- From: Michael Schneider <schneid@fzi.de>
- Date: Fri, 2 Nov 2007 20:23:14 +0100
- To: "Evren Sirin" <evren@clarkparsia.com>
- Cc: <public-owl-dev@w3.org>, <jjc@hpl.hp.com>, <alanruttenberg@gmail.com>
Hi, Evren! Evren Sirin wrote on November 02, 2007: >Michael, >You are correct in your understanding of punning. It is true that >punning semantics is strictly weaker than OWL-Full semantics and the >inferences you will get will be a subset of OWL Full entailments. But >what is the alternative? Without punning, any ontology where >classes are >used as instances will not be allowed in OWL-DL and rejected by OWL-DL >reasoners. So you have to use an OWL-Full reasoner which means you are >stuck with incompleteness (I'm not aware of any OWL-Full reasoner) and >depending on which OWL-Full reasoner you use incompleteness come from >different parts (e.g. some reasoners doesn't support >owl:sameValuesFrom, >others don't support owl:oneOf, etc.). At least with punning you know >what causes the incompleteness. If metamodelling brings us away from decidability (this is the real problem, right?), then I see two alternatives: (1) Stop hunting for metamodelling capabilities in OWL-1.1-DL. Metamodelling, even in a restricted form, would really be a useful feature, but the community has already learnt to live with the current situation. (2) Add general metamodelling (not necessarily complete OWL-Full support) to OWL-1.1-DL, and remove the requirement for decidability. My personal preference would be to go the (1)-way for OWL-1.1-DL, as a fast, save and conservative solution. And then (later) start thinking about an additional language somewhere in the middle between OWL-1.1-DL and OWL-1.1-Full, which I would call "OWL-UseFull". ;-) This language would have a few additional most-wanted features (like metamodelling), but it does not allow you to build any of those scary (and useless) constructs, which you can actually build in OWL-Full. A caveat would be that decidability could then not be a requirement anymore. But I would not stop thinking about this proposal from the start on. One would have to determine if this brings real problems in /practice/. In fact, there is a lot of useful software around for undecidable problems, without getting into practical problems, as long as this software is used in a meaningful way (parser generators, type checkers for the Haskell language, automatic reasoners for FOL and HOL, computer algebra systems). >I might be wrong but I'm not aware of >anything other than sameAs-equivalentClass (and possibly >equivalentProperty) relation that would cause the punning semantics >incomplete w.r.t OWL-Full semantics. I think this alone already suffices, no need to look for more. :) >I'd be interested in seeing if >there is any other use case where punning semantics does not entail >everything OWL-Full semantics does. > >FWIW, punning has been implemented in Pellet for years and I don't >remember any of our users calling it "confusing" or "useless". That's interesting to hear, I did not know this. But has this also been a feature in Pellet which has been /applied/ by /many/ users for years? >I believe >it is more of a personal style choice to use punning (it might be >confusing for some people but not others). I think it is a >viable option >for "properties for classes" use case (though I'd personally call it >classes as instances use case) Yes, better. And in fact, the property discussion in my mail was a little bit redundant. Though my intended message was in effect that with punning it is easy to believe that one can assign a property to a class, while one actually assigns it to some equally named, but possibly completely different individual resource. Now, after Alan's answer, I am not certain anymore, if it is still possible that an individual can be different from an equally-named class. This is a core question to me. >because most of these use cases do not >depend on sameAs-equivalentClass relation. I think that this relation is so fundamental, that you cannot really avoid to stumble over it ever and ever again. Perhaps, I will come up with other examples in the future, which demonstrate the /practical/ problems (but not before my headache produced by this topic has gone away again ;-)). > >Cheers, >Evren 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
Received on Friday, 2 November 2007 19:23:36 UTC