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My last posting Designing An Ontology In OWL - Using A Domain Or Range dealt with the domain and range values on properties. Consider a class Author and a property is_author_of that has a domain of Author. This means that it maps Authors to the thing that they authored. Using the property, therefore, allows an inference engine to determine that an individual is of type Author because it has the property is_author_of.

Designing an Ontology (using the Web Ontology Language – OWL) can be a difficult thing. Creating a model is difficult on its own, and it is further complicated by the subtleties of the language. Consider an Ontology with the following classes and properties

• Class Cat


• Class Dog


• Class Person


• Class Male is subclass of Person


• Class Female is subclass of Person


• Object Property Has_Brother maps a Person (domain) to a Male (range)


• Object Property Has_Sister maps a Person (domain) to a Female (range)


• Person Bob