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Re: ISSUE-3: REPORTED: Lack of anonymous individuals

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Tue, 13 Nov 2007 00:12:49 -0500
Message-Id: <F3A0D7CD-80D6-4B86-8603-9BBF180BF87A@gmail.com>
Cc: "Web Ontology Language (OWL) Working Group WG" <public-owl-wg@w3.org>
To: Ivan Herman <ivan@w3.org>

On Nov 10, 2007, at 4:30 AM, Ivan Herman wrote:

> I do not claim I understand all the technical issues here, but  
> wouldn't
> that have any effect on backward compatibility with OWL1.0?  
> (Although we
> still have to define what that means exactly, of course).

I am assuming that you are referring to my first comment re: use of  
bnodes in the RDF rendering.

If we have backwards compatibility mean that old OWL-DL ontologies  
would be considered valid OWL 1.1 ontologies, then yes, we would have  
to still allow bnodes for this use. But we could specify that these  
nodes could be named, as well, I think.

If by backwards compatibility we mean that OWL 1.1 ontologies that  
did not use any features specific to OWL 1.1 were legal OWL DL  
ontologies, then no, we could not do this.

I didn't mean the comment as a suggestion that we actually do this,  
BTW, just as a test of the theory being proposed that there is no  
effective difference between bnodes and skolems. I'm hoping that  
someone that understands this better (Peter?Jeremy?) could comment on  
whether it would in fact make a difference.


> Ivan
> Alan Ruttenberg wrote:
>> Related to the question of skolems versus existentials, I note  
>> that both
>> the OWL 1.0 and the OWL 1.1 RDF mappings make liberal use of  
>> bnodes. Is
>> there any reason that we couldn't use skolems (which are not bnodes)?
>> -- 
>> It doesn't seem like a good idea to me to *interpret* bnodes as  
>> skolems.
>> Better to assume that we serialize skolems as urn:uuid: as Reto
>> suggested in the email Bijan cites.
>> It seems to me that we could actually support both.
>> Individual(type(owl:Thing)) could be a skolem
>> SomeIndividual(type(owl:Thing)) could be an existential.
>> Suppose we dropped bnodes(old style anonymous individuals) from  
>> OWL-DL,
>> but not OWL-Full, what would be the consequences? We couldn't  
>> generate,
>> within OWL-DL, bnodes. I'm not sure this is a big deal. It means we
>> can't generate idiomatic foaf. It also means that OWL rendered in  
>> turtle
>> gets potentially uglier.
>> We could read bnodes within rdf and interpret them within OWL by  
>> way of
>> the translation to the explicit existential (restriction on property
>> blah blah), as long as there were only trees of bnodes, i.e, as  
>> Bijan notes
>> Can anyone say why doing things this way would be problematic?
>> -Alan
> -- 
> Ivan Herman, W3C Semantic Web Activity Lead
> Home: http://www.w3.org/People/Ivan/
> PGP Key: http://www.ivan-herman.net/pgpkey.html
> FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Tuesday, 13 November 2007 05:13:08 UTC

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