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.
69 lines
2.4 KiB
Plaintext
69 lines
2.4 KiB
Plaintext
.. Copyright (C) 2001-2019 NLTK Project
|
|
.. For license information, see LICENSE.TXT
|
|
|
|
.. see also: gluesemantics.doctest
|
|
|
|
==============================================================================
|
|
Glue Semantics
|
|
==============================================================================
|
|
|
|
>>> from nltk.sem.glue import *
|
|
>>> nltk.sem.logic._counter._value = 0
|
|
|
|
--------------------------------
|
|
Initialize the Dependency Parser
|
|
--------------------------------
|
|
>>> from nltk.parse.malt import MaltParser
|
|
|
|
>>> tagger = RegexpTagger(
|
|
... [('^(John|Mary)$', 'NNP'),
|
|
... ('^(sees|chases)$', 'VB'),
|
|
... ('^(a)$', 'ex_quant'),
|
|
... ('^(every)$', 'univ_quant'),
|
|
... ('^(girl|dog)$', 'NN')
|
|
... ])
|
|
>>> depparser = MaltParser(tagger=tagger)
|
|
|
|
--------------------
|
|
Automated Derivation
|
|
--------------------
|
|
>>> glue = Glue(depparser=depparser)
|
|
>>> readings = glue.parse_to_meaning('every girl chases a dog'.split())
|
|
>>> for reading in sorted([r.simplify().normalize() for r in readings], key=str):
|
|
... print(reading.normalize())
|
|
all z1.(girl(z1) -> exists z2.(dog(z2) & chases(z1,z2)))
|
|
exists z1.(dog(z1) & all z2.(girl(z2) -> chases(z2,z1)))
|
|
|
|
>>> drtglue = DrtGlue(depparser=depparser)
|
|
>>> readings = drtglue.parse_to_meaning('every girl chases a dog'.split())
|
|
>>> for reading in sorted([r.simplify().normalize() for r in readings], key=str):
|
|
... print(reading)
|
|
([],[(([z1],[girl(z1)]) -> ([z2],[dog(z2), chases(z1,z2)]))])
|
|
([z1],[dog(z1), (([z2],[girl(z2)]) -> ([],[chases(z2,z1)]))])
|
|
|
|
--------------
|
|
With inference
|
|
--------------
|
|
|
|
Checking for equality of two DRSs is very useful when generating readings of a sentence.
|
|
For example, the ``glue`` module generates two readings for the sentence
|
|
*John sees Mary*:
|
|
|
|
>>> from nltk.sem.glue import DrtGlue
|
|
>>> readings = drtglue.parse_to_meaning('John sees Mary'.split())
|
|
>>> for drs in sorted([r.simplify().normalize() for r in readings], key=str):
|
|
... print(drs)
|
|
([z1,z2],[John(z1), Mary(z2), sees(z1,z2)])
|
|
([z1,z2],[Mary(z1), John(z2), sees(z2,z1)])
|
|
|
|
However, it is easy to tell that these two readings are logically the
|
|
same, and therefore one of them is superfluous. We can use the theorem prover
|
|
to determine this equivalence, and then delete one of them. A particular
|
|
theorem prover may be specified, or the argument may be left off to use the
|
|
default.
|
|
|
|
>>> readings[0].equiv(readings[1])
|
|
True
|
|
|
|
|