edu.isi.powerloom.pl_kernel_kb.loom_api
Class LoomApi

java.lang.Object
  edu.isi.powerloom.pl_kernel_kb.loom_api.LoomApi

public class LoomApi
extends java.lang.Object

Field Summary

static Keyword	KWD_ASSERTED
static Keyword	KWD_AXIOMS
static Keyword	KWD_CONCEPTS
static Keyword	KWD_DIRECT
static Keyword	KWD_DOCUMENTATION
static Keyword	KWD_INSTANCES
static Keyword	KWD_RELATIONS
static Surrogate	SGT_LOOM_API_LOOM_ROLE
static Surrogate	SGT_LOOM_API_LOOM_ROLE_OF
static Symbol	SYM_LOOM_API_F_COVERINGp_QUERY_000
static Symbol	SYM_LOOM_API_F_FIND_OR_CREATE_LOOM_ROLE_QUERY_000
static Symbol	SYM_LOOM_API_F_GET_DOMAIN_QUERY_000
static Symbol	SYM_LOOM_API_F_GET_LOOM_ROLES_QUERY_000
static Symbol	SYM_LOOM_API_F_GET_PARTITIONS_QUERY_000
static Symbol	SYM_LOOM_API_F_GET_RANGE_QUERY_000
static Symbol	SYM_LOOM_API_F_GET_RELATION_INDUCED_ROLES_QUERY_000
static Symbol	SYM_LOOM_API_F_LIST_CONTEXT_QUERY_000
static Symbol	SYM_LOOM_API_F_LIST_CONTEXT_QUERY_001
static Symbol	SYM_LOOM_API_F_RELATION_OF_LOOM_ROLE_QUERY_000
static Symbol	SYM_LOOM_API_FRAME_PREDICATE
static Symbol	SYM_LOOM_API_INSTANCE_OF
static Symbol	SYM_LOOM_API_LOOM_ROLE_OF
static Symbol	SYM_LOOM_API_pCOVERED
static Symbol	SYM_LOOM_API_pD
static Symbol	SYM_LOOM_API_pFR
static Symbol	SYM_LOOM_API_pI
static Symbol	SYM_LOOM_API_pR
static Symbol	SYM_LOOM_API_pROLE
static Symbol	SYM_LOOM_API_pV
static Symbol	SYM_LOOM_API_STARTUP_LOOM_SUPPORT
static Symbol	SYM_PL_KERNEL_KB_COVERING
static Symbol	SYM_PL_KERNEL_KB_MUTUALLY_DISJOINT_COLLECTION

Constructor Summary

LoomApi()

