In OWL, properties can have sub-properties, and some properties can be defined as the inverse of some other properties (i.e., through owl:inverseOf property).

To demonstrate the support for rdfs:subPropertyOf and owl:inverseOf reasoning, we will show how F-OWL can deduce correct conclusions from a set of premises.

This example is based on the animals.owl ontology, and the ontology statements are expressed in N3.

Premises: Both John and Mark are individuals of the Person class. Mark is the father of John, defined by the animals_hasFather property. This property is rdfs:subPropertyOf of animals_hasParent. Additionally, the animals_hasChild property is the inverse property of animals_hasParent.

animals:John a animals:Person.
animals:Mark a animals:Person ; animals:hasFather animals:John.
animals:hasFather rdfs:subPropertyOf animals:hasParent.
animals:hasChild owl:inverseOf animals:hasParent.

Conclusion: John has child Mark, and Mark has parent John.

animals:John animals:hasChild animals:Mark.
animals:Mark animals:hasParent animals:John.

The determine if the conclusion can be deduced by F-OWL, the following query can be used:

animals_John [animals_hasChild -> animals_Mark].

animals_Mark [animals_hasParent -> animals_John].

NOTE: the above example cannot be demonstrated in v0.3 due to a system bug in the underlying Flora-2/XSB implementation (05.11.2003).