From: Dan Connolly <connolly@w3.org>

Date: 20 Jun 2002 10:55:17 -0500

To: "Peter F. "Patel-Schneider <pfps@research.bell-labs.com>

Cc: www-webont-wg@w3.org

Message-Id: <1024588517.26130.1457.camel@dirk>

Date: 20 Jun 2002 10:55:17 -0500

To: "Peter F. "Patel-Schneider <pfps@research.bell-labs.com>

Cc: www-webont-wg@w3.org

Message-Id: <1024588517.26130.1457.camel@dirk>

On Wed, 2002-06-19 at 17:21, Peter F. Patel-Schneider wrote: > Good. A proposal. thanks for the quick feedback... > > From: Dan Connolly <connolly@w3.org> > Subject: layering (5.3,5.10): a first-order same-syntax model theory > Date: 19 Jun 2002 16:26:58 -0500 > > [...] > > > Additionally, owl reserves the following vocabulary: > > [...] > > I have no idea what ``reserves the ... vocabulary'' could mean. basically, it means that these symbols denote something in every OWL interpretation. I guess the allusion to [RDFMT] wasn't sufficiently explicit... "An interpretation assigns meanings to symbols in a particular vocabulary of urirefs. Some interpretations may assign special meanings to the symbols in a particular namespace, which we will call a reserved vocabulary." -- http://www.w3.org/TR/2002/WD-rdf-mt-20020429/#urisandlit > > [...] > > > onProperty/hasClass: > > if <?r, ?p> is in IEXT(I(ont:onProperty)) > > and <?r, ?a> is in IEXT(I(ont:hasClass)), > > then the set > > { ?o: for some ?s in ICEXT(?r), <?s, ?o> is in IEXT(?p) > > and ?o is in ICEXT(?a) } > > has at least one element. > > Completely wrong. Oops; I must have misread the DAML+OIL model theory... > Something like > then ICEXT(?r) = { ?o : exists ?x in ICEXT(?a) st <?o,?x> in IEXT(?p) } > is needed here. Similarly for other restrictions. OK... > > imports: > > none. imports doesn't constrain interpretations > > (other than having the subproperty relationship > > with rdfs:seeAlso). > > Don't think so. imports means that the OWL KB pointed to should be > considered to be part of this KB. > > A treatment of imports would be something like > > if <?KB1,?KB2> in IEXT(owl:imports) > then the models of ?KB1 are a subset of the models of ?KB2. Hmm... not sure the domain and rangeof imports are KBs... I think of them as documents. This issue is on our list; I don't think I'll try to address it in this proposal. http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.6-daml:imports-as-magic-syntax > No particularly standard-first-order, however. > > [...] > > > > conversely, > > > > if <?a, ?b> is in IEXT(I(ont:intersectionOf1)) > > and <?a, ?c> is in IEXT(I(ont:intersectionOf2)) > > and ?x is in ICEXT(?a). > > then ?x is in ICEXT(?b) and in ICEXT(?c) > > What if happens if there is another ont:intersectionOf1 link from ?a? Well, whatever follows follows. It's probably easy to state inconsistencies. But I don't see this as a problem. > [...] > > > oneOf1/oneOf2: > > > > if <?a, ?b> is in IEXT(I(ont:oneOf1)) > > and <?a, ?c> is in IEXT(I(ont:oneOf2)) > > then ?b is in ICEXT(?a) > > and ICEXT(?c) is a subset of ICEXT(?a). > > > > conversely, > > if <?a, ?b> is in IEXT(I(ont:oneOf1)) > > and <?a, ?c> is in IEXT(I(ont:oneOf2)) > > and ?x is in ICEXT(?a) > > then either ?x = ?b or ?x is in ICEXT(?c). > > Hmm. How does a oneOf finish? > > Suppose we have > IEXT(I(ont:oneOf1)) = { <x,a> } > IEXT(I(ont:oneOf2)) = { } > Then what is the class extension of x? It's not constrained; the if... part of the semantic constraint above is not satisfied. > Suppose we have > IEXT(I(ont:oneOf1)) = { <x,a> } > IEXT(I(ont:oneOf2)) = { <x,x> } > Then what is the class extension of x? It contains at least a; it's otherwise not constrained. > [...] > > And, of course, there are no comprehension constraints, so > > x rdf:type _:y . > _:y one:intersectionOf1 a . > _:y one:intersectionOf2 b . > > does not entail that > > x rdf:type _:z . > _:z one:intersectionOf1 b . > _:z one:intersectionOf2 a . Yes, that's by design. This is my position on... http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.10-DAML-OIL-semantics-is-too-weak as I said earlier... # DDTF/layering: weak class theory seems good enough (5.3, 5.10) Dan Connolly (Tue, May 28 2002) http://www.w3.org/2001/sw/WebOnt/webont-issues.html#I5.6-daml:imports-as-magic-syntax > So, in sum, lots of problems. I see just one, for which thanks for the fix. I'll see if I can spin another draft presently... -- Dan Connolly, W3C http://www.w3.org/People/Connolly/Received on Thursday, 20 June 2002 11:55:03 GMT

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