nltk.inference.DiscourseTester

class nltk.inference.DiscourseTester

Bases: object

Check properties of an ongoing discourse.

__init__(input, reading_command=None, background=None)

Initialize a DiscourseTester.

Parameters

• input (list of str) – the discourse sentences

• background (list(Expression)) – Formulas which express background assumptions

sentences()

Display the list of sentences in the current discourse.

add_sentence(sentence, informchk=False, consistchk=False)

Add a sentence to the current discourse.

Updates self._input and self._sentences. :param sentence: An input sentence :type sentence: str :param informchk: if True, check that the result of adding the sentence is thread-informative. Updates self._readings. :param consistchk: if True, check that the result of adding the sentence is thread-consistent. Updates self._readings.

retract_sentence(sentence, verbose=True)

Remove a sentence from the current discourse.

Updates self._input, self._sentences and self._readings. :param sentence: An input sentence :type sentence: str :param verbose: If True, report on the updated list of sentences.

grammar()

Print out the grammar in use for parsing input sentences

readings(sentence=None, threaded=False, verbose=True, filter=False, show_thread_readings=False)

Construct and show the readings of the discourse (or of a single sentence).

Parameters

• sentence (str) – test just this sentence

• threaded – if True, print out each thread ID and the corresponding thread.

• filter – if True, only print out consistent thread IDs and threads.

expand_threads(thread_id, threads=None)

Given a thread ID, find the list of logic.Expression objects corresponding to the reading IDs in that thread.

Parameters

• thread_id (str) – thread ID

• threads (dict) – a mapping from thread IDs to lists of reading IDs

Returns

A list of pairs (rid, reading) where reading is the logic.Expression associated with a reading ID

Return type

list of tuple

models(thread_id=None, show=True, verbose=False)

Call Mace4 to build a model for each current discourse thread.

Parameters

• thread_id (str) – thread ID

• show – If True, display the model that has been found.

add_background(background, verbose=False)

Add a list of background assumptions for reasoning about the discourse.

When called, this method also updates the discourse model’s set of readings and threads. :param background: Formulas which contain background information :type background: list(Expression)

background()

Show the current background assumptions.

static multiply(discourse, readings)

Multiply every thread in discourse by every reading in readings.

Given discourse = [[‘A’], [‘B’]], readings = [‘a’, ‘b’, ‘c’] , returns [[‘A’, ‘a’], [‘A’, ‘b’], [‘A’, ‘c’], [‘B’, ‘a’], [‘B’, ‘b’], [‘B’, ‘c’]]

Parameters

• discourse (list of lists) – the current list of readings

• readings (list(Expression)) – an additional list of readings

Return type

A list of lists