Virtuoso SPARQL can use an inference context for inferring triples that are not physically stored. This functionality applies to physically stored quads and not to virtual triples generated from relational data with Linked Data Views. Such an inference context can be built from one or more graphs containing RDF Schema triples. The supported RDF Schema or OWL constraints are imported from these graphs and are grouped together into rule bases. A rule base is a persistent entity that can be referenced by a SPARQL query or end point. Queries running with a given rule base work as if the triples asserted by this rule base were included in the graph or graphs accessed by the query.

As of version 5.0, Virtuoso recognizes rdfs:subClassOf and rdfs:subPropertyOf . owl:sameAs is considered for arbitrary subjects and objects if specially enabled by a pragma in the query. As of 5.00.3031, owl:sameAs, owl:equivalentClass and owl:equivalentProperty are also considered when determining subclass or subproperty relations. If two classes are equivalent, they share all instances, subclasses and superclasses directly or indirectly stated in the data for either class. Other RDF Schema or OWL information is not taken into account.