Method Summary

static void	addRoleValue(Stella_Object instanceref, Stella_Object relationref, Stella_Object valueref) Assert the tuple '(relationRef instanceRef valueRef)'.
static void	addType(Stella_Object instanceref, Stella_Object classref) Assert that the instance referenced by 'instanceRef' is an instance of the class referenced by 'classRef'.
static void	assertLoomProposition(Cons loomsentence, boolean retractP) Convert each Loom sentence into a KIF equivalent and assert it or retract it.
static void	clearUserContexts() Destroy the contents of all non-system-defined modules.
static Cons	collectionMembers(Stella_Object instanceref) Return a list of concepts that belong to the collection 'instanceRef'.
static Description	computeConjunctionRelation(Cons relationrefs) Return a relation representing the conjunction of relations in 'relationRefs'.
static Module	contextOfInstance(Stella_Object instanceref) Return the home context (a module) of 'instanceRef', or NULL if it is not context sensitive.
static boolean	coveringP(Stella_Object instanceref, Stella_Object classref) Return TRUE if the mutually disjoint collection 'instanceRef' covers 'classRef'.
static Stella_Object	createInstance(Stella_Object instanceref, Stella_Object classref) Create an instance named 'instanceRef' of type 'classRef'.
static void	deleteInstance(Stella_Object instanceref) Destroy the instance, class or relation 'instanceRef'.
static boolean	disjointRelationsP(Stella_Object relationref1, Stella_Object relationref2) Return TRUE if 'relationRef1' and 'relationRef2' are disjoint.
static LogicObject	findClass(Stella_Object instanceref, Module module, boolean localP) Return the nearest class with name 'instanceRef' in the module 'module'.
static LogicObject	findOrCreateInstance(Stella_Object instanceref, Stella_Object classref) Find an existing instance refenced by 'instanceRef' of type 'classRef', or create one of type 'classRef'.
static LoomRole	findOrCreateLoomRole(Stella_Object instanceref, Stella_Object relationref, boolean createP) Return a LOOM-ROLE instance if 'instanceRef' has a Loom role named 'relationRef'.
static LogicObject	findRelation(Stella_Object instanceref, Module module, boolean localP) Return the nearest relation with name 'instanceRef' in the module 'module'.
static Stella_Object	generateSourceExpression(Stella_Object instanceref) Return an s-expression representing the source expression for 'instanceRef'.
static Cons	getChildContexts(Stella_Object moduleref) Return a list of child modules of 'moduleRef'.
static Cons	getClassInstances(Stella_Object classref, boolean directP) Return a list of instances belonging to the class 'classRef'.
static NamedDescription	getDomain(Stella_Object relationref) Return the domain of the binary relation 'relationRef'.
static Cons	getEquivalentNames(Stella_Object relationref) Return a list containing the name of 'relationRef' plus the names of any equivalent relations.
static Symbol	getInstanceName(Stella_Object instanceref) Return the name (a symbol) of the instance referenced by 'instanceRef'.
static Surrogate	getInstanceSurrogate(Stella_Object instanceref) Return the surrogate pointing to the instance referenced by 'instanceRef'.
static Cons	getLoomRoles(Stella_Object instanceref, boolean inferrolesP) Return a list of LOOM-ROLEs on 'instanceRef'.
static int	getMaxCardinality(Stella_Object instanceref, Stella_Object relationref) Infer a maximum cardinality for the set of fillers of the range of relation 'relationRef' applied to 'instanceRef'.
static int	getMinCardinality(Stella_Object instanceref, Stella_Object relationref) Infer a minimum cardinality for the set of fillers of the range of relation 'relationRef' applied to 'instanceRef'.
static Cons	getParentContexts(Stella_Object moduleref) Return a list of parent modules of 'moduleRef'.
static Cons	getPartitions(Stella_Object classref) Return a list of partitions that specify disjointness of children of the class classRef'.
static NamedDescription	getRange(Stella_Object relationref) Return the range of the binary relation 'relationRef'.
static Cons	getRelationInducedRoles(Stella_Object instanceref)
static Cons	getRoleDefaultValues(Stella_Object instanceref, Stella_Object relationref) Return a list of default values for the binary relation 'relationRef' applied to 'instanceRef'.
static Cons	getRoleNamesAndValues(Stella_Object instanceref) Return a list of lists, with each sublist containing a relation (role) name (a symbol) followed by one or more fillers of that role on 'instanceRef'.
static Stella_Object	getRoleValue(Stella_Object instanceref, Stella_Object relationref) Return a value for the binary relation 'relationRef' applied to 'instanceRef'.
static Cons	getRoleValues(Stella_Object instanceref, Stella_Object relationref) Return a list of values for the binary relation 'relationRef' applied to 'instanceRef'.
static Cons	getSubrelations(Stella_Object relationref, boolean directP) Return a list of relations that specialize 'relationRef'.
static Cons	getSuperrelations(Stella_Object relationref, boolean directP) Return a list of relations that generalize 'relationRef'.
static Cons	getTypes(Stella_Object instanceref, Keyword directorasserted) Return a list of classes that instance belongs to.
static Description	getValueRestriction(Stella_Object instanceref, Stella_Object relationref) Infer a type restriction on the set of fillers of the range of relation 'relationRef' applied to 'instanceRef'.
static Module	getXcontext(Stella_Object contextref) Return the module referenced by 'contextRef'.
static boolean	individualP(Stella_Object renamed_Object) Return TRUE if 'objectRef' is an instance or the name of an instance, and does not denote a relation, class, or set.
static boolean	instanceOfP(Stella_Object instanceref, Stella_Object classref) Return TRUE if the instance referenced by 'instanceRef' belongs to the class referenced by 'classRef'.
static boolean	instanceP(Stella_Object objectref) Return TRUE if 'objectRef' is an instance or the name of an instance.
static Cons	listContext(Module context, Keyword values)
static Cons	mostSpecificRelations(Cons relationrefs, boolean classifyfirstP) Return a list of the most specific among the relations in 'relationRefs'.
static boolean	namedP(Stella_Object instanceref) Return TRUE if the object returned by 'instanceRef' is matched with a logical constant.
static int	relationArity(Stella_Object relationref) Return the arity of the relation 'relationRef'.
static void	removeRoleValue(Stella_Object instanceref, Stella_Object relationref, Stella_Object valueref) Retract the tuple '(relationRef instanceRef valueRef)'.
static void	removeType(Stella_Object instanceref, Stella_Object classref) Retract that the instance referenced by 'instanceRef' is an instance of the class referenced by 'classRef'.
static Surrogate	safeSurrogatify(Stella_Object surrogateref)
static boolean	subrelationP(Stella_Object subrelationref, Stella_Object superrelationref) Return TRUE if 'subrelationRef' specializes 'superrelationRef'.
static void	updateRoleValue(Stella_Object instanceref, Stella_Object relationref, Stella_Object valueref, boolean assertP) Assert the tuple '(relationRef instanceRef valueRef)', or retract if 'assert?' is FALSE.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SGT_LOOM_API_LOOM_ROLE

