nltk.inference.nonmonotonic.ClosedWorldProver

class documentation

class ClosedWorldProver(ProverCommandDecorator): (source)

Constructor: ClosedWorldProver(proverCommand)

This is a prover decorator that completes predicates before proving.

If the assumptions contain "P(A)", then "all x.(P(x) -> (x=A))" is the completion of "P". If the assumptions contain "all x.(ostrich(x) -> bird(x))", then "all x.(bird(x) -> ostrich(x))" is the completion of "bird". If the assumptions don't contain anything that are "P", then "all x.-P(x)" is the completion of "P".

walk(Socrates) Socrates != Bill + all x.(walk(x) -> (x=Socrates)) ---------------- -walk(Bill)

see(Socrates, John) see(John, Mary) Socrates != John John != Mary + all x.all y.(see(x,y) -> ((x=Socrates & y=John) | (x=John & y=Mary))) ---------------- -see(Socrates, Mary)

all x.(ostrich(x) -> bird(x)) bird(Tweety) -ostrich(Sam) Sam != Tweety + all x.(bird(x) -> (ostrich(x) | x=Tweety)) + all x.-ostrich(x) ------------------- -bird(Sam)

Method	`assumptions`	List the current assumptions.
Method	`_make_antecedent`	Return an application expression with 'predicate' as the predicate and 'signature' as the list of arguments.
Method	`_make_predicate_dict`	Create a dictionary of predicates from the assumptions.
Method	`_make_unique_signature`	This method figures out how many arguments the predicate takes and returns a tuple containing that number of unique variables.
Method	`_map_predicates`	Undocumented

Inherited from ProverCommandDecorator:

Method	`__init__`	No summary
Method	`decorate_proof`	Modify and return the proof string :param proof_string: str the proof to decorate :param simplify: bool simplify the proof? :return: str
Method	`get_prover`	Return the prover object :return: `Prover`
Method	`proof`	Return the proof string :param simplify: bool simplify the proof? :return: str
Method	`prove`	Perform the actual proof.
Instance Variable	`_proof`	Undocumented
Instance Variable	`_result`	Undocumented

Inherited from TheoremToolCommandDecorator (via ProverCommandDecorator):

Method	`add_assumptions`	Add new assumptions to the assumption list.
Method	`goal`	Return the goal
Method	`print_assumptions`	Print the list of the current assumptions.
Method	`retract_assumptions`	Retract assumptions from the assumption list.
Instance Variable	`_command`	Undocumented

def assumptions(self): (source) ¶

overrides nltk.inference.api.TheoremToolCommandDecorator.assumptions

List the current assumptions.

Returns
list of `Expression`

def _make_antecedent(self, predicate, signature): (source) ¶

Return an application expression with 'predicate' as the predicate and 'signature' as the list of arguments.

def _make_predicate_dict(self, assumptions): (source) ¶

Create a dictionary of predicates from the assumptions.

Parameters
assumptions	a list of ``Expression``s
Returns
dict mapping `AbstractVariableExpression` to `PredHolder`

def _make_unique_signature(self, predHolder): (source) ¶

This method figures out how many arguments the predicate takes and returns a tuple containing that number of unique variables.

def _map_predicates(self, expression, predDict): (source) ¶

Undocumented