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1456 lines
50 KiB
Python
1456 lines
50 KiB
Python
# Natural Language Toolkit: Discourse Representation Theory (DRT)
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#
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# Author: Dan Garrette <dhgarrette@gmail.com>
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#
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# Copyright (C) 2001-2020 NLTK Project
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# URL: <http://nltk.org/>
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# For license information, see LICENSE.TXT
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import operator
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from functools import reduce
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from itertools import chain
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from nltk.sem.logic import (
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APP,
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AbstractVariableExpression,
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AllExpression,
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AndExpression,
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ApplicationExpression,
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BinaryExpression,
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BooleanExpression,
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ConstantExpression,
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EqualityExpression,
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EventVariableExpression,
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ExistsExpression,
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Expression,
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FunctionVariableExpression,
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ImpExpression,
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IndividualVariableExpression,
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LambdaExpression,
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Tokens,
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LogicParser,
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NegatedExpression,
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OrExpression,
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Variable,
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is_eventvar,
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is_funcvar,
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is_indvar,
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unique_variable,
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)
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# Import Tkinter-based modules if they are available
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try:
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from tkinter import Canvas, Tk
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from tkinter.font import Font
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from nltk.util import in_idle
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except ImportError:
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# No need to print a warning here, nltk.draw has already printed one.
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pass
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class DrtTokens(Tokens):
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DRS = "DRS"
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DRS_CONC = "+"
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PRONOUN = "PRO"
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OPEN_BRACKET = "["
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CLOSE_BRACKET = "]"
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COLON = ":"
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PUNCT = [DRS_CONC, OPEN_BRACKET, CLOSE_BRACKET, COLON]
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SYMBOLS = Tokens.SYMBOLS + PUNCT
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TOKENS = Tokens.TOKENS + [DRS] + PUNCT
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class DrtParser(LogicParser):
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"""A lambda calculus expression parser."""
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def __init__(self):
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LogicParser.__init__(self)
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self.operator_precedence = dict(
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[(x, 1) for x in DrtTokens.LAMBDA_LIST]
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+ [(x, 2) for x in DrtTokens.NOT_LIST]
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+ [(APP, 3)]
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+ [(x, 4) for x in DrtTokens.EQ_LIST + Tokens.NEQ_LIST]
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+ [(DrtTokens.COLON, 5)]
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+ [(DrtTokens.DRS_CONC, 6)]
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+ [(x, 7) for x in DrtTokens.OR_LIST]
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+ [(x, 8) for x in DrtTokens.IMP_LIST]
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+ [(None, 9)]
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)
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def get_all_symbols(self):
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"""This method exists to be overridden"""
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return DrtTokens.SYMBOLS
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def isvariable(self, tok):
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return tok not in DrtTokens.TOKENS
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def handle(self, tok, context):
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"""This method is intended to be overridden for logics that
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use different operators or expressions"""
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if tok in DrtTokens.NOT_LIST:
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return self.handle_negation(tok, context)
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elif tok in DrtTokens.LAMBDA_LIST:
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return self.handle_lambda(tok, context)
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elif tok == DrtTokens.OPEN:
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if self.inRange(0) and self.token(0) == DrtTokens.OPEN_BRACKET:
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return self.handle_DRS(tok, context)
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else:
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return self.handle_open(tok, context)
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elif tok.upper() == DrtTokens.DRS:
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self.assertNextToken(DrtTokens.OPEN)
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return self.handle_DRS(tok, context)
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elif self.isvariable(tok):
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if self.inRange(0) and self.token(0) == DrtTokens.COLON:
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return self.handle_prop(tok, context)
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else:
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return self.handle_variable(tok, context)
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def make_NegatedExpression(self, expression):
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return DrtNegatedExpression(expression)
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def handle_DRS(self, tok, context):
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# a DRS
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refs = self.handle_refs()
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if (
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self.inRange(0) and self.token(0) == DrtTokens.COMMA
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): # if there is a comma (it's optional)
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self.token() # swallow the comma
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conds = self.handle_conds(context)
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self.assertNextToken(DrtTokens.CLOSE)
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return DRS(refs, conds, None)
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def handle_refs(self):
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self.assertNextToken(DrtTokens.OPEN_BRACKET)
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refs = []
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while self.inRange(0) and self.token(0) != DrtTokens.CLOSE_BRACKET:
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# Support expressions like: DRS([x y],C) == DRS([x,y],C)
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if refs and self.token(0) == DrtTokens.COMMA:
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self.token() # swallow the comma
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refs.append(self.get_next_token_variable("quantified"))
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self.assertNextToken(DrtTokens.CLOSE_BRACKET)
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return refs
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def handle_conds(self, context):
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self.assertNextToken(DrtTokens.OPEN_BRACKET)
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conds = []
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while self.inRange(0) and self.token(0) != DrtTokens.CLOSE_BRACKET:
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# Support expressions like: DRS([x y],C) == DRS([x, y],C)
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if conds and self.token(0) == DrtTokens.COMMA:
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self.token() # swallow the comma
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conds.append(self.process_next_expression(context))
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self.assertNextToken(DrtTokens.CLOSE_BRACKET)
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return conds
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def handle_prop(self, tok, context):
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variable = self.make_VariableExpression(tok)
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self.assertNextToken(":")
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drs = self.process_next_expression(DrtTokens.COLON)
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return DrtProposition(variable, drs)
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def make_EqualityExpression(self, first, second):
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"""This method serves as a hook for other logic parsers that
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have different equality expression classes"""
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return DrtEqualityExpression(first, second)
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def get_BooleanExpression_factory(self, tok):
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"""This method serves as a hook for other logic parsers that
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have different boolean operators"""
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if tok == DrtTokens.DRS_CONC:
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return lambda first, second: DrtConcatenation(first, second, None)
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elif tok in DrtTokens.OR_LIST:
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return DrtOrExpression
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elif tok in DrtTokens.IMP_LIST:
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def make_imp_expression(first, second):
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if isinstance(first, DRS):
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return DRS(first.refs, first.conds, second)
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if isinstance(first, DrtConcatenation):
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return DrtConcatenation(first.first, first.second, second)
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raise Exception("Antecedent of implication must be a DRS")
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return make_imp_expression
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else:
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return None
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def make_BooleanExpression(self, factory, first, second):
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return factory(first, second)
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def make_ApplicationExpression(self, function, argument):
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return DrtApplicationExpression(function, argument)
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def make_VariableExpression(self, name):
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return DrtVariableExpression(Variable(name))
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def make_LambdaExpression(self, variables, term):
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return DrtLambdaExpression(variables, term)
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class DrtExpression(object):
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"""
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This is the base abstract DRT Expression from which every DRT
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Expression extends.
