You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
61 lines
1.8 KiB
Python
61 lines
1.8 KiB
Python
5 years ago
|
# Natural Language Toolkit: Combinatory Categorial Grammar
|
||
|
|
#
|
||
|
|
# Copyright (C) 2001-2019 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 *
|
||
|
|
|
||
|
|
|
||
|
|
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)
|
||
|
|
|
||
|
|
|
||
|
|
def compute_function_semantics(function, argument):
|
||
|
|
return ApplicationExpression(function, argument).simplify()
|
||
|
|
|
||
|
|
|
||
|
|
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()
|
||
|
|
)
|
||
|
|
|
||
|
|
|
||
|
|
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)
|