- From: Pat Hayes <phayes@ihmc.us>
- Date: Thu, 25 Oct 2007 17:32:16 -0500
- To: "Giorgos Stoilos" <gstoil@image.ece.ntua.gr>
- 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? The question applies to any formalism, but it has been definitively answered for most formal logics in common use. The RDF semantics document answers it for RDF and RDFS, though as Peter notes one has to be careful when interpreting external specifications such as XMLSchema. The reason OWL-Full is different from RDF is that OWL-Full (in fact, OWL) imposes a much larger and more complicated collection of semantic conditions than simple RDF does, so it is more work to demonstrate their internal consistency. Pat >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 >> -- --------------------------------------------------------------------- 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 22:32:34 UTC