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"""
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_drt_parser = DrtParser()
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@classmethod
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def fromstring(cls, s):
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return cls._drt_parser.parse(s)
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def applyto(self, other):
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return DrtApplicationExpression(self, other)
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def __neg__(self):
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return DrtNegatedExpression(self)
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def __and__(self, other):
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raise NotImplementedError()
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def __or__(self, other):
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assert isinstance(other, DrtExpression)
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return DrtOrExpression(self, other)
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def __gt__(self, other):
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assert isinstance(other, DrtExpression)
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if isinstance(self, DRS):
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return DRS(self.refs, self.conds, other)
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if isinstance(self, DrtConcatenation):
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return DrtConcatenation(self.first, self.second, other)
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raise Exception("Antecedent of implication must be a DRS")
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def equiv(self, other, prover=None):
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"""
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Check for logical equivalence.
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Pass the expression (self <-> other) to the theorem prover.
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If the prover says it is valid, then the self and other are equal.
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:param other: an ``DrtExpression`` to check equality against
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:param prover: a ``nltk.inference.api.Prover``
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"""
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assert isinstance(other, DrtExpression)
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f1 = self.simplify().fol()
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f2 = other.simplify().fol()
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return f1.equiv(f2, prover)
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@property
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def type(self):
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raise AttributeError(
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"'%s' object has no attribute 'type'" % self.__class__.__name__
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)
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def typecheck(self, signature=None):
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raise NotImplementedError()
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def __add__(self, other):
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return DrtConcatenation(self, other, None)
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def get_refs(self, recursive=False):
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"""
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Return the set of discourse referents in this DRS.
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:param recursive: bool Also find discourse referents in subterms?
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:return: list of ``Variable`` objects
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"""
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raise NotImplementedError()
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def is_pronoun_function(self):
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""" Is self of the form "PRO(x)"? """
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return (
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isinstance(self, DrtApplicationExpression)
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and isinstance(self.function, DrtAbstractVariableExpression)
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and self.function.variable.name == DrtTokens.PRONOUN
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and isinstance(self.argument, DrtIndividualVariableExpression)
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)
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def make_EqualityExpression(self, first, second):
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return DrtEqualityExpression(first, second)
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def make_VariableExpression(self, variable):
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return DrtVariableExpression(variable)
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def resolve_anaphora(self):
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return resolve_anaphora(self)
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def eliminate_equality(self):
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return self.visit_structured(lambda e: e.eliminate_equality(), self.__class__)
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def pretty_format(self):
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"""
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Draw the DRS
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:return: the pretty print string
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"""
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return "\n".join(self._pretty())
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def pretty_print(self):
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print(self.pretty_format())
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def draw(self):
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DrsDrawer(self).draw()
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class DRS(DrtExpression, Expression):
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"""A Discourse Representation Structure."""
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def __init__(self, refs, conds, consequent=None):
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"""
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:param refs: list of ``DrtIndividualVariableExpression`` for the
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discourse referents
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:param conds: list of ``Expression`` for the conditions
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"""
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self.refs = refs
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self.conds = conds
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self.consequent = consequent
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def replace(self, variable, expression, replace_bound=False, alpha_convert=True):
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"""Replace all instances of variable v with expression E in self,
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where v is free in self."""
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if variable in self.refs:
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# if a bound variable is the thing being replaced
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if not replace_bound:
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return self
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else:
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i = self.refs.index(variable)
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if self.consequent:
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consequent = self.consequent.replace(
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variable, expression, True, alpha_convert
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)
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else:
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consequent = None
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return DRS(
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self.refs[:i] + [expression.variable] + self.refs[i + 1 :],
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[
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cond.replace(variable, expression, True, alpha_convert)
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for cond in self.conds
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],
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consequent,
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)
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else:
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if alpha_convert:
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# any bound variable that appears in the expression must
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# be alpha converted to avoid a conflict
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for ref in set(self.refs) & expression.free():
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newvar = unique_variable(ref)
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newvarex = DrtVariableExpression(newvar)
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i = self.refs.index(ref)
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if self.consequent:
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consequent = self.consequent.replace(
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ref, newvarex, True, alpha_convert
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)
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else:
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consequent = None
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self = DRS(
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self.refs[:i] + [newvar] + self.refs[i + 1 :],
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[
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cond.replace(ref, newvarex, True, alpha_convert)
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for cond in self.conds
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],
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consequent,
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)
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# replace in the conditions
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if self.consequent:
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consequent = self.consequent.replace(
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variable, expression, replace_bound, alpha_convert
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)
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else:
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consequent = None
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return DRS(
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self.refs,
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[
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cond.replace(variable, expression, replace_bound, alpha_convert)
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for cond in self.conds
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],
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consequent,
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)
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def free(self):
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""":see: Expression.free()"""
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conds_free = reduce(operator.or_, [c.free() for c in self.conds], set())
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if self.consequent:
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conds_free.update(self.consequent.free())
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return conds_free - set(self.refs)
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def get_refs(self, recursive=False):
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""":see: AbstractExpression.get_refs()"""
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if recursive:
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conds_refs = self.refs + list(
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chain(*(c.get_refs(True) for c in self.conds))
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)
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if self.consequent:
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conds_refs.extend(self.consequent.get_refs(True))
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return conds_refs
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else:
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return self.refs
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def visit(self, function, combinator):
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""":see: Expression.visit()"""
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parts = list(map(function, self.conds))
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if self.consequent:
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parts.append(function(self.consequent))
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return combinator(parts)
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def visit_structured(self, function, combinator):
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""":see: Expression.visit_structured()"""
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consequent = function(self.consequent) if self.consequent else None
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return combinator(self.refs, list(map(function, self.conds)), consequent)
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def eliminate_equality(self):
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drs = self
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i = 0
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while i < len(drs.conds):
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cond = drs.conds[i]
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if (
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isinstance(cond, EqualityExpression)
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and isinstance(cond.first, AbstractVariableExpression)
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and isinstance(cond.second, AbstractVariableExpression)
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):
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drs = DRS(
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list(set(drs.refs) - set([cond.second.variable])),
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drs.conds[:i] + drs.conds[i + 1 :],
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drs.consequent,
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)
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if cond.second.variable != cond.first.variable:
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drs = drs.replace(cond.second.variable, cond.first, False, False)
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i = 0
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i -= 1
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i += 1
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conds = []
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for cond in drs.conds:
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new_cond = cond.eliminate_equality()
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new_cond_simp = new_cond.simplify()
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if (
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not isinstance(new_cond_simp, DRS)
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or new_cond_simp.refs
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or new_cond_simp.conds
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or new_cond_simp.consequent
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):
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conds.append(new_cond)
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consequent = drs.consequent.eliminate_equality() if drs.consequent else None
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return DRS(drs.refs, conds, consequent)
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def fol(self):
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if self.consequent:
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accum = None
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if self.conds:
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accum = reduce(AndExpression, [c.fol() for c in self.conds])
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if accum:
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accum = ImpExpression(accum, self.consequent.fol())
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else:
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accum = self.consequent.fol()
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for ref in self.refs[::-1]:
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accum = AllExpression(ref, accum)
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return accum
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else:
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if not self.conds:
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raise Exception("Cannot convert DRS with no conditions to FOL.")
