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RE: Intersection of properties?

From: Michael Schneider <schneid@fzi.de>
Date: Tue, 5 Aug 2008 00:06:15 +0200
Message-ID: <0EF30CAA69519C4CB91D01481AEA06A0AD91E3@judith.fzi.de>
To: "Jeff Thompson" <jeff@thefirst.org>
Cc: <public-owl-dev@w3.org>, "Bijan Parsia" <bparsia@cs.man.ac.uk>
[cc'ed Bijan for clarification on Pronto]

Jeff Thompson wrote:

>Here is my pressing issue.
>
>The OWL language goes to great lengths to be monotonic and decidable,
>but cannot express what to do with contradictions.  For example:
>DisjointClasses(Human, City)
>ClassAssertion(Washington, Human)
>ClassAssertion(Washington, City)
>
>Contradictions like this are inevitable.  For me to be able to use OWL
>without
>needing to extend it with an external rules language, an OWL ontology
>needs to be expressive
>enough to say what to do if someone inserts a contradictory assertion.
>This is such an obvious "use case" that it may be been talked to death
>already.
>Will some future version of OWL be expressive enough to give a rule for
>resolving
>contradictions?

That's a different notion of "expressiveness" as what I normally associate
with a language such as OWL. OWL is based on classical logic, but what you
are asking for isn't. I don't expect the core language of OWL to follow this
direction in the future. However, OWL might grow into a whole set of related
languages, where some of them are non-classical, who knows... 

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)
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Email: Michael.Schneider@fzi.de
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Received on Monday, 4 August 2008 22:06:54 GMT

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