- From: Conrad Bock <conrad.bock@nist.gov>
- Date: Thu, 8 Nov 2007 11:16:52 -0500
- To: "'Jim Hendler'" <hendler@cs.rpi.edu>, "'Boris Motik'" <boris.motik@comlab.ox.ac.uk>
- Cc: "'OWL Working Group WG'" <public-owl-wg@w3.org>
Boris, > Let me give you a concrete example. Assume that O1 contains the > following ABox assertion: > (13) hasParent(Bob,Mary) > As long as O2 contains named individuals (Bob, Mary, and so on), you > will get exactly the same answers. Now let O2 be an ontology > containing the following ABox assertion: > (14) hasParent(Bob,_:1) > > Here the difference becomes important. Under the standard "true" > semantics, O2 follows from O1. This is because, in first-order > logic, hasParent(Bob,Mary) entails \exists x : hasParent(Bob,x). So anonymous individuals translate to existentials? I thought anonymnous just meant "has no name". Then O2 would only follow from O1 if sameAs(Mary, _:1). > Under the approximative semantics, O2 *does not* follow from > O1. This is because (14) is actually equivalent to the following > ABox O2': > (14) hasParent(Bob,some-invented-constant) > Now in first-order logic, it is not the case that > hasParent(Bob,Mary) entails hasParent(Bob,some-invented-constant), > so O1 does not entail O2. Though it would if =(Mary, some-invented-constant). Conrad
Received on Thursday, 8 November 2007 16:17:41 UTC