nltk.sem.logic

module documentation

(source)

A version of first order predicate logic, built on top of the typed lambda calculus.

Class	`AbstractVariableExpression`	This class represents a variable to be used as a predicate or entity
Class	`AllExpression`	Undocumented
Class	`AndExpression`	This class represents conjunctions
Class	`AnyType`	Undocumented
Class	`ApplicationExpression`	This class is used to represent two related types of logical expressions.
Class	`BasicType`	Undocumented
Class	`BinaryExpression`	No class docstring; 0/1 property, 0/2 instance variable, 2/7 methods documented
Class	`BooleanExpression`	No class docstring; 1/1 method documented
Class	`ComplexType`	Undocumented
Class	`ConstantExpression`	This class represents variables that do not take the form of a single character followed by zero or more digits.
Class	`EntityType`	Undocumented
Class	`EqualityExpression`	This class represents equality expressions like "(x = y)".
Class	`EventType`	Undocumented
Class	`EventVariableExpression`	This class represents variables that take the form of a single lowercase 'e' character followed by zero or more digits.
Class	`ExistsExpression`	Undocumented
Class	`Expression`	This is the base abstract object for all logical expressions
Class	`FunctionVariableExpression`	This class represents variables that take the form of a single uppercase character followed by zero or more digits.
Class	`IffExpression`	This class represents biconditionals
Class	`ImpExpression`	This class represents implications
Class	`IndividualVariableExpression`	This class represents variables that take the form of a single lowercase character (other than 'e') followed by zero or more digits.
Class	`LambdaExpression`	No class docstring; 0/1 property, 1/2 method documented
Class	`LogicParser`	A lambda calculus expression parser.
Class	`NegatedExpression`	No class docstring; 0/1 property, 0/1 instance variable, 3/8 methods documented
Class	`OrExpression`	This class represents disjunctions
Class	`QuantifiedExpression`	No class docstring; 0/1 property, 1/2 method documented
Class	`SubstituteBindingsI`	An interface for classes that can perform substitutions for variables.
Class	`Tokens`	Undocumented
Class	`TruthValueType`	Undocumented
Class	`Type`	Undocumented
Class	`Variable`	No class docstring; 0/1 instance variable, 1/8 method documented
Class	`VariableBinderExpression`	This an abstract class for any Expression that binds a variable in an Expression. This includes LambdaExpressions and Quantified Expressions
Exception	`ExpectedMoreTokensException`	Undocumented
Exception	`IllegalTypeException`	Undocumented
Exception	`InconsistentTypeHierarchyException`	Undocumented
Exception	`LogicalExpressionException`	Undocumented
Exception	`TypeException`	Undocumented
Exception	`TypeResolutionException`	Undocumented
Exception	`UnexpectedTokenException`	Undocumented
Function	`binding_ops`	Binding operators
Function	`boolean_ops`	Boolean operators
Function	`demo`	Undocumented
Function	`demo_errors`	Undocumented
Function	`demoException`	Undocumented
Function	`equality_preds`	Equality predicates
Function	`is_eventvar`	An event variable must be a single lowercase 'e' character followed by zero or more digits.
Function	`is_funcvar`	A function variable must be a single uppercase character followed by zero or more digits.
Function	`is_indvar`	An individual variable must be a single lowercase character other than 'e', followed by zero or more digits.
Function	`printtype`	Undocumented
Function	`read_logic`	Convert a file of First Order Formulas into a list of {Expression}s.
Function	`read_type`	Undocumented
Function	`skolem_function`	Return a skolem function over the variables in univ_scope param univ_scope
Function	`typecheck`	Ensure correct typing across a collection of `Expression` objects. :param expressions: a collection of expressions :param signature: dict that maps variable names to types (or string representations of types)...
Function	`unique_variable`	Return a new, unique variable.
Function	`VariableExpression`	This is a factory method that instantiates and returns a subtype of `AbstractVariableExpression` appropriate for the given variable.
Constant	`ANY_TYPE`	Undocumented
Constant	`APP`	Undocumented
Constant	`ENTITY_TYPE`	Undocumented
Constant	`EVENT_TYPE`	Undocumented
Constant	`TRUTH_TYPE`	Undocumented
Variable	`_counter`	Undocumented

def binding_ops(): (source) ¶

Binding operators

def boolean_ops(): (source) ¶

Boolean operators

def demo(): (source) ¶

Undocumented

def demo_errors(): (source) ¶

Undocumented

def demoException(s): (source) ¶

Undocumented

def equality_preds(): (source) ¶

Equality predicates

def is_eventvar(expr): (source) ¶

An event variable must be a single lowercase 'e' character followed by zero or more digits.

Parameters
expr	str
Returns
bool True if expr is of the correct form

def is_funcvar(expr): (source) ¶

A function variable must be a single uppercase character followed by zero or more digits.

Parameters
expr	str
Returns
bool True if expr is of the correct form

def is_indvar(expr): (source) ¶

An individual variable must be a single lowercase character other than 'e', followed by zero or more digits.

Parameters
expr	str
Returns
bool True if expr is of the correct form

def printtype(ex): (source) ¶

Undocumented

def read_logic(s, logic_parser=None, encoding=None): (source) ¶

Convert a file of First Order Formulas into a list of {Expression}s.

Parameters
s:str	the contents of the file
logic_parser:LogicParser	The parser to be used to parse the logical expression
encoding:str	the encoding of the input string, if it is binary
Returns
list(Expression)	a list of parsed formulas.

def read_type(type_string): (source) ¶

Undocumented

def skolem_function(univ_scope=None): (source) ¶

Return a skolem function over the variables in univ_scope param univ_scope

def typecheck(expressions, signature=None): (source) ¶

Ensure correct typing across a collection of Expression objects. :param expressions: a collection of expressions :param signature: dict that maps variable names to types (or string representations of types)

def unique_variable(pattern=None, ignore=None): (source) ¶

Return a new, unique variable.

Parameters
pattern	`Variable` that is being replaced. The new variable must be the same type.
ignore	Undocumented
term	a set of `Variable` objects that should not be returned from this function.
Returns
Variable	Undocumented