Source code for nltk.ccg.logic

# Natural Language Toolkit: Combinatory Categorial Grammar
#
# Copyright (C) 2001-2018 NLTK Project
# Author: Tanin Na Nakorn (@tanin)
# URL: <http://nltk.org/>
# For license information, see LICENSE.TXT
"""
Helper functions for CCG semantics computation
"""

from nltk.sem.logic import *

[docs]def compute_type_raised_semantics(semantics): core = semantics parent = None while isinstance(core, LambdaExpression): parent = core core = core.term var = Variable("F") while var in core.free(): var = unique_variable(pattern=var) core = ApplicationExpression(FunctionVariableExpression(var), core) if parent is not None: parent.term = core else: semantics = core return LambdaExpression(var, semantics)
[docs]def compute_function_semantics(function, argument): return ApplicationExpression(function, argument).simplify()
[docs]def compute_composition_semantics(function, argument): assert isinstance(argument, LambdaExpression), "`" + str(argument) + "` must be a lambda expression" return LambdaExpression(argument.variable, ApplicationExpression(function, argument.term).simplify())
[docs]def compute_substitution_semantics(function, argument): assert isinstance(function, LambdaExpression) and isinstance(function.term, LambdaExpression), "`" + str(function) + "` must be a lambda expression with 2 arguments" assert isinstance(argument, LambdaExpression), "`" + str(argument) + "` must be a lambda expression" new_argument = ApplicationExpression(argument, VariableExpression(function.variable)).simplify() new_term = ApplicationExpression(function.term, new_argument).simplify() return LambdaExpression(function.variable, new_term)