Package nltk :: Package sem :: Module drt :: Class DRS

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type DRS

                   object --+    
                            |    
                  AbstractDrs --+
                                |
               object --+       |
                        |       |
logic.SubstituteBindingsI --+   |
                            |   |
             logic.Expression --+
                                |
                               DRS

A Discourse Representation Structure.

Instance Methods

__init__(self, refs, conds, consequent=None)

source code

replace(self, variable, expression, replace_bound=False, alpha_convert=True)
Replace all instances of variable v with expression E in self, where v is free in self.

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

get_refs(self, recursive=False)
Return the set of discourse referents in this DRS.

source code

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

source code

eliminate_equality(self)

source code

simplify(self)
Returns: beta-converted version of this expression

source code

fol(self)

source code

_pretty(self)

source code

_order_ref_strings(self, refs)

source code

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

source code

source code

Inherited from AbstractDrs: __add__, __and__, __gt__, __neg__, __or__, applyto, draw, equiv, is_pronoun_function, make_EqualityExpression, make_VariableExpression, pprint, pretty, resolve_anaphora, typecheck

Inherited from AbstractDrs (private): _get_type

Inherited from logic.Expression: __call__, __hash__, __lt__, __neq__, __repr__, findtype, negate, normalize, substitute_bindings, tp_equals

Inherited from logic.Expression (private): _set_type

Properties

Inherited from AbstractDrs: type

Method Details

init(self, refs, conds, consequent=None)
(Constructor)

Parameters:

refs - list of DrtIndividualVariableExpression for the discourse referents
conds - list of Expression for the conditions

Overrides: object.__init__

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

Replace all instances of variable v with expression E in self, where v is free in self.

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: logic.Expression.replace

variables(self)

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: logic.SubstituteBindingsI.variables

See Also: Expression.variables()

free(self, indvar_only=True)

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: logic.Expression.free

See Also: Expression.free()

get_refs(self, recursive=False)

Return the set of discourse referents in this DRS.

Parameters:

recursive - boolean Also find discourse referents in subterms?

Returns:

list of Variables

Overrides: AbstractDrs.get_refs

See Also: AbstractExpression.get_refs()

visit(self, function, combinator, default)

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: logic.Expression.visit

See Also: Expression.visit()

eliminate_equality(self)

Overrides: AbstractDrs.eliminate_equality

simplify(self)

Returns:: beta-converted version of this expression
Overrides: logic.Expression.simplify: (inherited documentation)

eq(self, other)
(Equality operator)

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

Overrides: logic.Expression.__eq__

str(self)
(Informal representation operator)

Overrides: logic.Expression.__str__