> I think *if the ontology classifies reasonably at all*, then this > sort of query approach can achieve reasonable performance for this > rough application profile with a reasonable amount of engineering > effort in many cases.
Oh, but this is quite an important We can expect that most of the ontologies that are based on 'real data' are inconsistent, if not even highly inconsistent -- not because of errors on the side of the ontology designers, but because the represented information is contradictory. For example, we have found some inconsistency in one of our SenseLab OWL versions that was caused by the fact that the results of two experiments that were entered into the knowledge base were contradictory. Of course, this is a good example for the utility of an OWL reasoner, because it pointed us to a (potentially interesting or important) contradiction in the literature. However, such contradictions could lead a reasoning-based approach to querying fail, or at least they can make them less performant, as you said. cheers, Matthias Samwald . -- "Feel free" - 10 GB Mailbox, 100 FreeSMS/Monat ... Jetzt GMX TopMail testen: http://www.gmx.net/de/go/topmail
