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Re: Intersection of properties?

From: Rinke Hoekstra <hoekstra@uva.nl>
Date: Tue, 5 Aug 2008 08:48:14 +0200
Cc: Michael Schneider <schneid@fzi.de>, Jeff Thompson <jeff@thefirst.org>, public-owl-dev@w3.org, Bijan Parsia <bparsia@cs.man.ac.uk>
Message-Id: <64D29691-C633-489A-9F80-DC0E1705FF30@uva.nl>
To: Pavel Klinov <pklinov@cs.man.ac.uk>


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.


> 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

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