- From: Michael Schneider <schneid@fzi.de>
- Date: Thu, 20 Dec 2007 09:40:41 +0100
- To: "Alan Ruttenberg" <alanruttenberg@gmail.com>
- Cc: "Owl Dev" <public-owl-dev@w3.org>, <pfps@research.bell-labs.com>
Hi again, Alan! Alan Ruttenberg wrote on Monday, December 10: >Here's my understanding of the situation (if I've got it wrong >somewhere, please correct me). > >On Dec 8, 2007, at 3:20 PM, Michael Schneider wrote: > >> But, AFAICS, this would only become a real problem, if in this >> ontology some class is used as an individual (metamodelling). > >Or if the class has instances that are literals. > >> But in such a case, even after changing rdfs:Class to owl:Class, >> the resulting ontology would still be an OWL-Full ontology: There >> would, for example, be an 'rdf:type' triple with some class being >> at the individual position, or a class with an object or >data property >> attached. > >The type triple is inferred in OWL Full - it doesn't have to be >explicit. > >> The OWL-DL reasoner would refuse to work in such a situation, of >> course. > >Because the triple would sometimes need to be inferred by the >reasoner itself, the DL reasoner can't detect the situation in all >cases. Strictly speaking, it can only detect the case where it >certainly shouldn't work. > >> So it looks to me that this recommendation is safe. > >I would say, no. However it might be ok if the user was warned, or >made an explicit declaration to that effect. Looks like things have changed, because Peter has found a way to make the difference "perceivable": <http://lists.w3.org/Archives/Public/public-owl-wg/2007Dec/0227.html> The trick is to force owl:Thing to be a /finite/ class (in Peter's ontology owl:Thing happens to equal the union of the two defined classes, which are both finite). In OWL-Full owl:Thing is always infinite, while it may be finite in OWL-DL. @Peter: However, please consider Jeremy's ISSUE-73 in this context: <http://www.w3.org/2007/OWL/tracker/issues/73> What I cannot tell is whether this is a show stopper for the "rdfs:Class repair" or not. I wouldn't believe so, but I have to ponder about this further. Btw, I think the task of forcing owl:Thing to be a finite set can be even easier achieved by simply making owl:Thing equivalent to some enumeration class. Cheers, Michael -- Dipl.-Inform. Michael Schneider FZI Forschungszentrum Informatik Karlsruhe Abtl. Information Process Engineering (IPE) Tel : +49-721-9654-726 Fax : +49-721-9654-727 Email: Michael.Schneider@fzi.de Web : http://www.fzi.de/ipe/eng/mitarbeiter.php?id=555 FZI Forschungszentrum Informatik an der Universität Karlsruhe Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe Tel.: +49-721-9654-0, Fax: +49-721-9654-959 Stiftung des bürgerlichen Rechts Az: 14-0563.1 Regierungspräsidium Karlsruhe Vorstand: Rüdiger Dillmann, Michael Flor, Jivka Ovtcharova, Rudi Studer Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus
Received on Thursday, 20 December 2007 08:40:56 UTC