nltk.sem.evaluate

module documentation

(source)

This module provides data structures for representing first-order models.

Class	`Assignment`	A dictionary which represents an assignment of values to variables.
Class	`Model`	A first order model is a domain D of discourse and a valuation V.
Class	`Valuation`	A dictionary which represents a model-theoretic Valuation of non-logical constants. Keys are strings representing the constants to be interpreted, and values correspond to individuals (represented as strings) and n-ary relations (represented as sets of tuples of strings).
Exception	`Error`	Undocumented
Exception	`Undefined`	Undocumented
Function	`arity`	Check the arity of a relation. :type rel: set of tuples :rtype: int of tuple of str
Function	`demo`	Run exists demos.
Function	`foldemo`	Interpretation of closed expressions in a first-order model.
Function	`folmodel`	Example of a first-order model.
Function	`is_rel`	Check whether a set represents a relation (of any arity).
Function	`propdemo`	Example of a propositional model.
Function	`read_valuation`	Convert a valuation string into a valuation.
Function	`satdemo`	Satisfiers of an open formula in a first order model.
Function	`set2rel`	Convert a set containing individuals (strings or numbers) into a set of unary tuples. Any tuples of strings already in the set are passed through unchanged.
Function	`trace`	Undocumented
Variable	`mult`	Undocumented
Function	`_read_valuation_line`	Read a line in a valuation file.
Constant	`_ELEMENT_SPLIT_RE`	Undocumented
Constant	`_TUPLES_RE`	Undocumented
Constant	`_VAL_SPLIT_RE`	Undocumented

def arity(rel): (source) ¶

Check the arity of a relation. :type rel: set of tuples :rtype: int of tuple of str

def demo(num=0, trace=None): (source) ¶

Run exists demos.

num = 1: propositional logic demo

num = 2: first order model demo (only if trace is set)

num = 3: first order sentences demo

num = 4: satisfaction of open formulas demo

any other value: run all the demos

Parameters
num	Undocumented
trace	trace = 1, or trace = 2 for more verbose tracing

def foldemo(trace=None): (source) ¶

Interpretation of closed expressions in a first-order model.

def folmodel(quiet=False, trace=None): (source) ¶

Example of a first-order model.

def is_rel(s): (source) ¶

Check whether a set represents a relation (of any arity).

Parameters
s:set	a set containing tuples of str elements
Returns
bool	Undocumented

def propdemo(trace=None): (source) ¶

Example of a propositional model.

def read_valuation(s, encoding=None): (source) ¶

Convert a valuation string into a valuation.

Parameters
s:str	a valuation string
encoding:str	the encoding of the input string, if it is binary
Returns
Valuation	a `nltk.sem` valuation

def satdemo(trace=None): (source) ¶

Satisfiers of an open formula in a first order model.

def set2rel(s): (source) ¶

Convert a set containing individuals (strings or numbers) into a set of unary tuples. Any tuples of strings already in the set are passed through unchanged.

For example:

set(['a', 'b']) => set([('a',), ('b',)])
set([3, 27]) => set([('3',), ('27',)])

Parameters
s:set	Undocumented
Returns
set of tuple of str	Undocumented

def trace(f, *args, **kw): (source) ¶

Undocumented

mult: int = (source) ¶

Undocumented

def _read_valuation_line(s): (source) ¶

Read a line in a valuation file.

Lines are expected to be of the form:

noosa => n
girl => {g1, g2}
chase => {(b1, g1), (b2, g1), (g1, d1), (g2, d2)}

Parameters
s:str	input line
Returns
tuple	a pair (symbol, value)

_ELEMENT_SPLIT_RE = (source) ¶

Undocumented

Value

re.compile(r'\s*,\s*')

_TUPLES_RE = (source) ¶

Undocumented

Value

re.compile('''\\s*
                                (\\([^)]+\\))  # tuple-expression
                                \\s*''',
           re.VERBOSE)

_VAL_SPLIT_RE = (source) ¶

Undocumented

Value

re.compile(r'\s*=+>\s*')