public static Surrogate SGT_LOOM_API_LOOM_ROLE

SYM_LOOM_API_LOOM_ROLE_OF

public static Symbol SYM_LOOM_API_LOOM_ROLE_OF

KWD_DOCUMENTATION

public static Keyword KWD_DOCUMENTATION

KWD_AXIOMS

public static Keyword KWD_AXIOMS

SYM_LOOM_API_pI

public static Symbol SYM_LOOM_API_pI

SYM_LOOM_API_pR

public static Symbol SYM_LOOM_API_pR

SYM_LOOM_API_pROLE

public static Symbol SYM_LOOM_API_pROLE

SYM_LOOM_API_F_FIND_OR_CREATE_LOOM_ROLE_QUERY_000

public static Symbol SYM_LOOM_API_F_FIND_OR_CREATE_LOOM_ROLE_QUERY_000

SGT_LOOM_API_LOOM_ROLE_OF

public static Surrogate SGT_LOOM_API_LOOM_ROLE_OF

SYM_LOOM_API_F_GET_LOOM_ROLES_QUERY_000

public static Symbol SYM_LOOM_API_F_GET_LOOM_ROLES_QUERY_000

SYM_LOOM_API_pFR

public static Symbol SYM_LOOM_API_pFR

SYM_LOOM_API_pV

public static Symbol SYM_LOOM_API_pV

SYM_LOOM_API_FRAME_PREDICATE

public static Symbol SYM_LOOM_API_FRAME_PREDICATE

SYM_LOOM_API_INSTANCE_OF

public static Symbol SYM_LOOM_API_INSTANCE_OF

SYM_LOOM_API_F_GET_RELATION_INDUCED_ROLES_QUERY_000

public static Symbol SYM_LOOM_API_F_GET_RELATION_INDUCED_ROLES_QUERY_000

SYM_LOOM_API_F_RELATION_OF_LOOM_ROLE_QUERY_000

public static Symbol SYM_LOOM_API_F_RELATION_OF_LOOM_ROLE_QUERY_000

KWD_CONCEPTS

public static Keyword KWD_CONCEPTS

SYM_LOOM_API_F_LIST_CONTEXT_QUERY_000

public static Symbol SYM_LOOM_API_F_LIST_CONTEXT_QUERY_000

KWD_RELATIONS

public static Keyword KWD_RELATIONS

SYM_LOOM_API_F_LIST_CONTEXT_QUERY_001

public static Symbol SYM_LOOM_API_F_LIST_CONTEXT_QUERY_001

KWD_INSTANCES

public static Keyword KWD_INSTANCES

KWD_DIRECT

public static Keyword KWD_DIRECT

KWD_ASSERTED

public static Keyword KWD_ASSERTED

SYM_LOOM_API_pD

public static Symbol SYM_LOOM_API_pD

SYM_LOOM_API_F_GET_DOMAIN_QUERY_000

public static Symbol SYM_LOOM_API_F_GET_DOMAIN_QUERY_000

SYM_LOOM_API_F_GET_RANGE_QUERY_000

public static Symbol SYM_LOOM_API_F_GET_RANGE_QUERY_000

SYM_PL_KERNEL_KB_MUTUALLY_DISJOINT_COLLECTION

public static Symbol SYM_PL_KERNEL_KB_MUTUALLY_DISJOINT_COLLECTION

SYM_LOOM_API_F_GET_PARTITIONS_QUERY_000

public static Symbol SYM_LOOM_API_F_GET_PARTITIONS_QUERY_000

SYM_LOOM_API_pCOVERED

public static Symbol SYM_LOOM_API_pCOVERED

SYM_PL_KERNEL_KB_COVERING

public static Symbol SYM_PL_KERNEL_KB_COVERING

SYM_LOOM_API_F_COVERINGp_QUERY_000

public static Symbol SYM_LOOM_API_F_COVERINGp_QUERY_000

SYM_LOOM_API_STARTUP_LOOM_SUPPORT

public static Symbol SYM_LOOM_API_STARTUP_LOOM_SUPPORT

Constructor Detail

LoomApi

public LoomApi()

Method Detail

safeSurrogatify

public static Surrogate safeSurrogatify(Stella_Object surrogateref)

findOrCreateLoomRole

public static LoomRole findOrCreateLoomRole(Stella_Object instanceref,
                                            Stella_Object relationref,
                                            boolean createP)

Return a LOOM-ROLE instance if 'instanceRef' has a Loom role named 'relationRef'. If 'create?', create a role instance if one doesn't already exist.

Parameters:

