- From: Pat Hayes <phayes@ihmc.us>
- Date: Tue, 23 Oct 2007 08:58:28 -0500
- To: Jeremy Carroll <jjc@hpl.hp.com>
- Cc: public-owl-dev@w3.org
>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 > >Jeremy -- --------------------------------------------------------------------- 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 13:58:42 UTC