- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Tue, 23 Oct 2007 10:15:24 -0400 (EDT)
- To: phayes@ihmc.us
- 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. peter
Received on Tuesday, 23 October 2007 14:25:39 UTC