I am using the Jena semantic web framework version 2.6.3. I have code that creates a model with owl inferencing and then adds the following triples: [:bnode-3 rdf:type owl:Restriction] [:bnode-3 owl:onProperty :offspringOf] [:bnode-3 owl:someValuesFrom :Person] [:bnode-3 rdfs:subClassOf :Person] bnode-3 is supposed to be a restriction class which, for example, would contain :joe if :bob is a :Person and the following triple were asserted: [:joe :offspringOf :bob]. Then, since the restriction class is a subclass of Person, :joe would also be a person. And, in fact, this works. Whats confusing to me is that after I assert just the 4 triples at the top of this post, the inferencer creates a blank node which is a Person. In other words, the following triple is now in the model: [_:b0 rdf:type :Person] I don't understand why it would do this. Any help in understanding this would be greatly appreciated. Thanks. Kent.