- From: Pat Hayes <phayes@ihmc.us>
- Date: Tue, 23 Oct 2007 10:20:37 -0500
- To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
- Cc: jjc@hpl.hp.com, public-owl-dev@w3.org
>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! Pat >peter -- --------------------------------------------------------------------- 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 Tuesday, 23 October 2007 15:21:03 UTC