Module Expr Str ImportFrom alias alias alias alias ImportFrom alias alias alias alias alias alias alias alias ImportFrom alias alias alias alias alias alias alias alias ImportFrom alias ImportFrom alias ImportFrom alias alias alias ImportFrom alias ImportFrom alias alias
N/A N/A 
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)
 nltk.sem.util parse_sents interpret_sents evaluate_sents root_semrep nltk.sem.evaluate Valuation Assignment Model Undefined is_rel set2rel arity read_valuation nltk.sem.logic boolean_ops binding_ops equality_preds read_logic Variable Expression ApplicationExpression LogicalExpressionException nltk.sem.skolemize skolemize nltk.sem.lfg FStructure nltk.sem.relextract extract_rels rtuple clause nltk.sem.boxer Boxer nltk.sem.drt DrtExpression DRS