CODEWITHSUNDEEP
semantic-webowlprotege
Kar
Kar

Reputation: 6345

Declaring an empty class in OWL

Does OWL allow an ontology to contain just an empty class? Do classes have to contain some individuals? Does

<owl:Class rdf:ID="Human"/>

mean that "Human" is an empty class?

If an ontology contains an empty class, could the individuals be defined in another ontology that extends it?

Similarly, could an individual be declared without being a member of any class in an ontology?

Thanks

Upvotes: 2

Views: 438

Answers (1)

cygri
cygri

Reputation: 9472

Yes, you can declare an empty class.

Yes, you can declare individuals of such a class in a different ontology.

Both of these are completely normal. The idea of ontologies is that they can be shared, that is, one party defines the classes and properties, and then other parties can use it by actually instantiating the classes and using the properties to describe them.

Every individual is implicitly a member of the owl:Thing class. So the closest you can get to declaring an individual with no class is to make it a member of owl:Thing:

<owl:Thing rdf:ID="MyThing"/>

Upvotes: 2

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