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accum = reduce(AndExpression, [c.fol() for c in self.conds])
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for ref in map(Variable, self._order_ref_strings(self.refs)[::-1]):
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accum = ExistsExpression(ref, accum)
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return accum
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def _pretty(self):
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refs_line = " ".join(self._order_ref_strings(self.refs))
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cond_lines = [
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cond
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for cond_line in [
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filter(lambda s: s.strip(), cond._pretty()) for cond in self.conds
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]
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for cond in cond_line
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]
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length = max([len(refs_line)] + list(map(len, cond_lines)))
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drs = (
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[
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" _" + "_" * length + "_ ",
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"| " + refs_line.ljust(length) + " |",
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"|-" + "-" * length + "-|",
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]
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+ ["| " + line.ljust(length) + " |" for line in cond_lines]
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+ ["|_" + "_" * length + "_|"]
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)
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if self.consequent:
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return DrtBinaryExpression._assemble_pretty(
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drs, DrtTokens.IMP, self.consequent._pretty()
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)
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return drs
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def _order_ref_strings(self, refs):
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strings = ["%s" % ref for ref in refs]
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ind_vars = []
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func_vars = []
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event_vars = []
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other_vars = []
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for s in strings:
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if is_indvar(s):
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ind_vars.append(s)
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elif is_funcvar(s):
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func_vars.append(s)
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elif is_eventvar(s):
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event_vars.append(s)
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else:
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other_vars.append(s)
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return (
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sorted(other_vars)
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+ sorted(event_vars, key=lambda v: int([v[2:], -1][len(v[2:]) == 0]))
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+ sorted(func_vars, key=lambda v: (v[0], int([v[1:], -1][len(v[1:]) == 0])))
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+ sorted(ind_vars, key=lambda v: (v[0], int([v[1:], -1][len(v[1:]) == 0])))
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)
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def __eq__(self, other):
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r"""Defines equality modulo alphabetic variance.
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If we are comparing \x.M and \y.N, then check equality of M and N[x/y]."""
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if isinstance(other, DRS):
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if len(self.refs) == len(other.refs):
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converted_other = other
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for (r1, r2) in zip(self.refs, converted_other.refs):
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varex = self.make_VariableExpression(r1)
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converted_other = converted_other.replace(r2, varex, True)
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if self.consequent == converted_other.consequent and len(
|
|
self.conds
|
|
) == len(converted_other.conds):
|
|
for c1, c2 in zip(self.conds, converted_other.conds):
|
|
if not (c1 == c2):
|
|
return False
|
|
return True
|
|
return False
|
|
|
|
def __ne__(self, other):
|
|
return not self == other
|
|
|
|
__hash__ = Expression.__hash__
|
|
|
|
def __str__(self):
|
|
drs = "([%s],[%s])" % (
|
|
",".join(self._order_ref_strings(self.refs)),
|
|
", ".join("%s" % cond for cond in self.conds),
|
|
) # map(str, self.conds)))
|
|
if self.consequent:
|
|
return (
|
|
DrtTokens.OPEN
|
|
+ drs
|
|
+ " "
|
|
+ DrtTokens.IMP
|
|
+ " "
|
|
+ "%s" % self.consequent
|
|
+ DrtTokens.CLOSE
|
|
)
|
|
return drs
|
|
|
|
|
|
def DrtVariableExpression(variable):
|
|
"""
|
|
This is a factory method that instantiates and returns a subtype of
|
|
``DrtAbstractVariableExpression`` appropriate for the given variable.
|
|
"""
|
|
if is_indvar(variable.name):
|
|
return DrtIndividualVariableExpression(variable)
|
|
elif is_funcvar(variable.name):
|
|
return DrtFunctionVariableExpression(variable)
|
|
elif is_eventvar(variable.name):
|
|
return DrtEventVariableExpression(variable)
|
|
else:
|
|
return DrtConstantExpression(variable)
|
|
|
|
|
|
class DrtAbstractVariableExpression(DrtExpression, AbstractVariableExpression):
|
|
def fol(self):
|
|
return self
|
|
|
|
def get_refs(self, recursive=False):
|
|
""":see: AbstractExpression.get_refs()"""
|
|
return []
|
|
|
|
def _pretty(self):
|
|
