- From: Giorgos Stoilos <gstoil@image.ece.ntua.gr>
- Date: Thu, 25 Oct 2007 10:15:54 +0300
- To: "'Pat Hayes'" <phayes@ihmc.us>, "'Michael Schneider'" <schneid@fzi.de>
- Cc: <public-owl-dev@w3.org>, "'Peter F. Patel-Schneider'" <pfps@research.bell-labs.com>, <jjc@hpl.hp.com>
Hi all, Does this question/discussion apply also to RDF or only to OWL Full. If so why is there a difference? Best, Giorgos > -----Original Message----- > From: public-owl-dev-request@w3.org [mailto:public-owl-dev-request@w3.org] > On Behalf Of Pat Hayes > Sent: Wednesday, October 24, 2007 1:26 AM > To: Michael Schneider > Cc: public-owl-dev@w3.org; Peter F. Patel-Schneider; jjc@hpl.hp.com > Subject: RE: Some basic questions about OWL-Full > > > >Pat Hayes wrote: > > > >>>From: Pat Hayes <phayes@ihmc.us> > >>>Subject: Re: Some basic questions about OWL-Full > >>>Date: Tue, 23 Oct 2007 08:58:28 -0500 > >>> > >>>> > >>>> >Peter F. Patel-Schneider wrote: > >>>> >> > >>>> >>For homework: Is EquivalentProperties(owl:sameAs > >>owl:differentFrom) > >>>> >> itself inconsisten? > >>>> >> > >>>> > > >>>> >I'm afraid I'm several years' late on my (easier) homework of: > >>>> > Is (*empty*) itself inconsistent? > >>>> > >>>> Yes, in RDF (and conventional FOL). This is the > >>>> only assumption of Tarskian semantic theory, that > >>>> there is something in the universe. One can build > >>>> a 'free' logic which allows an empty universe, > >>>> but then its proof theory can't have the usual > >>>> rules of instantiation and generalization, which > >>>> allow the inferences > >>>> > >>>> (forall (x) (foo x)) |== (foo A) for some > >>>> 'new' name A |== (exists (x)(foo x)) > >>>> > >>>> Pat > >>> > >>>I think Jeremy meant an empty KB, i.e., whether OWL Full is trivial or > >>>not. > >> > >>Ah, I see. Sorry. Yes, that question amounts to > >>whether the OWL semantic conditions are > >>internally consistent when transcribed into > >>common logic (or FOL using the holds/app style). > >>Good question! > > > >Hm, seems to me that I did not understand neither Jeremy, nor Peter, nor > >you. :) What is meant by "whether OWL Full is trivial or not"? > > "Trivial" in this context means that there would > be no OWL-Full interpretations which satisfy > anything, so everything would be OWL-Full > unsatisfiable. Put another way, the OWL-Full > semantic conditions would be internally > contradictory. > > > Is this the > >question about whether empty OWL-Full ontologies are inconsistent or not? > > That is another way to put it, yes. > > >I.e. whether an empty OWL-Full ontology entails contradictory statements? > > And that is another, yes. > > >But if I have some arbitrary non-empty ontology O := {A1,...,An}, then O > >contains the empty ontology as a sub-ontology. So I would assume that > every > >statement which is entailed by the empty OWL-Full ontology will also be > >entailed by O itself. And if the empty OWL-Full ontology would entail > >contradictory statements, then /every/ OWL-Full ontology would entail > >contradictory statements, and then OWL-Full semantics would be totaly > >broken! > > Quite. Which is what Peter meant by "trivial". I > am confident that this is not the case, but even > if it were I would say they would indeed be > broken, but because in that case the OWL semantic > conditions were themselves broken. And not > necessarily totally, since the next task would be > to see how to weaken them so that they weren't > broken. IMO they are too strong in some ways in > any case, e.g. the intensional view of classes > seems better than the extensional one, c.f. > terHorst's version of OWL. > > >Is it this what you (Pat) mean by "whether the OWL semantic > >conditions are internally consistent..."? > > Yes. > > Pat > > > > >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 > > > -- > --------------------------------------------------------------------- > IHMC (850)434 8903 or (650)494 3973 home > 40 South Alcaniz St. (850)202 4416 office > Pensacola (850)202 4440 fax > FL 32502 (850)291 0667 cell > phayesAT-SIGNihmc.us http://www.ihmc.us/users/phayes >
Received on Thursday, 25 October 2007 07:19:02 UTC