????def?__hash__（self）:
????????“Need?a?hash?method?so?Exprs?can?live?in?dicts.“

?屬性????????????大小?????日期????時(shí)間???名稱
-----------?---------??----------?-----??----
?????文件????????8970??2018-12-10?10:43??WumpusWorldAI.py
?????文件???????10037??2018-12-10?10:39??logic.py
?????文件????????2909??2018-12-10?10:39??logic_info_KB.py
?????文件?????????822??2018-12-10?10:32??README.md