- From: Bijan Parsia <bparsia@cs.man.ac.uk>
- Date: Wed, 7 Nov 2007 17:37:35 +0000
- To: Alan Ruttenberg <alanruttenberg@gmail.com>
- Cc: public-owl-wg@w3.org
On 7 Nov 2007, at 17:25, Alan Ruttenberg wrote: > On Oct 31, 2007, at 9:01 AM, Bijan Parsia wrote: > >> 3) Language extensions with "must understand". >> >> In C&P's implementation of probabilisitc extensions to OWL based >> on the P-SHOQ formalism, >> >> <http://clarkparsia.com/weblog/category/semweb/probabilistic- >> reasoning/> >> >> we used axiom annotations to turn subclass axioms into conditional >> constraints (for example). A system cannot *correctly* ignore >> those annotations, but it was a very convenient way to extend the >> language (although one could argue that it was potentially >> misleading): We didn't have to change any basic parsers or >> editors; it worked in all syntaxes for free, etc. >> >> In general, better support for extensions is helpful. > > I'm a little worried about this, one, in the sense that the file > advertises itself as OWL, but really isn't (it has different > semantics). Well, that's what you get from extending the language. From a Protege POV (the editor) this is fine. From the reasoner POV, it isn't. The mustUnderstand clearly indicates that Protege can hack it but FaCT++ can't. This is a pretty standard extensibility mechanism. > I'd worry that we would arrive at a situation in which there were > all sorts of little "must understand" bits from different people, > leading to one of two situations - either all should be rejected by > reasoners, or the "what the heck, it's just a couple of axioms, > let's ignore it". Care is needed, but this way at least some tools can do something sensible. > Would an alternative to define a different sort of file that has a > way of embedding OWL, and then teach tools to use those files too? Six of one, half a dozen of the other, AFAICT. And then protege wouldn't work so well with the new files. Shrug. Cheers, Bijan.
Received on Wednesday, 7 November 2007 17:36:10 UTC