s = "%s" % self
|
|
blank = " " * len(s)
|
|
return [blank, blank, s, blank]
|
|
|
|
def eliminate_equality(self):
|
|
return self
|
|
|
|
|
|
class DrtIndividualVariableExpression(
|
|
DrtAbstractVariableExpression, IndividualVariableExpression
|
|
):
|
|
pass
|
|
|
|
|
|
class DrtFunctionVariableExpression(
|
|
DrtAbstractVariableExpression, FunctionVariableExpression
|
|
):
|
|
pass
|
|
|
|
|
|
class DrtEventVariableExpression(
|
|
DrtIndividualVariableExpression, EventVariableExpression
|
|
):
|
|
pass
|
|
|
|
|
|
class DrtConstantExpression(DrtAbstractVariableExpression, ConstantExpression):
|
|
pass
|
|
|
|
|
|
class DrtProposition(DrtExpression, Expression):
|
|
def __init__(self, variable, drs):
|
|
self.variable = variable
|
|
self.drs = drs
|
|
|
|
def replace(self, variable, expression, replace_bound=False, alpha_convert=True):
|
|
if self.variable == variable:
|
|
assert isinstance(
|
|
expression, DrtAbstractVariableExpression
|
|
), "Can only replace a proposition label with a variable"
|
|
return DrtProposition(
|
|
expression.variable,
|
|
self.drs.replace(variable, expression, replace_bound, alpha_convert),
|
|
)
|
|
else:
|
|
return DrtProposition(
|
|
self.variable,
|
|
self.drs.replace(variable, expression, replace_bound, alpha_convert),
|
|
)
|
|
|
|
def eliminate_equality(self):
|
|
return DrtProposition(self.variable, self.drs.eliminate_equality())
|
|
|
|
def get_refs(self, recursive=False):
|
|
return self.drs.get_refs(True) if recursive else []
|
|
|
|
def __eq__(self, other):
|
|
return (
|
|
self.__class__ == other.__class__
|
|
and self.variable == other.variable
|
|
and self.drs == other.drs
|
|
)
|
|
|
|
def __ne__(self, other):
|
|
return not self == other
|
|
|
|
__hash__ = Expression.__hash__
|
|
|
|
def fol(self):
|
|
return self.drs.fol()
|
|
|
|
def _pretty(self):
|
|
drs_s = self.drs._pretty()
|
|
blank = " " * len("%s" % self.variable)
|
|
return (
|
|
[blank + " " + line for line in drs_s[:1]]
|
|
+ ["%s" % self.variable + ":" + line for line in drs_s[1:2]]
|
|
+ [blank + " " + line for line in drs_s[2:]]
|
|
)
|
|
|
|
def visit(self, function, combinator):
|
|
""":see: Expression.visit()"""
|
|
return combinator([function(self.drs)])
|
|
|
|
def visit_structured(self, function, combinator):
|
|
""":see: Expression.visit_structured()"""
|
|
return combinator(self.variable, function(self.drs))
|
|
|
|
def __str__(self):
|
|
return "prop(%s, %s)" % (self.variable, self.drs)
|
|
|
|
|
|
class DrtNegatedExpression(DrtExpression, NegatedExpression):
|
|
def fol(self):
|
|
return NegatedExpression(self.term.fol())
|
|
|
|
def get_refs(self, recursive=False):
|
|
""":see: AbstractExpression.get_refs()"""
|
|
return self.term.get_refs(recursive)
|
|
|
|
def _pretty(self):
|
|
term_lines = self.term._pretty()
|
|
return (
|
|
[" " + line for line in term_lines[:2]]
|
|
+ ["__ " + line for line in term_lines[2:3]]
|
|
+ [" | " + line for line in term_lines[3:4]]
|
|
+ [" " + line for line in term_lines[4:]]
|
|
)
|
|
|
|
|
|
class DrtLambdaExpression(DrtExpression, LambdaExpression):
|
|
def alpha_convert(self, newvar):
|
|
"""Rename all occurrences of the variable introduced by this variable
|
|
binder in the expression to ``newvar``.
|
|
:param newvar: ``Variable``, for the new variable
|
|
"""
|
|
return self.__class__(
|
|
newvar,
|
|
self.term.replace(self.variable, DrtVariableExpression(newvar), True),
|
|
)
|
|
|
|
def fol(self):
|
|
return LambdaExpression(self.variable, self.term.fol())
|
|
|
|
def _pretty(self):
|
|
variables = [self.variable]
|
|
term = self.term
|
|
while term.__class__ == self.__class__:
|
|
variables.append(term.variable)
|
|
term = term.term
|
|
var_string = " ".join("%s" % v for v in variables) + DrtTokens.DOT
|
|
term_lines = term._pretty()
|
|
blank = " " * len(var_string)
|
|
return (
|
|
[" " + blank + line for line in term_lines[:1]]
|
|
+ [" \ " + blank + line for line in term_lines[1:2]]
|
|
+ [" /\ " + var_string + line for line in term_lines[2:3]]
|
|
+ [" " + blank + line for line in term_lines[3:]]
|
|
)
|
|
|
|
|
|
class DrtBinaryExpression(DrtExpression, BinaryExpression):
|
|
def get_refs(self, recursive=False):
|
|
""":see: AbstractExpression.get_refs()"""
|
|
return (
|
|
self.first.get_refs(True) + self.second.get_refs(True) if recursive else []
|
|
)
|
|
|
|
def _pretty(self):
|
|
return DrtBinaryExpression._assemble_pretty(
|
|
self._pretty_subex(self.first),
|
|
self.getOp(),
|
|
self._pretty_subex(self.second),
|
|
)
|
|
|
|
@staticmethod
|
|
def _assemble_pretty(first_lines, op, second_lines):
|
|
max_lines = max(len(first_lines), len(second_lines))
|
|
first_lines = _pad_vertically(first_lines, max_lines)
|
|
second_lines = _pad_vertically(second_lines, max_lines)
|
|
blank = " " * len(op)
|
|
first_second_lines = list(zip(first_lines, second_lines))
|
|
return (
|
|
[
|
|
" " + first_line + " " + blank + " " + second_line + " "
|
|
for first_line, second_line in first_second_lines[:2]
|
|
]
|
|
+ [
|
|
"(" + first_line + " " + op + " " + second_line + ")"
|
|
for first_line, second_line in first_second_lines[2:3]
|
|
]
|
|
+ [
|
|
" " + first_line + " " + blank + " " + second_line + " "
|
|
for first_line, second_line in first_second_lines[3:]
|
|
]
|
|
)
|
|
|
|
def _pretty_subex(self, subex):
|
|
return subex._pretty()
|
|
|
|
|
|
class DrtBooleanExpression(DrtBinaryExpression, BooleanExpression):
|
|
pass
|
|
|
|
|
|
class DrtOrExpression(DrtBooleanExpression, OrExpression):
|
|
def fol(self):
|
|
return OrExpression(self.first.fol(), self.second.fol())
|
|
|
|
def _pretty_subex(self, subex):
|
|
if isinstance(subex, DrtOrExpression):
|
|
return [line[1:-1] for line in subex._pretty()]
|
|
return DrtBooleanExpression._pretty_subex(self, subex)
|
|
|
|
|
|
class DrtEqualityExpression(DrtBinaryExpression, EqualityExpression):
|
|
def fol(self):
|
|
return EqualityExpression(self.first.fol(), self.second.fol())
|
|
|
|
|
|
class DrtConcatenation(DrtBooleanExpression):
|
|
"""DRS of the form '(DRS + DRS)'"""
|
|
|
|
def __init__(self, first, second, consequent=None):
|
|
DrtBooleanExpression.__init__(self, first, second)
|
|
self.consequent = consequent
|
|
|
|
def replace(self, variable, expression, replace_bound=False, alpha_convert=True):
|
|
"""Replace all instances of variable v with expression E in self,
|
|
where v is free in self."""
