- From: Ian Horrocks <horrocks@cs.man.ac.uk>
- Date: Thu, 22 Aug 2002 14:46:28 +0100 (BST)
- To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
- cc: phayes@ai.uwf.edu, <www-webont-wg@w3.org>
I see some other (and to my mind even more fundamental) problems with this proposal, and indeed with the whole "strong layering" idea. In particular, the domain of discourse now necessarily contains various syntactic artifacts that place some lower bound on its cardinality (possibly infinite if we need comprehension). This has a number of strange (and undesirable) effects. E.g., an ontology containing the single axiom "Thing subclassOf (oneOf x)" (i.e., "x is the only object in the world" - a seemingly harmless statement) no longer has any model. Moreover, negation behaves strangely, because the negation of a "normal" class contains all the syntactic "junk". This can again lead to strange inferences regarding the cardinality of classes. Regards, Ian On Wed, 21 Aug 2002, Peter F. Patel-Schneider wrote: > > John rdf:type owl:Thing . > > does not entail > > John rdf:type _:x . > _:x owl:oneOf _:l . > _:l owl:first John . > _:l owl:rest owl:nil . > > > > > -- Ian Horrocks, Department of Computer Science, University of Manchester, Oxford Road, Manchester, M13 9PL, UK. Tel: +44 161 275 6133 Fax: +44 161 275 6211 Email: horrocks@cs.man.ac.uk WWW: http://www.cs.man.ac.uk/~horrocks
Received on Thursday, 22 August 2002 09:42:33 UTC