DAML+OIL for Application Developers - slide "Subproperties"

in addition to subclasses, RDFS supports subproperties, e.g.


<rdfs:Property rdf:ID="parent"/>
<rdfs:Property rdf:ID="father">
  <rdfs:subPropertyOf rdf:about="#parent"/>
</rdfs:Property>
<rdfs:Property rdf:ID="mother">
  <rdfs:subPropertyOf rdf:about="#parent"/>
</rdfs:Property>

allows us define our data using mother and father, but then query on either mother, father, or parent