|
|
first = self.first
|
|
second = self.second
|
|
consequent = self.consequent
|
|
|
|
# If variable is bound
|
|
if variable in self.get_refs():
|
|
if replace_bound:
|
|
first = first.replace(
|
|
variable, expression, replace_bound, alpha_convert
|
|
)
|
|
second = second.replace(
|
|
variable, expression, replace_bound, alpha_convert
|
|
)
|
|
if consequent:
|
|
consequent = consequent.replace(
|
|
variable, expression, replace_bound, alpha_convert
|
|
)
|
|
else:
|
|
if alpha_convert:
|
|
# alpha convert every ref that is free in 'expression'
|
|
for ref in set(self.get_refs(True)) & expression.free():
|
|
v = DrtVariableExpression(unique_variable(ref))
|
|
first = first.replace(ref, v, True, alpha_convert)
|
|
second = second.replace(ref, v, True, alpha_convert)
|
|
if consequent:
|
|
consequent = consequent.replace(ref, v, True, alpha_convert)
|
|
|
|
first = first.replace(variable, expression, replace_bound, alpha_convert)
|
|
second = second.replace(variable, expression, replace_bound, alpha_convert)
|
|
if consequent:
|
|
consequent = consequent.replace(
|
|
variable, expression, replace_bound, alpha_convert
|
|
)
|
|
|
|
return self.__class__(first, second, consequent)
|
|
|
|
def eliminate_equality(self):
|
|
# TODO: at some point. for now, simplify.
|
|
drs = self.simplify()
|
|
assert not isinstance(drs, DrtConcatenation)
|
|
return drs.eliminate_equality()
|
|
|
|
def simplify(self):
|
|
first = self.first.simplify()
|
|
second = self.second.simplify()
|
|
consequent = self.consequent.simplify() if self.consequent else None
|
|
|
|
if isinstance(first, DRS) and isinstance(second, DRS):
|
|
# For any ref that is in both 'first' and 'second'
|
|
for ref in set(first.get_refs(True)) & set(second.get_refs(True)):
|
|
# alpha convert the ref in 'second' to prevent collision
|
|
newvar = DrtVariableExpression(unique_variable(ref))
|
|
second = second.replace(ref, newvar, True)
|
|
|
|
return DRS(first.refs + second.refs, first.conds + second.conds, consequent)
|
|
else:
|
|
return self.__class__(first, second, consequent)
|
|
|
|
def get_refs(self, recursive=False):
|
|
""":see: AbstractExpression.get_refs()"""
|
|
refs = self.first.get_refs(recursive) + self.second.get_refs(recursive)
|
|
if self.consequent and recursive:
|
|
refs.extend(self.consequent.get_refs(True))
|
|
return refs
|
|
|
|
def getOp(self):
|
|
return DrtTokens.DRS_CONC
|
|
|
|
def __eq__(self, other):
|
|
r"""Defines equality modulo alphabetic variance.
|
|
If we are comparing \x.M and \y.N, then check equality of M and N[x/y]."""
|
|
if isinstance(other, DrtConcatenation):
|
|
self_refs = self.get_refs()
|
|
other_refs = other.get_refs()
|
|
if len(self_refs) == len(other_refs):
|
|
converted_other = other
|
|
for (r1, r2) in zip(self_refs, other_refs):
|
|
varex = self.make_VariableExpression(r1)
|
|
converted_other = converted_other.replace(r2, varex, True)
|
|
return (
|
|
self.first == converted_other.first
|
|
and self.second == converted_other.second
|
|
and self.consequent == converted_other.consequent
|
|
)
|
|
return False
|
|
|
|
def __ne__(self, other):
|
|
return not self == other
|
|
|
|
__hash__ = DrtBooleanExpression.__hash__
|
|
|
|
def fol(self):
|
|
e = AndExpression(self.first.fol(), self.second.fol())
|
|
if self.consequent:
|
|
e = ImpExpression(e, self.consequent.fol())
|
|
return e
|
|
|
|
def _pretty(self):
|
|
drs = DrtBinaryExpression._assemble_pretty(
|
|
self._pretty_subex(self.first),
|
|
self.getOp(),
|
|
self._pretty_subex(self.second),
|
|
)
|
|
if self.consequent:
|
|
drs = DrtBinaryExpression._assemble_pretty(
|
|
drs, DrtTokens.IMP, self._pretty(self.consequent)
|
|
)
|
|
return drs
|
|
|
|
def _pretty_subex(self, subex):
|
|
if isinstance(subex, DrtConcatenation):
|
|
return [line[1:-1] for line in subex._pretty()]
|
|
return DrtBooleanExpression._pretty_subex(self, subex)
|
|
|
|
def visit(self, function, combinator):
|
|
""":see: Expression.visit()"""
|
|
if self.consequent:
|
|
return combinator(
|
|
[function(self.first), function(self.second), function(self.consequent)]
|
|
)
|
|
else:
|
|
return combinator([function(self.first), function(self.second)])
|
|
|
|
def __str__(self):
|
|
first = self._str_subex(self.first)
|
|
second = self._str_subex(self.second)
|
|
drs = Tokens.OPEN + first + " " + self.getOp() + " " + second + Tokens.CLOSE
|
|
if self.consequent:
|
|
return (
|
|
DrtTokens.OPEN
|
|
+ drs
|
|
+ " "
|
|
+ DrtTokens.IMP
|
|
+ " "
|
|
+ "%s" % self.consequent
|
|
+ DrtTokens.CLOSE
|
|
)
|
|
return drs
|
|
|
|
def _str_subex(self, subex):
|
|
s = "%s" % subex
|
|
if isinstance(subex, DrtConcatenation) and subex.consequent is None:
|
|
return s[1:-1]
|
|
return s
|
|
|
|
|
|
class DrtApplicationExpression(DrtExpression, ApplicationExpression):
|
|
def fol(self):
|
|
return ApplicationExpression(self.function.fol(), self.argument.fol())
|
|
|
|
def get_refs(self, recursive=False):
|
|
""":see: AbstractExpression.get_refs()"""
|
|
return (
|
|
self.function.get_refs(True) + self.argument.get_refs(True)
|
|
if recursive
|
|
else []
|
|
)
|
|
|
|
def _pretty(self):
|
|
function, args = self.uncurry()
|
|
function_lines = function._pretty()
|
|
args_lines = [arg._pretty() for arg in args]
|
|
max_lines = max(map(len, [function_lines] + args_lines))
|
|
function_lines = _pad_vertically(function_lines, max_lines)
|
|
args_lines = [_pad_vertically(arg_lines, max_lines) for arg_lines in args_lines]
|
|
func_args_lines = list(zip(function_lines, list(zip(*args_lines))))
|
|
return (
|
|
[
|
|
func_line + " " + " ".join(args_line) + " "
|
|
for func_line, args_line in func_args_lines[:2]
|
|
]
|
|
+ [
|
|
func_line + "(" + ",".join(args_line) + ")"
|
|
for func_line, args_line in func_args_lines[2:3]
|
|
]
|
|
+ [
|
|
func_line + " " + " ".join(args_line) + " "
|
|
for func_line, args_line in func_args_lines[3:]
|
|
]
|
|
)
|
|
|
|
|
|
def _pad_vertically(lines, max_lines):
|
|
pad_line = [" " * len(lines[0])]
|
|
return lines + pad_line * (max_lines - len(lines))
|
|
|
|
|
|
class PossibleAntecedents(list, DrtExpression, Expression):
|
|
def free(self):
|
|
"""Set of free variables."""
