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Re: RDF and OWL compatibility

From: Michael Sintek <sintek@dfki.uni-kl.de>
Date: Wed, 04 Jan 2006 20:35:50 +0100
Message-ID: <43BC2396.2010801@dfki.uni-kl.de>
To: public-rif-wg@w3.org

Jos de Bruijn wrote:
> On Tue, 2006-01-03 at 18:21 +0000, Dave Reynolds wrote:
>>Michael Sintek wrote:
>>I agree that RDF compatibility requires support for quantification over RDF 
>>properties. Whether this translates into a requirement for a higher-order 
>>syntax for the rule language or into a requirement that the RDF mapping 
>>should use some more straightforward "triple(s,p,o)" convention is a 
>>separate decision.
> I'm not sure whether support for quantification over RDF properties is
> required, but I can imagine it could be.

The query <s,?p,o> was only one example where higher order would be
needed for the "straightforward" mapping. The same problem arises for
queries of the form <s,rdf:type,?c> (i.e., asking for all classes
of a given instance). If you map triples of the form
<s,rdf:type,c> to c(s), you again need higher order.

Additional examples can be constructed with
rdfs:subClassOf and rdfs:subPropertyOf.

The whole problem is somehow related to supporting T-box vs.
A-box reasoning: for the straightforward mapping, Horn logic
supports A-box reasoning, but not (much of) T-box reasoning.

> I think the syntax "triple(s,p,o)" would in this case be the more
> feasible, since we decided to stay syntactically in function-free Horn
> (with rule safety) for phase 1. 

Hmmm, the minutes of the Dec 20 telecon say:

   "digression clarified that phase 1 is full horn, not function-free


Michael Sintek -- DFKI GmbH, Kaiserslautern
http://www.michael-sintek.de -- sintek@dfki.uni-kl.de
phone: +49 631 205-3460 -- fax: +49 631 205-4910
Received on Wednesday, 4 January 2006 19:35:16 UTC

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