instanceref -

relationref -

createP -

Returns:

LoomRole

getLoomRoles

public static Cons getLoomRoles(Stella_Object instanceref,
                                boolean inferrolesP)

Return a list of LOOM-ROLEs on 'instanceRef'. If 'inferRoles', create roles on the fly corresponding to frame predicate or domain propositions inherited by 'instance'.

Parameters:

instanceref -

inferrolesP -

Returns:

Cons

getRelationInducedRoles

public static Cons getRelationInducedRoles(Stella_Object instanceref)

getRoleNamesAndValues

public static Cons getRoleNamesAndValues(Stella_Object instanceref)

Return a list of lists, with each sublist containing a relation (role) name (a symbol) followed by one or more fillers of that role on 'instanceRef'.

Parameters:

instanceref -

Returns:

Cons

getXcontext

public static Module getXcontext(Stella_Object contextref)

Return the module referenced by 'contextRef'.

Parameters:

contextref -

Returns:

Module

getParentContexts

public static Cons getParentContexts(Stella_Object moduleref)

Return a list of parent modules of 'moduleRef'.

Parameters:

moduleref -

Returns:

Cons

getChildContexts

public static Cons getChildContexts(Stella_Object moduleref)

Return a list of child modules of 'moduleRef'.

Parameters:

moduleref -

Returns:

Cons

contextOfInstance

public static Module contextOfInstance(Stella_Object instanceref)

Return the home context (a module) of 'instanceRef', or NULL if it is not context sensitive.

Parameters:

instanceref -

Returns:

Module

clearUserContexts

public static void clearUserContexts()

Destroy the contents of all non-system-defined modules.

listContext

public static Cons listContext(Module context,
                               Keyword values)

relationArity

public static int relationArity(Stella_Object relationref)

Return the arity of the relation 'relationRef'.

Parameters:

relationref -

Returns:

int

findClass

public static LogicObject findClass(Stella_Object instanceref,
                                    Module module,
                                    boolean localP)

Return the nearest class with name 'instanceRef' in the module 'module'. If 'local?' is FALSE, also search modules inherited by 'module'. 'instanceRef' can be a string, symbol, or surrogate.

Parameters:

instanceref -

module -

localP -

Returns:

LogicObject

findRelation

public static LogicObject findRelation(Stella_Object instanceref,
                                       Module module,
                                       boolean localP)

Return the nearest relation with name 'instanceRef' in the module 'module'. If 'local?' is FALSE, also search modules inherited by 'module'. 'instanceRef' can be a string, symbol, or surrogate.

Parameters:

instanceref -

module -

localP -

Returns:

LogicObject

getInstanceSurrogate

public static Surrogate getInstanceSurrogate(Stella_Object instanceref)

Return the surrogate pointing to the instance referenced by 'instanceRef'.

