#include <FreeLink.h>

Inheritance diagram for opencog::FreeLink:

Collaboration diagram for opencog::FreeLink:

Public Member Functions
	FreeLink (const HandleSeq &oset, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	FreeLink (const Handle &a, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	FreeLink (Link &l)

virtual	~FreeLink ()

const HandleSeq &	get_vars (void)

virtual Handle	reduce (void)

Public Member Functions inherited from opencog::Link
	Link (Type t, const HandleSeq &oset, TruthValuePtr tv=TruthValue::DEFAULT_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	Link (Type t, const Handle &h, TruthValuePtr tv=TruthValue::DEFAULT_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	Link (Type t, const Handle &ha, const Handle &hb, TruthValuePtr tv=TruthValue::DEFAULT_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	Link (Type t, const Handle &ha, const Handle &hb, const Handle &hc, TruthValuePtr tv=TruthValue::DEFAULT_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	Link (Type t, const Handle &ha, const Handle &hb, const Handle &hc, const Handle &hd, TruthValuePtr tv=TruthValue::DEFAULT_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	Link (Link &l)

	~Link ()

Arity	getArity () const

const HandleSeq &	getOutgoingSet () const

Handle	getOutgoingAtom (Arity pos) const throw (RuntimeException)

template<class T >
bool	foreach_outgoing (bool(T::cb)(const Handle &), T data)

std::string	toString (std::string indent="")

std::string	toShortString (std::string indent="")

bool	isSource (Handle) const throw (InvalidParamException)

bool	isSource (size_t) const throw (IndexErrorException, InvalidParamException)

bool	isTarget (Handle) const throw (InvalidParamException)

bool	isTarget (size_t) const throw (IndexErrorException, InvalidParamException)

virtual bool	operator== (const Atom &) const

virtual bool	operator!= (const Atom &) const

Public Member Functions inherited from opencog::Atom
virtual	~Atom ()

Type	getType () const

bool	isType (Type t, bool subclass) const

Handle	getHandle ()

AttentionValuePtr	getAttentionValue ()

void	setAttentionValue (AttentionValuePtr)
	Sets the AttentionValue object of the atom. More...

AttentionValue::sti_t	getSTI ()
	Handy-dandy convenience getters for attention values. More...

AttentionValue::lti_t	getLTI ()

AttentionValue::vlti_t	getVLTI ()

void	setSTI (AttentionValue::sti_t stiValue)

void	setLTI (AttentionValue::lti_t ltiValue)

void	incVLTI ()

void	decVLTI ()

TruthValuePtr	getTruthValue ()

void	setTruthValue (TruthValuePtr)
	Sets the TruthValue object of the atom. More...

void	merge (TruthValuePtr)

Handle	tvmerge (TruthValuePtr tv)

size_t	getIncomingSetSize ()
	Get the size of the incoming set. More...

IncomingSet	getIncomingSet ()

template<typename OutputIterator >
OutputIterator	getIncomingSet (OutputIterator result)

template<class T >
bool	foreach_incoming (bool(T::cb)(const Handle &), T data)

template<typename OutputIterator >
OutputIterator	getIncomingSetByType (OutputIterator result, Type type, bool subclass=false)

IncomingSet	getIncomingSetByType (Type type, bool subclass=false)

Protected Member Functions
void	init (void)

void	find_vars (std::set< Handle > &, const HandleSeq &)

void	build_index (void)

	FreeLink (Type, const HandleSeq &oset, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	FreeLink (Type, const Handle &a, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

	FreeLink (Type, const Handle &a, const Handle &b, TruthValuePtr tv=TruthValue::NULL_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

Protected Member Functions inherited from opencog::Atom
	Atom (Type t, TruthValuePtr tv=TruthValue::DEFAULT_TV(), AttentionValuePtr av=AttentionValue::DEFAULT_AV())

void	keep_incoming_set ()

void	drop_incoming_set ()

void	insert_atom (LinkPtr)
	Add an atom to the incoming set. More...

void	remove_atom (LinkPtr)
	Remove an atom from the incoming set. More...

