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RE: Reflexivity and antisymmetry uses cases?

From: Gerd Wagner <wagnerg@tu-cottbus.de>
Date: Wed, 17 Jan 2007 11:28:00 +0100
To: "'Alan Ruttenberg'" <alanruttenberg@gmail.com>, "'Holger Knublauch'" <holger@topquadrant.com>
Cc: <public-owl-dev@w3.org>
Message-ID: <000601c73a22$2aa899a0$19b2a8c0@informatik.tucottbus.de>

> 3) A certain skirting around the issue of how RDF and OWL semantics  
> differ from the usual database view of the world. Domain and Range  
> are a constant source of confusion. Open world assumptions also  
> makes, e.g. cardinality restrictions, not behave the way one would  
> expect them to. I think the choice of open world assumption is well  
> motivated, 

Is it really (in all cases)?

I don't think that there was ever any deliberate design decision
in favor of the "open world assumption" (OWA) versus the CWA in
the making of OWL. The OWA is just in the baggage of classical 
mathematical logic, so if you stick to that formalism, you get 
it for free (without having any chance to reject or weaken it).

> but we do need some ability to do closed-world reasoning  
> such as constraint checking, and from a messaging point of view a  
> more head-on approach to discussing  how and why both OWL and RDF  
> differ from databases.

Database languages, such as SQL, are based on computational
experience and best practices. Their formalizations in
computational logics do not imply the OWA. In fact, they
seem to suggest a controlled co-existence of both the CWA
and the OWA.

In order to help RDF and OWL to be more compatible with
computational best practices (such as the distinction
between facts, rules and constraints), it may be necessary
to abandon/relax its strict classcial logic semantics.

-Gerd

---------------------------------------------
Gerd Wagner
http://oxygen.informatik.tu-cottbus.de/IT
 
Received on Wednesday, 17 January 2007 10:28:10 GMT

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