Parameters:

instanceref -

Returns:

Surrogate

getInstanceName

public static Symbol getInstanceName(Stella_Object instanceref)

Return the name (a symbol) of the instance referenced by 'instanceRef'.

Parameters:

instanceref -

Returns:

Symbol

getEquivalentNames

public static Cons getEquivalentNames(Stella_Object relationref)

Return a list containing the name of 'relationRef' plus the names of any equivalent relations.

Parameters:

relationref -

Returns:

Cons

instanceP

public static boolean instanceP(Stella_Object objectref)

Return TRUE if 'objectRef' is an instance or the name of an instance.

Parameters:

objectref -

Returns:

boolean

individualP

public static boolean individualP(Stella_Object renamed_Object)

Return TRUE if 'objectRef' is an instance or the name of an instance, and does not denote a relation, class, or set.

Parameters:

renamed_Object -

Returns:

boolean

namedP

public static boolean namedP(Stella_Object instanceref)

Return TRUE if the object returned by 'instanceRef' is matched with a logical constant.

Parameters:

instanceref -

Returns:

boolean

createInstance

public static Stella_Object createInstance(Stella_Object instanceref,
                                           Stella_Object classref)

Create an instance named 'instanceRef' of type 'classRef'.

Parameters:

instanceref -

classref -

Returns:

Stella_Object

findOrCreateInstance

public static LogicObject findOrCreateInstance(Stella_Object instanceref,
                                               Stella_Object classref)

Find an existing instance refenced by 'instanceRef' of type 'classRef', or create one of type 'classRef'.

Parameters:

instanceref -

classref -

Returns:

LogicObject

instanceOfP

public static boolean instanceOfP(Stella_Object instanceref,
                                  Stella_Object classref)

Return TRUE if the instance referenced by 'instanceRef' belongs to the class referenced by 'classRef'.

Parameters:

instanceref -

classref -

Returns:

boolean

addType

public static void addType(Stella_Object instanceref,
                           Stella_Object classref)

Assert that the instance referenced by 'instanceRef' is an instance of the class referenced by 'classRef'.

Parameters:

instanceref -

classref -

removeType

public static void removeType(Stella_Object instanceref,
                              Stella_Object classref)

Retract that the instance referenced by 'instanceRef' is an instance of the class referenced by 'classRef'.

Parameters:

instanceref -

classref -

getTypes

public static Cons getTypes(Stella_Object instanceref,
                            Keyword directorasserted)

Return a list of classes that instance belongs to.

Parameters:

instanceref -

directorasserted -

Returns:

Cons

updateRoleValue

public static void updateRoleValue(Stella_Object instanceref,
                                   Stella_Object relationref,
                                   Stella_Object valueref,
                                   boolean assertP)

Assert the tuple '(relationRef instanceRef valueRef)', or retract if 'assert?' is FALSE.

Parameters:

instanceref -

relationref -

valueref -

assertP -

addRoleValue

public static void addRoleValue(Stella_Object instanceref,
                                Stella_Object relationref,
                                Stella_Object valueref)

Assert the tuple '(relationRef instanceRef valueRef)'.

Parameters:

instanceref -

relationref -

valueref -

removeRoleValue

public static void removeRoleValue(Stella_Object instanceref,
                                   Stella_Object relationref,
                                   Stella_Object valueref)

Retract the tuple '(relationRef instanceRef valueRef)'.

Parameters:

instanceref -

relationref -

valueref -

getRoleValue

public static Stella_Object getRoleValue(Stella_Object instanceref,
                                         Stella_Object relationref)

Return a value for the binary relation 'relationRef' applied to 'instanceRef'.

Parameters:

instanceref -

relationref -

Returns:

Stella_Object

getRoleValues

public static Cons getRoleValues(Stella_Object instanceref,
                                 Stella_Object relationref)

Return a list of values for the binary relation 'relationRef' applied to 'instanceRef'.

Parameters:

instanceref -

relationref -

Returns:

Cons

getRoleDefaultValues

public static Cons getRoleDefaultValues(Stella_Object instanceref,
                                        Stella_Object relationref)

Return a list of default values for the binary relation 'relationRef' applied to 'instanceRef'.

Parameters:

instanceref -

relationref -

Returns:

Cons

getClassInstances

public static Cons getClassInstances(Stella_Object classref,
                                     boolean directP)

Return a list of instances belonging to the class 'classRef'.

