Package nltk :: Package sem :: Module logic :: Class VariableBinderExpression

type VariableBinderExpression

         object --+        
                  |        
SubstituteBindingsI --+    
                      |    
             Expression --+
                          |
                         VariableBinderExpression

Known Subclasses:

This an abstract class for any Expression that binds a variable in an Expression. This includes LambdaExpressions and Quantified Expressions

Instance Methods

[hide private]

__init__(self, variable, term)

source code

replace(self, variable, expression, replace_bound=False, alpha_convert=True)
Replace every instance of 'variable' with 'expression'

source code

alpha_convert(self, newvar)
Rename all occurrences of the variable introduced by this variable binder in the expression to @newvar. source code

variables(self)
Return a set of all the variables that are available to be replaced.

source code

free(self, indvar_only=True)
Return a set of all the free (non-bound) variables in self.

source code

findtype(self, variable)
@see Expression.findtype()

source code

visit(self, function, combinator, default)
Recursively visit sub expressions

source code

__eq__(self, other)
Defines equality modulo alphabetic variance.

source code

Inherited from Expression: __and__, __call__, __gt__, __hash__, __lt__, __neg__, __neq__, __or__, __repr__, __str__, applyto, equiv, make_VariableExpression, negate, normalize, simplify, substitute_bindings, tp_equals, typecheck

Inherited from Expression (private): _set_type

Method Details

[hide private]

init(self, variable, term)
(Constructor)

source code

Parameters:

variable - Variable, for the variable
term - Expression, for the term

Overrides: object.__init__

replace(self, variable, expression, replace_bound=False, alpha_convert=True)

source code

Replace every instance of 'variable' with 'expression'

Parameters:

variable - Variable The variable to replace
expression - Expression The expression with which to replace it
replace_bound - boolean Should bound variables be replaced?

Overrides: Expression.replace

See Also: Expression.replace()

alpha_convert(self, newvar)

source code

Rename all occurrences of the variable introduced by this variable binder in the expression to @newvar.

Parameters:

newvar - Variable, for the new variable

variables(self)

source code

Return a set of all the variables that are available to be replaced. This includes free (non-bound) variables as well as predicates.

Returns:: set of Variables
Overrides: SubstituteBindingsI.variables

See Also: Expression.variables()

free(self, indvar_only=True)

source code

Return a set of all the free (non-bound) variables in self. Variables serving as predicates are not included.

Parameters:

indvar_only - boolean only return individual variables?

Returns:

set of Variables

Overrides: Expression.free

See Also: Expression.free()

findtype(self, variable)

source code

@see Expression.findtype()

Parameters:

variable - Variable

Overrides: Expression.findtype

visit(self, function, combinator, default)

source code

Recursively visit sub expressions

Parameters:

function - Function to call on each sub expression
combinator - Function to combine the results of the function calls

Returns:

result of combination

Overrides: Expression.visit

See Also: Expression.visit()

eq(self, other)
(Equality operator)

source code

Defines equality modulo alphabetic variance. If we are comparing \x.M and \y.N, then check equality of M and N[x/y].

Overrides: Expression.__eq__

type VariableBinderExpression

__init__(self, variable, term) (Constructor)

replace(self, variable, expression, replace_bound=False, alpha_convert=True)

alpha_convert(self, newvar)

variables(self)

free(self, indvar_only=True)

findtype(self, variable)

visit(self, function, combinator, default)

__eq__(self, other) (Equality operator)

init(self, variable, term)
(Constructor)

eq(self, other)
(Equality operator)