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Re: ISSUE-55 (owl:class): owl:class v. rdfs:class

From: Jim Hendler <hendler@cs.rpi.edu>
Date: Tue, 13 Nov 2007 16:49:22 +0900
Message-Id: <E044E744-D6F4-4047-922F-7CF882EDA293@cs.rpi.edu>
To: Boris Motik <boris.motik@comlab.ox.ac.uk>
Cc: OWL Working Group WG <public-owl-wg@w3.org>

Let me be clear, I am sugesting we think about the issue with respect  
to what we've now designed with respect to punning and such. If we  
could find a solution it would be phenomenal. If not, we can postpone  
this issue, but at least people will know we didn't solve it, as  
opposed to that we didn't consider it.

Sent from my iPhone

On Nov 13, 2007, at 14:08, "Boris Motik" <boris.motik@comlab.ox.ac.uk>  

> Hello,
> Changing rdfs:Class into owl:Class does significantly affect the  
> formal meaning of an ontology. For example, owl:complementOf
> complements the extension of owl:Class, but not of rdfs:Class. If  
> necessary, I can come up with examples in which satisfiability of
> an ontology changes if you change rdfs:Class to owl:Class.
> I know what people will say: in many practical cases, such corner- 
> case changes in the semantics won't affect the ontology
> significantly. Still, it might be a good idea to keep the definition  
> of the language clean so that we know how exactly to interpret
> an ontology.
> Changing an rdfs:Class to owl:Class is something that can be done by  
> an implementation to "repair" an ontology. However, this is
> then something an implementation may choose to do, and the  
> implementation is then responsible for knowing what it is doing.
> In contrast, putting something like this into the language itself  
> opens a whole can of worms. It would make the definition of the
> semantics difficult, and it would make it establishing the precise  
> relationship between the OWL DL and the OWL Full semantics quite
> difficult, if not impossible.
> We can put something like this into a separate FAQ or "Common  
> Practices" document. I believe it might be quite helpful for tool
> developers.
> Regards,
>    Boris
>> -----Original Message-----
>> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org 
>> ] On Behalf Of OWL Working
>> Group Issue Tracker
>> Sent: 13 November 2007 12:42
>> To: public-owl-wg@w3.org
>> Subject: ISSUE-55 (owl:class): owl:class v. rdfs:class
>> ISSUE-55 (owl:class): owl:class v. rdfs:class
>> http://www.w3.org/2007/OWL/tracker/issues/
>> Raised by: James Hendler
>> On product:
>> At ISWC 07, it has come up in several presentations that a great  
>> many OWL Full ontologies (in RDFS
>> esp) become OWL DL if you just change rdfs:class to owl:class -  
>> while it is acknowledged that this
>> makes a semantic change, many people said they simply just do it in  
>> their tools.
>> Given the improved understanding at this point of things like  
>> punning, the WG might want to revisit
>> this issue and see if there is a technical solution that could be  
>> considered - or at least make a
>> clear and precise statement as to why we are unable to do so and  
>> why this dichotomy must consider to
>> exist (as unfortunate as that is)
Received on Tuesday, 13 November 2007 07:50:01 UTC

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