- From: Jos De_Roo <jos.deroo.jd@belgium.agfa.com>
- Date: Tue, 10 Dec 2002 00:58:49 +0100
- To: Ian Horrocks <horrocks@cs.man.ac.uk>
- Cc: Jim Hendler <hendler@cs.umd.edu>, Jeremy Carroll <jjc@hplb.hpl.hp.com>, www-webont-wg@w3.org
> > > Jeremy's proposal is that OWL Lite be both a syntactic and *semantic* > > > "subset" (I use the expression loosely in this case) of OWL DL. > > > > > > Nothing loose there ... > > my proposal views a language as a pair: > > > > < A set of documents, > > an entailment relationship over the set > > > > > > > Then > > > > OWL DL is a sublanguage of OWL full > > in that the set of OWL DL documents is a subset of the set of OWL Full > > documents > > the OWL DL entailment relationship is a subset of the OWL Full > > entailment relationship (specifically the restriction of OWL Full > > entailment to the set of OWL DL documents). > > Yes, so an OWL DL reasoner, when asked about entailment between two > documents will either give the *SAME ANSWER* as an OWL full reasoner, > or will refuse to answer on the grounds that the document is outside > the subset it can handle. > > > > > My OWL Lite is a sublanguage of OWL Full > > the set of OWL Lite documents is a subset of the set of OWL Full documents > > the OWL Lite entailment relationship is also a subset of the OWL DL > > entailment relationship. > > You have omitted the crucial fact that, in the case of your OWL Lite > proposal, the entailment relationship is NOT the OWL full entailment > relationship restricted to the set of OWL Lite documents, but is > (probably) a subset of this set (intuitively tempting to believe that > this is the case, but it remains to be proved). Thus, OWL Lite > reasoners and OWL DL/full reasoners would give *DIFFERENT ANSWERS* to > questions about entailment w.r.t. OWL Lite documents. > > This is *NOT* simply incompleteness w.r.t. OWL DL/full semantics, > because a Lite reasoner would be entitled to answer NO to a question > about entailment when the correct DL/full answer is YES. Fine, then it should not say NO, but refuse to answer on the grounds that the *entailment relationship* is outside the subset it can handle. (to slightly twist your words) and that's just incompleteness -- , Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/
Received on Monday, 9 December 2002 18:59:28 UTC