jupytersketcher/Lib/site-packages/nltk/sem/__init__.py

# Natural Language Toolkit: Semantic Interpretation
#
# Copyright (C) 2001-2020 NLTK Project
# Author: Ewan Klein <ewan@inf.ed.ac.uk>
# URL: <http://nltk.org/>
# For license information, see LICENSE.TXT

"""
NLTK Semantic Interpretation Package

This package contains classes for representing semantic structure in
formulas of first-order logic and for evaluating such formulas in
set-theoretic models.

    >>> from nltk.sem import logic
    >>> logic._counter._value = 0

The package has two main components:

 - ``logic`` provides support for analyzing expressions of First
   Order Logic (FOL).
 - ``evaluate`` allows users to recursively determine truth in a
   model for formulas of FOL.

A model consists of a domain of discourse and a valuation function,
which assigns values to non-logical constants. We assume that entities
in the domain are represented as strings such as ``'b1'``, ``'g1'``,
etc. A ``Valuation`` is initialized with a list of (symbol, value)
pairs, where values are entities, sets of entities or sets of tuples
of entities.
The domain of discourse can be inferred from the valuation, and model
is then created with domain and valuation as parameters.

    >>> from nltk.sem import Valuation, Model
    >>> v = [('adam', 'b1'), ('betty', 'g1'), ('fido', 'd1'),
    ... ('girl', set(['g1', 'g2'])), ('boy', set(['b1', 'b2'])),
    ... ('dog', set(['d1'])),
    ... ('love', set([('b1', 'g1'), ('b2', 'g2'), ('g1', 'b1'), ('g2', 'b1')]))]
    >>> val = Valuation(v)
    >>> dom = val.domain
    >>> m = Model(dom, val)
"""

from nltk.sem.util import parse_sents, interpret_sents, evaluate_sents, root_semrep
from nltk.sem.evaluate import (
    Valuation,
    Assignment,
    Model,
    Undefined,
    is_rel,
    set2rel,
    arity,
    read_valuation,
)
from nltk.sem.logic import (
    boolean_ops,
    binding_ops,
    equality_preds,
    read_logic,
    Variable,
    Expression,
    ApplicationExpression,
    LogicalExpressionException,
)
from nltk.sem.skolemize import skolemize
from nltk.sem.lfg import FStructure
from nltk.sem.relextract import extract_rels, rtuple, clause
from nltk.sem.boxer import Boxer
from nltk.sem.drt import DrtExpression, DRS

# from nltk.sem.glue import Glue
# from nltk.sem.hole import HoleSemantics
# from nltk.sem.cooper_storage import CooperStore

# don't import chat80 as its names are too generic