- From: Ian Horrocks <ian.horrocks@comlab.ox.ac.uk>
- Date: Mon, 19 May 2008 19:14:02 +0100
- To: Michael Schneider <schneid@fzi.de>
- Cc: "Web Ontology Language ((OWL)) Working Group WG" <public-owl-wg@w3.org>, Jeremy Carroll <jjc@hpl.hp.com>
I talked to Peter about this and we agreed that Jeremy's proposal looks promising. I would like to hear from Michael as to what he thinks about this proposal. Ian On 28 Apr 2008, at 16:55, Jeremy Carroll wrote: > > We have discussed a different approach to comprehension, which was > perhaps poorly branded as 'solipistic' .... > > Peter and others have described this as a big change; the point of > this message is to argue to the contrary that it is small - both in > the amount of text of the spec that changes, and in the amount of > code that changes as a result. In fact, I suggest that 0-lines of > code change. Hence, this would be a backward compatible change. > > ===== > > > Current state OWL1: > > > + Comprehension principles + Theorem 2 > > These give a weak alignment of DL entailment and Full entailment > > Full reasoners (such as Jena Rules) partially implement this, by in > some circumstances introducing terms that match the constructs in > the comprehension principles. > > > Possible alternative: > > Comprehension principles remain, not as model theoretic principles, > but as reasoning principles. > > Theorem 2 is modified from approx: > > If A DL-entails B where A and B are in the syntactic subset then > A Full-entails B. > > To approx. > > If A DL-entails B where > A and B are in the syntactic subset > then > B = B' & B'' > where B'' is a conjunct of terms matching comprehension principles > and > A & B'' Full-entails B > > > ===== > > This modifies the comprehension principles from being model- > theoretic statements, to play a role in theorem 2 that speaks more > to the proof-theory. Since OWL Full implementations implement rules > (i.e. proofs) this proof-theoretic variant of comprehension is > closer to what the implementations already do, and there is no > backward compatibility problem. (Backward compatibility is about > OWL implementations and OWL documents, not about OWL specifications). > > Also, the textual change to the spec is slight - the comprehension > principles remain - but their role in the OWL Full semantics is > modified. > > > Jeremy > > > > >
Received on Monday, 19 May 2008 18:14:51 UTC