- From: Rinke Hoekstra <hoekstra@uva.nl>
- Date: Tue, 5 Aug 2008 08:48:14 +0200
- To: Pavel Klinov <pklinov@cs.man.ac.uk>
- Cc: Michael Schneider <schneid@fzi.de>, Jeff Thompson <jeff@thefirst.org>, public-owl-dev@w3.org, Bijan Parsia <bparsia@cs.man.ac.uk>
Hi, Quick remark (without diving into the discussion, ... which by all means is really interesting) On 5 aug 2008, at 00:43, Pavel Klinov wrote: > First off, unless UNA is asserted I'd say there's no reason to > believe that the two Washingtons represent the same object. So there > should be no contradiction. To avoid confusion: this is *not* how UNA works in OWL. The no-UNA in OWL states that if two entities do *not* have the same name, they are *not* necessarily different. Asserting UNA will remove this, and will make all entities with different names different. However, if two entities have the same name, they *are* the same: this is true under both the UNA and the no-UNA. BTW I think it perfectly right for a DL (or *any*) reasoner to choke on the Washington example: the class assertion simply is inconsistent and false. There exist no individuals that are both a person and a city. No matter what language you use. What you are looking for is probably something like: Washington subClassOf (City or Human) That is, the inconsistent double class assertion is an intersection, whereas what you are aiming at is a union. -Rinke > > Second, some sort of similar ambiguity can be handled in OWL via > punning. > Third, yes, Michael is correct, Pronto does provide non-monotonic > (i.e. default) reasoning. You're welcome to read my blog posts on > that [1] if you're interested. Michael's example is correct but may > not be the best one here because the statements essentially > represent probabilistic facts about *a single* object (which can > belong to one concept or another, we don't know for sure which one). > But what you're looking for is the representation of two distinct > objects using the same name (unless I misunderstood). > Finally, if you're interested in contradictions, I suggest you take > a look at the Anthony Harper's research [2]. He explains how > conflicting pieces of knowledge can be backed by different arguments > so that users (reasoning engines) can choose one or another during > reasoning. > > [1] http://clarkparsia.com/weblog/category/semweb/probabilistic-reasoning/ > [2] http://www.cs.ucl.ac.uk/staff/a.hunter/research/argumentation.html > > cheers, > pavel > >> >> For the moment, it may or may not be interesting for you to have a >> look at >> Pronto: >> >> <http://pellet.owldl.com/pronto> >> >> This Pellet extension provides probabilistic reasoning. I didn't >> yet find >> the time to look deeper at it, but adapting your example above, I >> guess you >> could express assertions like: >> >> * Washington is a Human with prob = 45% >> * Washington is a City with prob = 75% >> >> Now, the result wouldn't be a real contradiction anymore, but only >> wrong >> with a certain (well defined) degree of probability. >> >> But I'm not sure that this is a valid example for Pronto. Bijan can >> (and >> certainly will! :)) tell you more. >> >> Cheers, >> Michael >> >> -- >> Dipl.-Inform. Michael Schneider >> FZI Forschungszentrum Informatik Karlsruhe >> Abtl. Information Process Engineering (IPE) >> Tel : +49-721-9654-726 >> Fax : +49-721-9654-727 >> Email: Michael.Schneider@fzi.de >> Web : http://www.fzi.de/ipe/eng/mitarbeiter.php?id=555 >> >> FZI Forschungszentrum Informatik an der Universität Karlsruhe >> Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe >> Tel.: +49-721-9654-0, Fax: +49-721-9654-959 >> Stiftung des bürgerlichen Rechts >> Az: 14-0563.1 Regierungspräsidium Karlsruhe >> Vorstand: Rüdiger Dillmann, Michael Flor, Jivka Ovtcharova, Rudi >> Studer >> Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus >> >> >> > ----------------------------------------------- Drs. Rinke Hoekstra Email: hoekstra@uva.nl Skype: rinkehoekstra Phone: +31-20-5253499 Fax: +31-20-5253495 Web: http://www.leibnizcenter.org/users/rinke Leibniz Center for Law, Faculty of Law University of Amsterdam, PO Box 1030 1000 BA Amsterdam, The Netherlands -----------------------------------------------
Received on Tuesday, 5 August 2008 06:48:50 UTC