W3C home > Mailing lists > Public > semantic-web@w3.org > September 2006

Re: Inheriting property restrictions

From: Paul Gearon <gearon@ieee.org>
Date: Thu, 7 Sep 2006 00:37:50 -0500
Message-Id: <11FE6AD1-8233-4E95-B691-A0C5FB4E6177@ieee.org>
Cc: semantic-web@w3.org
To: ben syverson <w3@likn.org>


On Sep 6, 2006, at 8:45 PM, ben syverson wrote:

>
> Thanks Paul!
>
> I guess it's as I feared -- multiple property restrictions result  
> in the intersection of the restrictions, rather than the union.
>
> No big deal -- I just have to make this extremely clear to users so  
> they don't create an impossible (or even improbable) intersection  
> of restrictions, thereby preventing them from actually applying  
> useful values to the property.
>
> Maybe this should be clearer in the OWL specs? It doesn't really  
> talk about multiple property restrictions and how they interact...

No, I think the specs are actually OK on this.  After all,  
restrictions are formed through subclassing, and subclassing is  
transitive.  It has a clear mathematical meaning.  Saying anything  
else is redundant.

That said, I believe there is a place for a document which describes  
the consequences of OWL.  There is a lot of misunderstanding (some of  
it mine) about how certain OWL constructs interact, particularly with  
the Open World assumption and non-unique names.  This is  
understandable, given that 99% of the rest of the computing world  
operates in a Closed World assumption (negation as failure), and  
often with unique names.

Collecting a lot of the misunderstandings together, and explaining  
both the correct interpretation and WHY this interpretation is valid  
would be very valuable to people learning OWL.  But it shouldn't be  
in the specs.

Regards,
Paul Gearon
Received on Thursday, 7 September 2006 05:39:08 UTC

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