InstanceOf Relation

An InstanceOf Relation is an IsA relation where the subclass does not have other IsA relations.

• AKA: instanceOf, InstanceOf Semantic Relation, ExampleOf.
• Context:
  • It can range from being a DirectInstanceOf Relation to being an IndirectInstanceOf Relation.
  • It can be to a Basic Concept or to a Physical Instance.
  • Its use in an Ontology can help with algorithm implementation.
• Example(s):
  • InstanceOf(Denotation, Reference Relation) ⇒ True.
  • InstanceOf(Gabor Melli, Animal) ⇒ True.
  • InstanceOf(Cyc, Human) ⇒ False, (a false relation).
  • a Semantic Relation Ontology.
  • InstanceOf(Human, Animal) ⇒ False. ??
• Counter-Example(s):
  • f(Human, Animal) ⇒ False; because the members are not Basic Concepts.
• See: Ground Fact, Entity Database, Example, Description Logic.

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References

2013

• http://en.wikipedia.org/wiki/Entity%E2%80%93relationship_model#The_building_blocks:_entities.2C_relationships.2C_and_attributes
  • … An entity-type is a category. An entity, strictly speaking, is an instance of a given entity-type. There are usually many instances of an entity-type. Because the term entity-type is somewhat cumbersome, most people tend to use the term entity as a synonym for this term.

• http://www-ksl.stanford.edu/knowledge-sharing/ontologies/html/frame-ontology/DIRECT-INSTANCE-OF.html
  • An individual i is an DIRECT-INSTANCE-OF class C if i is an instance-of C and there is no other subclass of C defined in the current ontology of which i is also an instance-of. Such a class C is a `minimal' or `most-specific' parent class for the individual i. The direct class is not necessarily unique; an individual can have several most-specific classes. Note that this relation is indexical -- its truth depends the contents of the current knowledge base rather than the world.

    The distinction between INSTANCE-OF and DIRECT-INSTANCE-OF is not the same as the relationship between asserting instance-of directly and having the system infer it. The meanings of both instance-of and direct-instance-of, and every other object-level relation in a knowledge base mean, are independent of whether they are asserted explicitly or inferred.

    Cyc makes the distinction between #%instanceOf and #%allInstanceOf. #%allInstanceOf means the same thing as INSTANCE-OF in our ontology. However, #%instanceOf is subtlely different from direct-instance-of. When someone asserts (#%instanceOf i C) to Cyc, it means the same thing as (#%allInstanceOf i C), but Cyc creates a pointer between an instance unit and a collection unit. Later, someone may define a subclass C_sub of C and assert (#%instanceOf i C_sub), and this is consistent with the earlier #%instanceOf assertion.

    Direct-instance-of is useful for maintaining a class hierarchy in a modular, canonical form. It is defined here because some systems maintain direct-instance-of and some applications depend on this.

• http://www.geneontology.org/GO.ontology.relations.shtml
  • It should be noted that is a does not mean ‘is an instance of’. An ‘instance’, ontologically speaking, is a specific example of something; e.g. a cat is a mammal, but Garfield is an instance of a cat, rather than a subtype of cat. GO, like most ontologies, does not use instances, and the terms in GO represent a class of entities or phenomena, rather than specific manifestations thereof. However, if we know that cat is a mammal, we can say that every instance of cat is a mammal.

• http://en.wikipedia.org/wiki/Instance_%28computer_science%29
  • An instance, in object-oriented programming (OOP), is a specific realization of any object. An object may be varied in a number of ways. Each realized variation of that object is an instance. The creation of a realized instance is called instantiation. Each time a program runs, it is an instance of that program.

2009

• http://www.w3.org/TR/WD-rdf-syntax-971002/
  • To help in reifying properties, RDF defines the InstanceOf relation (property) to provide primitive typing, as shown in the previous example.
  • The formal definition of InstanceOf is:
    • 1. There is an element of P known as RDF:InstanceOf.
    • 2. Elements of T that have RDF:InstanceOf as the first value in the 3-tuple must have elements of N as their second value and third values

• TBD
  • DL axioms are statements that describe relations between class (property) descriptions characteristics of properties, such as asserting a

property is transitive instanceOf relations between (pairs of) individuals and classes (properties).

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