|
|
return set(self)
|
|
|
|
def replace(self, variable, expression, replace_bound=False, alpha_convert=True):
|
|
"""Replace all instances of variable v with expression E in self,
|
|
where v is free in self."""
|
|
result = PossibleAntecedents()
|
|
for item in self:
|
|
if item == variable:
|
|
self.append(expression)
|
|
else:
|
|
self.append(item)
|
|
return result
|
|
|
|
def _pretty(self):
|
|
s = "%s" % self
|
|
blank = " " * len(s)
|
|
return [blank, blank, s]
|
|
|
|
def __str__(self):
|
|
return "[" + ",".join("%s" % it for it in self) + "]"
|
|
|
|
|
|
class AnaphoraResolutionException(Exception):
|
|
pass
|
|
|
|
|
|
def resolve_anaphora(expression, trail=[]):
|
|
if isinstance(expression, ApplicationExpression):
|
|
if expression.is_pronoun_function():
|
|
possible_antecedents = PossibleAntecedents()
|
|
for ancestor in trail:
|
|
for ref in ancestor.get_refs():
|
|
refex = expression.make_VariableExpression(ref)
|
|
|
|
# ==========================================================
|
|
# Don't allow resolution to itself or other types
|
|
# ==========================================================
|
|
if refex.__class__ == expression.argument.__class__ and not (
|
|
refex == expression.argument
|
|
):
|
|
possible_antecedents.append(refex)
|
|
|
|
if len(possible_antecedents) == 1:
|
|
resolution = possible_antecedents[0]
|
|
else:
|
|
resolution = possible_antecedents
|
|
return expression.make_EqualityExpression(expression.argument, resolution)
|
|
else:
|
|
r_function = resolve_anaphora(expression.function, trail + [expression])
|
|
r_argument = resolve_anaphora(expression.argument, trail + [expression])
|
|
return expression.__class__(r_function, r_argument)
|
|
|
|
elif isinstance(expression, DRS):
|
|
r_conds = []
|
|
for cond in expression.conds:
|
|
r_cond = resolve_anaphora(cond, trail + [expression])
|
|
|
|
# if the condition is of the form '(x = [])' then raise exception
|
|
if isinstance(r_cond, EqualityExpression):
|
|
if isinstance(r_cond.first, PossibleAntecedents):
|
|
# Reverse the order so that the variable is on the left
|
|
temp = r_cond.first
|
|
r_cond.first = r_cond.second
|
|
r_cond.second = temp
|
|
if isinstance(r_cond.second, PossibleAntecedents):
|
|
if not r_cond.second:
|
|
raise AnaphoraResolutionException(
|
|
"Variable '%s' does not "
|
|
"resolve to anything." % r_cond.first
|
|
)
|
|
|
|
r_conds.append(r_cond)
|
|
if expression.consequent:
|
|
consequent = resolve_anaphora(expression.consequent, trail + [expression])
|
|
else:
|
|
consequent = None
|
|
return expression.__class__(expression.refs, r_conds, consequent)
|
|
|
|
elif isinstance(expression, AbstractVariableExpression):
|
|
return expression
|
|
|
|
elif isinstance(expression, NegatedExpression):
|
|
return expression.__class__(
|
|
resolve_anaphora(expression.term, trail + [expression])
|
|
)
|
|
|
|
elif isinstance(expression, DrtConcatenation):
|
|
if expression.consequent:
|
|
consequent = resolve_anaphora(expression.consequent, trail + [expression])
|
|
else:
|
|
consequent = None
|
|
return expression.__class__(
|
|
resolve_anaphora(expression.first, trail + [expression]),
|
|
resolve_anaphora(expression.second, trail + [expression]),
|
|
consequent,
|
|
)
|
|
|
|
elif isinstance(expression, BinaryExpression):
|
|
return expression.__class__(
|
|
resolve_anaphora(expression.first, trail + [expression]),
|
|
resolve_anaphora(expression.second, trail + [expression]),
|
|
)
|
|
|
|
elif isinstance(expression, LambdaExpression):
|
|
return expression.__class__(
|
|
expression.variable, resolve_anaphora(expression.term, trail + [expression])
|
|
)
|
|
|
|
|
|
class DrsDrawer(object):
|
|
BUFFER = 3 # Space between elements
|
|
TOPSPACE = 10 # Space above whole DRS
|
|
OUTERSPACE = 6 # Space to the left, right, and bottom of the whle DRS
|
|
|
|
def __init__(self, drs, size_canvas=True, canvas=None):
|
|
"""
|
|
:param drs: ``DrtExpression``, The DRS to be drawn
|
|
:param size_canvas: bool, True if the canvas size should be the exact size of the DRS
|
|
:param canvas: ``Canvas`` The canvas on which to draw the DRS. If none is given, create a new canvas.
