16.14.2. Making Rule Sets

Since RDF Schema and OWL schemas are RDF graphs, these can be loaded into the triple store. Thus, in order to use such a schema as query context, one first loads the corresponding document into the triple store using ttlp() or rdf_load_rdfxml() or related functions. After the schema document is loaded, one can add the assertions there into an inference context with the rdfs_rule_set() function. This function specifies a logical name for the rule set plus a graph URI. It is possible to combine multiple schema graphs into a single rule set. A single schema graph may also independently participate in multiple rule sets.

The DB.DBA.SYS_RDF_SCHEMA table contains information for all RDF rule sets in a Virtuoso instance. This table may be queried to, for instance, verify rdfs_rule_set() activity:

  RS_NAME VARCHAR,  -- The name of the rdf rule set
  RS_URI  VARCHAR,  -- The name of the graph
  RS_G    VARCHAR,  -- Column for system usage only