- From: Taowei David Wang <tw7@cs.umd.edu>
- Date: Tue, 29 May 2007 10:49:40 -0400 (EDT)
- To: Jeremy Carroll <jjc@hpl.hp.com>
- cc: Ulrike Sattler <sattler@cs.man.ac.uk>, Matt Williams <matthew.williams@cancer.org.uk>, Ian Horrocks <horrocks@cs.man.ac.uk>, Owl Dev <public-owl-dev@w3.org>, Semantic Web <semantic-web@w3.org>, Bijan Parsia <bparsia@cs.man.ac.uk>
> Hmmm, I would like to see a small ontology which is necessarily infinite. As the movie 300 has made the Greek phalanx popular again, here is a small ontology that contains a class that has only infinite models: Guard subclassOf ( (some shields.Guard) and ( <2 inverse(shields)) ) FirstGuard subclassOf ( Guard and ( <1 inverse(shields) ) "Every Guard shields some Guard, and is in turn shielded by at most 1 Guard." "A FirstGuard is a Guard, and is not shielded by another." FirstGuard has no finite model, because it generates an infinite number of Guards (every Guard needs to shield someone, and it can't be the FirstGuard). The above example is found in this paper (Page 4, Sec 3): http://citeseer.ist.psu.edu/calvanese96finite.html other refs on topics of computing finite models in DL: http://citeseer.ist.psu.edu/710125.html http://www.inf.unibz.it/~franconi/dl/course/articles/reasoning-survey.ps.gz I am sure others would chime in with newer papers, but these were helpful to me. Cheers, Dave ---- > I've just being looking with google, and found my own > http://www.w3.org/TR/owl-test/dl-900-arith#description-logic-908 > > which I believe hinges on > 2*3*n = 5*n & n>0 > implies n >= aleph0, > but I am still trying to understand it. > > thanks for a pointer > > Jeremy > > > > -- > Hewlett-Packard Limited > registered Office: Cain Road, Bracknell, Berks RG12 1HN > Registered No: 690597 England > >
Received on Tuesday, 29 May 2007 17:56:15 UTC