Subproperties

Subproperties are a way to organize properties into a hierarchy, where a subproperty expresses a more specific relation than its superproperty. In RDF Schema (RDFS) and OWL, relationships between properties are declared using rdfs:subPropertyOf. This enables reasoning and query expansion: data written with a specific property can be treated as though it were also described by the more general property. For example, ex:hasPhoneNumber rdfs:subPropertyOf ex:hasContactInfo.

Semantics: If p rdfs:subPropertyOf q, then every triple with p as the predicate is also a triple with q as the predicate (p(s,o) implies q(s,o)). The relation is transitive: if p rdfs:subPropertyOf q and q rdfs:subPropertyOf r, then p rdfs:subPropertyOf r as well. Domain and range constraints can propagate: if q has domain D, then for any p(s,o) with p rdfs:subPropertyOf q, s is inferred to be a member of D; similarly, if q has range E, o is inferred to be a member of E. If p has its own domain or range, those constraints may also apply.

Applications: Subproperties support ontology modeling, data integration, and flexible querying by exploiting property hierarchies. They are widely used in metadata schemas and semantic datasets to avoid duplicating data while enabling generalization. In OWL, subproperty relations are part of a broader property hierarchy and may interact with other features such as property characteristics and property chains. Reasoners implement rdfs:subPropertyOf semantics according to the RDF Schema specification.