An object property is one of two main categories of properties. It links individuals to individuals, and is defined as an instance of the built-in OWL class owl:ObjectProperty. This defines a property with the restriction that its values should be individuals.

An owl:ObjectProperty is a subclass of the RDF class rdf:Property



    <rdfs:Class rdf:ID="ObjectProperty">


        <rdfs:subClassOf rdf:resource="&rdf;Property"/>


Example listing




A property axiom defines characteristics of a property. In its simplest form, a property axiom just defines the existence of a property. For example:

    <owl:ObjectProperty rdf:ID="hasParent"/>

The second example below states that all instances (pairs) contained in the property extension of the property "hasMother" are also members of the property extension of the property "hasParent":

    <owl:ObjectProperty rdf:ID="hasMother">

        <rdfs:subPropertyOf rdf:resource="#hasParent"/>


Other information

In OWL Full, object properties and datatype properties are not disjoint. Because data values can be treated as individuals, datatype properties are effectively subclasses of object properties. In OWL Full owl:ObjectProperty is equivalent to rdf:Property In practice, this mainly has consequences for the use of owl:InverseFunctionalProperty.

We use the term "property extension" in a similar fashion to "class extension". The property extension is the set of instances that is associated with the property. Instances of properties are not single elements, but subject-object pairs of property statements. In relational database terms, property instances would be called "tuples" of a binary relation (the property).

Use in ISO 15926