- From: Dan Connolly <connolly@w3.org>
- Date: 22 Apr 2002 17:41:53 -0500
- To: Jonathan Borden <jonathan@openhealth.org>
- Cc: "Peter F. "Patel-Schneider <pfps@research.bell-labs.com>, Jeremy Carroll <jjc@hplb.hpl.hp.com>, www-webont-wg@w3.org
On Mon, 2002-04-22 at 16:57, Jonathan Borden wrote: > Dan, > > (changing the subject because the thread is getting long, and I am > introducing a new question later on)... > > > At a glance, I'm pretty sure I could live with a theory > > of classes that was too weak to deal with that thing, at least > > for a few years. But I'll have to mull it over. > > That worries me. The cost seems to be "dark triples" which are simple to > deal with in the RDF MT, and there are relatively simple syntactic > constructs which can encode them. I don't understand 'dark triples' well enough to estimate their cost at anything lower than 'unbounded'. In particular, the costs outlined in Problems with dark triples approach From: Jeremy Carroll (jjc@hplb.hpl.hp.com) Date: Wed, Apr 17 2002 http://lists.w3.org/Archives/Public/www-webont-wg/2002Apr/0132.html are unacceptable to me. > I also note that RDF M&S has language > which indicates that 'reification' is to be used for something like 'dark > triples', but of course reification was intended to be used for a variety of > purposes, it just seems that providing something that was in RDF M&S in > perhaps a slightly different form, isn't all that out of charter. > > My fear is a 'theory of classes' that is too weak to do real world tasks, > particularly those that _already use description logic_. Medical > applications should be a slam dunk for OWL, it would be a real shame if the > language were crippled to the point of losing that. Well, some medical applications should be a slam dunk for OWL, yes. Whether all of them need to be a slam dunk for OWL 1.0 -- even all of the ones supported by DL reasoners -- I'm not so sure. I wouldn't expect anybody to take my word over yours about what the medical community needs, however. I'm only talking about the applications I intend to build/deploy: automating W3C process/operations, calendaring/scheduling, that sort of thing. > But beyond that, suppose we cripple the language, even then we aren't sure > that the solipsistic semantics will layer correctly on RDF i.e. won't > introduce yet some other paradox. Huh? I'm quite confident that the solipsistic semantics introduces no paradoxes. > Of course we could spend another 6 months > trying to work that out... It seems a much more efficient use of the time > and energy of the combined RDFCore+WebOnt team to fix this problem and move > on. Dark triples is the only proposal on the table for which there appears > any sort of consensus that it would actually work. Please point me to this dark triples proposal -- the one that explains how they work. I'm pretty sure there isn't one, and I've done quite a bit of looking (and phoning people, and so on.) [...] > > > <Restriction rdf:ID="PaternalDominantInheritance"> > > > <onProperty rdf:resource="#father"> > > > <toClass rdf:resource="#PaternalDominantInheritance"> > > > </Restriction> > > > > I don't think that's what you meant. > > > > That says that PaternalDominantInheritance is *exactly* > > those things whose fathers have type PaternalDominantInheritance; > > that there are no other conditions (like actually > > having a disease) for being in this class. > > > > I think you meant that PaternalDominantInheritance > > is a *subClass* of the (father hasClass PaternalDominantInheritance) > > restriction, right? > > > > OK, that's still circular, but it's a "primitive" class; > > i.e. you're going to be able to communicate to the > > machine *necessary* conditions for being in this class, > > but not *sufficient* condidions, right? > > > > I don't quite get "primitive" vs. "defined" to be honest. I understand the > necessary and sufficient, That's all there is to it. (that is: assuming *I* understand it!) > but for example: > > <Restriction rdf:ID="BlueThing"> > <onProperty rdf:resource="#color"/> > <toValue>blue</toValue> > </Restriction> > > That is primitive, right? nope. It's defined. > I don't get why it would be wrong to label > _anything_ which has the property color="blue" as a :BlueThing. it wouldn't. > I mean > anything can have any number of super classes, right? yes. > Is primitive vs. > defined simply an 'implementation' mechanism of reducing the number of > classes a thing belongs to? i.e. are "defined" classes, classes that you are > telling the system that you want it to make inferences on etc.? Otherwise > what is the harm of letting things be members of the instance sets of > primitive classes? There's no harm; I just didn't think you meant to say that there were no other conditions for being in the PaternalDominantInheritance class... I presume one has to actually have some disease to be in that class. -- Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Monday, 22 April 2002 18:43:03 UTC