Parameters:

classref -

directP -

Returns:

Cons

subrelationP

public static boolean subrelationP(Stella_Object subrelationref,
                                   Stella_Object superrelationref)

Return TRUE if 'subrelationRef' specializes 'superrelationRef'. Side-effect: Upclassify 'subrelationRef'.

Parameters:

subrelationref -

superrelationref -

Returns:

boolean

getSuperrelations

public static Cons getSuperrelations(Stella_Object relationref,
                                     boolean directP)

Return a list of relations that generalize 'relationRef'. Does not include relations equivalent to 'relationRef'.

Parameters:

relationref -

directP -

Returns:

Cons

getSubrelations

public static Cons getSubrelations(Stella_Object relationref,
                                   boolean directP)

Return a list of relations that specialize 'relationRef'. Does not include relations equivalent to 'relationRef'.

Parameters:

relationref -

directP -

Returns:

Cons

mostSpecificRelations

public static Cons mostSpecificRelations(Cons relationrefs,
                                         boolean classifyfirstP)

Return a list of the most specific among the relations in 'relationRefs'. If 'classifyFirst?', insure that all relations are classified before filtering for most-specific.

Parameters:

relationrefs -

classifyfirstP -

Returns:

Cons

computeConjunctionRelation

public static Description computeConjunctionRelation(Cons relationrefs)

Return a relation representing the conjunction of relations in 'relationRefs'.

Parameters:

relationrefs -

Returns:

Description

getDomain

public static NamedDescription getDomain(Stella_Object relationref)

Return the domain of the binary relation 'relationRef'.

Parameters:

relationref -

Returns:

NamedDescription

getRange

public static NamedDescription getRange(Stella_Object relationref)

Return the range of the binary relation 'relationRef'.

Parameters:

relationref -

Returns:

NamedDescription

getMinCardinality

public static int getMinCardinality(Stella_Object instanceref,
                                    Stella_Object relationref)

Infer a minimum cardinality for the set of fillers of the range of relation 'relationRef' applied to 'instanceRef'.

Parameters:

instanceref -

relationref -

Returns:

int

getMaxCardinality

public static int getMaxCardinality(Stella_Object instanceref,
                                    Stella_Object relationref)

Infer a maximum cardinality for the set of fillers of the range of relation 'relationRef' applied to 'instanceRef'.

Parameters:

instanceref -

relationref -

Returns:

int

getValueRestriction

public static Description getValueRestriction(Stella_Object instanceref,
                                              Stella_Object relationref)

Infer a type restriction on the set of fillers of the range of relation 'relationRef' applied to 'instanceRef'.

Parameters:

instanceref -

relationref -

Returns:

Description

assertLoomProposition

public static void assertLoomProposition(Cons loomsentence,
                                         boolean retractP)

Convert each Loom sentence into a KIF equivalent and assert it or retract it.

Parameters:

loomsentence -

retractP -

deleteInstance

public static void deleteInstance(Stella_Object instanceref)

Destroy the instance, class or relation 'instanceRef'.

Parameters:

instanceref -

generateSourceExpression

public static Stella_Object generateSourceExpression(Stella_Object instanceref)

Return an s-expression representing the source expression for 'instanceRef'.

Parameters:

instanceref -

Returns:

Stella_Object

getPartitions

public static Cons getPartitions(Stella_Object classref)

Return a list of partitions that specify disjointness of children of the class classRef'.

Parameters:

classref -

Returns:

Cons

disjointRelationsP

public static boolean disjointRelationsP(Stella_Object relationref1,
                                         Stella_Object relationref2)

Return TRUE if 'relationRef1' and 'relationRef2' are disjoint.

Parameters:

relationref1 -

relationref2 -

Returns:

boolean

coveringP

public static boolean coveringP(Stella_Object instanceref,
                                Stella_Object classref)

Return TRUE if the mutually disjoint collection 'instanceRef' covers 'classRef'. If 'classRef' is NULL, return TRUE if 'instanceRef' covers some concept.

Parameters:

instanceref -

classref -

Returns:

boolean

collectionMembers

public static Cons collectionMembers(Stella_Object instanceref)

Return a list of concepts that belong to the collection 'instanceRef'.

Parameters:

instanceref -

Returns:

Cons