Protected Attributes
HandleSeq	_varseq

std::map< Handle, unsigned int >	_index

Protected Attributes inherited from opencog::Link
HandleSeq	_outgoing

Protected Attributes inherited from opencog::Atom
UUID	_uuid

AtomTable *	_atomTable

Type	_type

char	_flags

TruthValuePtr	_truthValue

AttentionValuePtr	_attentionValue

std::mutex	_mtx

InSetPtr	_incoming_set

Additional Inherited Members
Protected Types inherited from opencog::Atom
typedef std::shared_ptr< InSet >	InSetPtr

Detailed Description

The FreeLink records all of the free variables that occur within (underneath) it, in traversal order. Those variables are placed in sequential order in _varseq. An index is placed in _index. That is, given a variable, its ordinal number is placed in _index.

The FreeLink, as a base class, also provides an important method: reduce()

The reduce() method takes the given expression, and applies term reduction rules to obtain a smaller but equivalent expression. Ideally, the reduced expression is the "minimal" such expression. There is no guarantee that reduce is normalizing or strongly normalizing, but that does seem like a desirable goal.

An expression that contains free variables will contain the same free variables (or a subset of them) after reduction.

Note that both EvaluationLinks and ExecutionOutputLinks are reducible, and the result of reduction is always another Atom. This is in contrast to the concept of evaluation/execution: EvaluationLinks, when evaluated, yield truth values, while ExecutionOutputLinks, when executed, yield Atoms.

Definition at line 59 of file FreeLink.h.

Constructor & Destructor Documentation

FreeLink::FreeLink	(	Type	t,
		const HandleSeq &	oset,
		TruthValuePtr	tv = `TruthValue::NULL_TV()`,
		AttentionValuePtr	av = `AttentionValue::DEFAULT_AV()`
	)

protected

Definition at line 45 of file FreeLink.cc.

References opencog::classserver(), and init().

FreeLink::FreeLink	(	Type	t,
		const Handle &	a,
		TruthValuePtr	tv = `TruthValue::NULL_TV()`,
		AttentionValuePtr	av = `AttentionValue::DEFAULT_AV()`
	)

protected

Definition at line 58 of file FreeLink.cc.

References opencog::classserver(), and init().

FreeLink::FreeLink	(	Type	t,
		const Handle &	a,
		const Handle &	b,
		TruthValuePtr	tv = `TruthValue::NULL_TV()`,
		AttentionValuePtr	av = `AttentionValue::DEFAULT_AV()`
	)

protected

Definition at line 71 of file FreeLink.cc.

References opencog::classserver(), and init().

FreeLink::FreeLink	(	const HandleSeq &	oset,
		TruthValuePtr	tv = `TruthValue::NULL_TV()`,
		AttentionValuePtr	av = `AttentionValue::DEFAULT_AV()`
	)

Definition at line 29 of file FreeLink.cc.

References init().

FreeLink::FreeLink	(	const Handle &	a,
		TruthValuePtr	tv = `TruthValue::NULL_TV()`,
		AttentionValuePtr	av = `AttentionValue::DEFAULT_AV()`
	)

Definition at line 37 of file FreeLink.cc.

References init().

FreeLink::FreeLink ( Link & l )

Definition at line 84 of file FreeLink.cc.

References opencog::classserver(), opencog::Atom::getType(), and init().

virtual opencog::FreeLink::~FreeLink ( )

inlinevirtual

Definition at line 89 of file FreeLink.h.

Member Function Documentation

void FreeLink::build_index ( void )

protected

Build the index from variable name, to its ordinal number. The index is needed for variable substitution, i.e. for the reduce() method. The specific sequence order of the variables is essential for making substitution work.

Definition at line 129 of file FreeLink.cc.

References _index, and _varseq.

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void FreeLink::find_vars	(	std::set< Handle > &	varset,
		const HandleSeq &	oset
	)

protected

Create an ordered set of the free variables in this link.

By "ordered set" it is meant: a list of variables, in traversal order (from left to right, as they appear in the tree), with each variable being named only once. The varset is only used to make sure that we don't name a variable more than once; that's all.

Definition at line 103 of file FreeLink.cc.

References _varseq, opencog::LinkCast(), and python.undocumented.blocksworld::t.

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