|
|
"""
|
|
master = None
|
|
if not canvas:
|
|
master = Tk()
|
|
master.title("DRT")
|
|
|
|
font = Font(family="helvetica", size=12)
|
|
|
|
if size_canvas:
|
|
canvas = Canvas(master, width=0, height=0)
|
|
canvas.font = font
|
|
self.canvas = canvas
|
|
(right, bottom) = self._visit(drs, self.OUTERSPACE, self.TOPSPACE)
|
|
|
|
width = max(right + self.OUTERSPACE, 100)
|
|
height = bottom + self.OUTERSPACE
|
|
canvas = Canvas(master, width=width, height=height) # , bg='white')
|
|
else:
|
|
canvas = Canvas(master, width=300, height=300)
|
|
|
|
canvas.pack()
|
|
canvas.font = font
|
|
|
|
self.canvas = canvas
|
|
self.drs = drs
|
|
self.master = master
|
|
|
|
def _get_text_height(self):
|
|
"""Get the height of a line of text"""
|
|
return self.canvas.font.metrics("linespace")
|
|
|
|
def draw(self, x=OUTERSPACE, y=TOPSPACE):
|
|
"""Draw the DRS"""
|
|
self._handle(self.drs, self._draw_command, x, y)
|
|
|
|
if self.master and not in_idle():
|
|
self.master.mainloop()
|
|
else:
|
|
return self._visit(self.drs, x, y)
|
|
|
|
def _visit(self, expression, x, y):
|
|
"""
|
|
Return the bottom-rightmost point without actually drawing the item
|
|
|
|
:param expression: the item to visit
|
|
:param x: the top of the current drawing area
|
|
:param y: the left side of the current drawing area
|
|
:return: the bottom-rightmost point
|
|
"""
|
|
return self._handle(expression, self._visit_command, x, y)
|
|
|
|
def _draw_command(self, item, x, y):
|
|
"""
|
|
Draw the given item at the given location
|
|
|
|
:param item: the item to draw
|
|
:param x: the top of the current drawing area
|
|
:param y: the left side of the current drawing area
|
|
:return: the bottom-rightmost point
|
|
"""
|
|
if isinstance(item, str):
|
|
self.canvas.create_text(x, y, anchor="nw", font=self.canvas.font, text=item)
|
|
elif isinstance(item, tuple):
|
|
# item is the lower-right of a box
|
|
(right, bottom) = item
|
|
self.canvas.create_rectangle(x, y, right, bottom)
|
|
horiz_line_y = (
|
|
y + self._get_text_height() + (self.BUFFER * 2)
|
|
) # the line separating refs from conds
|
|
self.canvas.create_line(x, horiz_line_y, right, horiz_line_y)
|
|
|
|
return self._visit_command(item, x, y)
|
|
|
|
def _visit_command(self, item, x, y):
|
|
"""
|
|
Return the bottom-rightmost point without actually drawing the item
|
|
|
|
:param item: the item to visit
|
|
:param x: the top of the current drawing area
|
|
:param y: the left side of the current drawing area
|
|
:return: the bottom-rightmost point
|
|
"""
|
|
if isinstance(item, str):
|
|
return (x + self.canvas.font.measure(item), y + self._get_text_height())
|
|
elif isinstance(item, tuple):
|
|
return item
|
|
|
|
def _handle(self, expression, command, x=0, y=0):
|
|
"""
|
|
:param expression: the expression to handle
|
|
:param command: the function to apply, either _draw_command or _visit_command
|
|
:param x: the top of the current drawing area
|
|
:param y: the left side of the current drawing area
|
|
:return: the bottom-rightmost point
|
|
"""
|
|
if command == self._visit_command:
|
|
# if we don't need to draw the item, then we can use the cached values
|
|
try:
|
|
# attempt to retrieve cached values
|
|
right = expression._drawing_width + x
|
|
bottom = expression._drawing_height + y
|
|
return (right, bottom)
|
|
except AttributeError:
|
|
# the values have not been cached yet, so compute them
|
|
pass
|
|
|
|
if isinstance(expression, DrtAbstractVariableExpression):
|
|
factory = self._handle_VariableExpression
|
|
elif isinstance(expression, DRS):
|
|
factory = self._handle_DRS
|
|
elif isinstance(expression, DrtNegatedExpression):
|
|
factory = self._handle_NegatedExpression
|
|
elif isinstance(expression, DrtLambdaExpression):
|
|
factory = self._handle_LambdaExpression
|
|
elif isinstance(expression, BinaryExpression):
|
|
factory = self._handle_BinaryExpression
|
|
elif isinstance(expression, DrtApplicationExpression):
|
|
factory = self._handle_ApplicationExpression
|
|
elif isinstance(expression, PossibleAntecedents):
|
|
factory = self._handle_VariableExpression
|
|
elif isinstance(expression, DrtProposition):
|
|
factory = self._handle_DrtProposition
|
|
else:
|
|
raise Exception(expression.__class__.__name__)
|
|
|
|
(right, bottom) = factory(expression, command, x, y)
|
|
|
|
# cache the values
|
|
expression._drawing_width = right - x
|
|
expression._drawing_height = bottom - y
|
|
|
|
return (right, bottom)
|
|
|
|
def _handle_VariableExpression(self, expression, command, x, y):
|
|
return command("%s" % expression, x, y)
|
|
|
|
def _handle_NegatedExpression(self, expression, command, x, y):
|
|
# Find the width of the negation symbol
|
|
right = self._visit_command(DrtTokens.NOT, x, y)[0]
|
|
|
|
# Handle term
|
|
(right, bottom) = self._handle(expression.term, command, right, y)
|
|
|
|
# Handle variables now that we know the y-coordinate
|
|
command(
|
|
DrtTokens.NOT,
|
|
x,
|
|
self._get_centered_top(y, bottom - y, self._get_text_height()),
|
|
)
|
|
|
|
return (right, bottom)
|
|
|
|
def _handle_DRS(self, expression, command, x, y):
|
|
left = x + self.BUFFER # indent the left side
|
|
bottom = y + self.BUFFER # indent the top
|
|
|
|
# Handle Discourse Referents
|
|
if expression.refs:
|
|
refs = " ".join("%s" % r for r in expression.refs)
|
|
else:
|
|
refs = " "
|
|
(max_right, bottom) = command(refs, left, bottom)
|
|
bottom += self.BUFFER * 2
|
|
|
|
# Handle Conditions
|
|
if expression.conds:
|
|
for cond in expression.conds:
|
|
(right, bottom) = self._handle(cond, command, left, bottom)
|
|
max_right = max(max_right, right)
|
|
bottom += self.BUFFER
|
|
else:
|
|
bottom += self._get_text_height() + self.BUFFER
|
|
|
|
# Handle Box
|
|
max_right += self.BUFFER
|
|
return command((max_right, bottom), x, y)
|
|
|
|
def _handle_ApplicationExpression(self, expression, command, x, y):
|
|
function, args = expression.uncurry()
|
|
if not isinstance(function, DrtAbstractVariableExpression):
|
|
