- From: Bijan Parsia <bparsia@cs.man.ac.uk>
- Date: Fri, 30 Nov 2007 15:05:24 +0000
- To: OWL WG <public-owl-wg@w3.org>
On 30 Nov 2007, at 10:19, Boris Motik wrote: > Hello, > > I would like to second Peter's sentiment, and would like to give > some concrete explanation why this is so. All sound and complete > reasoners for OWL DL that are currently out there do not use RDF- > based storage. Similarly, ontology APIs that are designed to work > with OWL DL, such as (Manchester) OWL API and KAON2, are likewise > not based at all on RDF, but on a storage mechanism that is quite > close to the metamodel presented in the structural specification > document. In these tools, RDF is used just as an exchange syntax. Having tried to do OWL stuff directly on RDF (back in the day), I will say that it imposes a cognitive/development burden on me that I'm not willing to accept. Thus, services like: justification finding diffing pretty printing modularity analysis, segmentation, etc. ontology complexity analysis normalization are things which, thus far, most significant (that I know of) theoretical, algorithmic, and implementation work has taken place at the axiom level. Indeed, a major reason for killing off the frame style stuff in the functional syntax is that that *got seriously in the way* when reflected down into the OWL API (it still might be ok for certain presentational purposes, natch). Many editors work at the axiom rather than triple level. The only serious focused-on-OWL editor for which I've seen a claim that this is *not* the case is TopBraid Composer. Unfortunately, it's closed source so I can't really tell you how it works inside. I struggle to imagine how it works except by having some higher level structures/ object model. Other people may have different experiences, but this is my experience and that of many the developers I've collaborated and chatted with. Obviously, there are cases where the triple representation and the higher level representation coincide or are very close...take subsumption between atomics. Then it really *doesn't* matter. But for anything moderately complex, esp. complex expressions (by which I just mean expressions :)) I have *no idea* how any of this affects or should inform the OMG work. I was solicited to review that work some months back, but I had neither time, nor energy, nor, I believe, relevant expertise. (I still struggle with what all this does or doesn't help me/allow me to do or what good practice is. I tend to think of "metamodels" as grammars in which case I have trouble understanding why I should pay attention to a particular grammar presentation. Elisa has helped me in private email, but I think it will take a while before I can comment usefully on the details.) I do think a fairly high level presentation is useful. I also, as I've said before, think more concrete specification in serialization would be helpful. For me, specs in terms of triples are not particularly useful (if only since I deal with many syntaxes other than triple based ones). I wrote this merely to provide information. I don't yet recognize that I have stake in keeping the diagrams or metamodel in W3C or not. Cheers, Bijan.
Received on Friday, 30 November 2007 15:04:00 UTC