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Re: Comments on last-call SPARQL draft 20050721, section 2

From: Graham Klyne <GK@ninebynine.org>
Date: Mon, 12 Sep 2005 15:52:40 +0100
Message-ID: <43259638.2070405@ninebynine.org>
To: Bijan Parsia <bparsia@isr.umd.edu>
CC: andy.seaborne@hp.com, public-rdf-dawg-comments@w3.org

Bijan Parsia wrote:
>>> Section 2.3
>>> Concerning the reference to literals-as-subjects.  Is this still an  
>>> option for the Semantic Web family?  I understand that OWL (or  
>>> OWL-DL) requires that subjects be URIs.  Maybe not a problem, but I  
>>> thought I'd mention it.
>> Not editorial.
>> Comments?
> RDF through OWL syntactically forbids literals-as-subjects. However,  
> OWL Full allows for equality relations between data values and abstract  
> individuals. So, semantically, there is already a sense in which the  
> OWL Family allows for literal subjects.
> Furthermore, there a smooth path to OWL-DL with subjects as  
> literals...first order logic certainly allows for the first place of  
> two place predicates to have data values (when it admits such values at  
> all) and OWL-DL is a proper subset of FOL. It could be that certain  
> extensions to literal subjects would be undecidable, but so's SWRL for  
> example. I would expect that a forml of AL-Log would allow for literal  
> subjects and robust decidability.
> In fact, if you were careful about equalities and class membership, it  
> might be a reasonable addition to regular OWL-DL.
> Hope this helps.

Yes, thanks for clarifying.  I thought it might come out as something 
like this, but it's good to have an OWL expert confirm this.


Graham Klyne
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Received on Tuesday, 13 September 2005 07:43:05 UTC

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