More OWL reading.

Discussion with TJ and AN today revealed that AN isn't as enamoured of Jena as I thought. Basically, everything is still so immature that it's perfectly feasible to do it better... or at least do it differently in such a way as to allow Kowari and TKS to be accessed more efficiently that with any other existing API.

Got a better idea of OWL in my reading today. I wasn't quite getting how to apply an OWL ontology to real data. The whole OWL language is geared around describing data with no mention about how to apply the data. AN cleared that up. When data is loaded then the inferencing engine looks at the RDF and determines the classes for data based on the ontology. So for the camera ontology, there would be no mention that a Pentax OptioS is a digital camera, but the fact that you don't look through the viewfinder, that it meets all the requirements of a camera, etc, means that the inferencing engine can work out for itself that we're talking about a camera, and that it's a digital camera. This is why some operations in OWL are not guaranteed to be computable.

One would be tempted to infer these statements (such as "OptioS is a Digital Camera") and store them alongside the other data, but that has its problems as well. For a start, not everything can be inferred, so where do you stop? It also makes changes to the data or the schema quite problematic, as many inferred statements will no longer apply, but it may not be possible to find them again.

Inferencing types in particular sounds a little intimidating. I'll have to spend more time on this. I was under the impression that we needed to enforce the rules, but now I understand that we need to look at the data and determine if it follows the rules or not. That's a totally different problem. After going through the rest of the OWL docs I'll have to look at the Jena inferencing engine and see if I can learn anything from it.

Long weekend coming up again. I'll be spending it reading OWL, Fast Food Nation, and if I can I'll also get back to the USB design book that I'm also reading.