# It's not a predicate expression ("P(x,y)"), so leave arguments curried
|
|
function = expression.function
|
|
args = [expression.argument]
|
|
|
|
# Get the max bottom of any element on the line
|
|
function_bottom = self._visit(function, x, y)[1]
|
|
max_bottom = max(
|
|
[function_bottom] + [self._visit(arg, x, y)[1] for arg in args]
|
|
)
|
|
|
|
line_height = max_bottom - y
|
|
|
|
# Handle 'function'
|
|
function_drawing_top = self._get_centered_top(
|
|
y, line_height, function._drawing_height
|
|
)
|
|
right = self._handle(function, command, x, function_drawing_top)[0]
|
|
|
|
# Handle open paren
|
|
centred_string_top = self._get_centered_top(
|
|
y, line_height, self._get_text_height()
|
|
)
|
|
right = command(DrtTokens.OPEN, right, centred_string_top)[0]
|
|
|
|
# Handle each arg
|
|
for (i, arg) in enumerate(args):
|
|
arg_drawing_top = self._get_centered_top(
|
|
y, line_height, arg._drawing_height
|
|
)
|
|
right = self._handle(arg, command, right, arg_drawing_top)[0]
|
|
|
|
if i + 1 < len(args):
|
|
# since it's not the last arg, add a comma
|
|
right = command(DrtTokens.COMMA + " ", right, centred_string_top)[0]
|
|
|
|
# Handle close paren
|
|
right = command(DrtTokens.CLOSE, right, centred_string_top)[0]
|
|
|
|
return (right, max_bottom)
|
|
|
|
def _handle_LambdaExpression(self, expression, command, x, y):
|
|
# Find the width of the lambda symbol and abstracted variables
|
|
variables = DrtTokens.LAMBDA + "%s" % expression.variable + DrtTokens.DOT
|
|
right = self._visit_command(variables, x, y)[0]
|
|
|
|
# Handle term
|
|
(right, bottom) = self._handle(expression.term, command, right, y)
|
|
|
|
# Handle variables now that we know the y-coordinate
|
|
command(
|
|
variables, x, self._get_centered_top(y, bottom - y, self._get_text_height())
|
|
)
|
|
|
|
return (right, bottom)
|
|
|
|
def _handle_BinaryExpression(self, expression, command, x, y):
|
|
# Get the full height of the line, based on the operands
|
|
first_height = self._visit(expression.first, 0, 0)[1]
|
|
second_height = self._visit(expression.second, 0, 0)[1]
|
|
line_height = max(first_height, second_height)
|
|
|
|
# Handle open paren
|
|
centred_string_top = self._get_centered_top(
|
|
y, line_height, self._get_text_height()
|
|
)
|
|
right = command(DrtTokens.OPEN, x, centred_string_top)[0]
|
|
|
|
# Handle the first operand
|
|
first_height = expression.first._drawing_height
|
|
(right, first_bottom) = self._handle(
|
|
expression.first,
|
|
command,
|
|
right,
|
|
self._get_centered_top(y, line_height, first_height),
|
|
)
|
|
|
|
# Handle the operator
|
|
right = command(" %s " % expression.getOp(), right, centred_string_top)[0]
|
|
|
|
# Handle the second operand
|
|
second_height = expression.second._drawing_height
|
|
(right, second_bottom) = self._handle(
|
|
expression.second,
|
|
command,
|
|
right,
|
|
self._get_centered_top(y, line_height, second_height),
|
|
)
|
|
|
|
# Handle close paren
|
|
right = command(DrtTokens.CLOSE, right, centred_string_top)[0]
|
|
|
|
return (right, max(first_bottom, second_bottom))
|
|
|
|
def _handle_DrtProposition(self, expression, command, x, y):
|
|
# Find the width of the negation symbol
|
|
right = command(expression.variable, x, y)[0]
|
|
|
|
# Handle term
|
|
(right, bottom) = self._handle(expression.term, command, right, y)
|
|
|
|
return (right, bottom)
|
|
|
|
def _get_centered_top(self, top, full_height, item_height):
|
|
"""Get the y-coordinate of the point that a figure should start at if
|
|
its height is 'item_height' and it needs to be centered in an area that
|
|
starts at 'top' and is 'full_height' tall."""
|
|
return top + (full_height - item_height) / 2
|
|
|
|
|
|
def demo():
|
|
print("=" * 20 + "TEST PARSE" + "=" * 20)
|
|
dexpr = DrtExpression.fromstring
|
|
print(dexpr(r"([x,y],[sees(x,y)])"))
|
|
print(dexpr(r"([x],[man(x), walks(x)])"))
|
|
print(dexpr(r"\x.\y.([],[sees(x,y)])"))
|
|
print(dexpr(r"\x.([],[walks(x)])(john)"))
|
|
print(dexpr(r"(([x],[walks(x)]) + ([y],[runs(y)]))"))
|
|
print(dexpr(r"(([],[walks(x)]) -> ([],[runs(x)]))"))
|
|
print(dexpr(r"([x],[PRO(x), sees(John,x)])"))
|
|
print(dexpr(r"([x],[man(x), -([],[walks(x)])])"))
|
|
print(dexpr(r"([],[(([x],[man(x)]) -> ([],[walks(x)]))])"))
|
|
|
|
print("=" * 20 + "Test fol()" + "=" * 20)
|
|
print(dexpr(r"([x,y],[sees(x,y)])").fol())
|
|
|
|
print("=" * 20 + "Test alpha conversion and lambda expression equality" + "=" * 20)
|
|
e1 = dexpr(r"\x.([],[P(x)])")
|
|
print(e1)
|
|
e2 = e1.alpha_convert(Variable("z"))
|
|
print(e2)
|
|
print(e1 == e2)
|
|
|
|
print("=" * 20 + "Test resolve_anaphora()" + "=" * 20)
|
|
print(resolve_anaphora(dexpr(r"([x,y,z],[dog(x), cat(y), walks(z), PRO(z)])")))
|
|
print(
|
|
resolve_anaphora(dexpr(r"([],[(([x],[dog(x)]) -> ([y],[walks(y), PRO(y)]))])"))
|
|
)
|
|
print(resolve_anaphora(dexpr(r"(([x,y],[]) + ([],[PRO(x)]))")))
|
|
|
|
print("=" * 20 + "Test pretty_print()" + "=" * 20)
|
|
dexpr(r"([],[])").pretty_print()
|
|
dexpr(
|
|
r"([],[([x],[big(x), dog(x)]) -> ([],[bark(x)]) -([x],[walk(x)])])"
|
|
).pretty_print()
|
|
dexpr(r"([x,y],[x=y]) + ([z],[dog(z), walk(z)])").pretty_print()
|
|
dexpr(r"([],[([x],[]) | ([y],[]) | ([z],[dog(z), walk(z)])])").pretty_print()
|
|
dexpr(r"\P.\Q.(([x],[]) + P(x) + Q(x))(\x.([],[dog(x)]))").pretty_print()
|
|
|
|
|
|
def test_draw():
|
|
try:
|
|
from tkinter import Tk
|
|
except ImportError:
|
|
from nose import SkipTest
|
|
|
|
raise SkipTest("tkinter is required, but it's not available.")
|
|
|
|
expressions = [
|
|
r"x",
|
|
r"([],[])",
|
|
r"([x],[])",
|
|
r"([x],[man(x)])",
|
|
r"([x,y],[sees(x,y)])",
|
|
r"([x],[man(x), walks(x)])",
|
|
r"\x.([],[man(x), walks(x)])",
|
|
r"\x y.([],[sees(x,y)])",
|
|
r"([],[(([],[walks(x)]) + ([],[runs(x)]))])",
|
|
r"([x],[man(x), -([],[walks(x)])])",
|
|
r"([],[(([x],[man(x)]) -> ([],[walks(x)]))])",
|
|
]
|
|
|
|
for e in expressions:
|
|
d = DrtExpression.fromstring(e)
|
|
d.draw()
|
|
|
|
|
|
if __name__ == "__main__":
|
|
demo()
|