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Re: [RDF+OWL] Way of connecting RDF and RIF lists

From: Dave Reynolds <der@hplb.hpl.hp.com>
Date: Fri, 01 May 2009 10:36:14 +0100
Message-ID: <49FAC28E.8070400@hplb.hpl.hp.com>
To: Jos de Bruijn <debruijn@inf.unibz.it>
CC: Sandro Hawke <sandro@w3.org>, RIF <public-rif-wg@w3.org>
Jos de Bruijn wrote:
> 
> Sandro Hawke wrote:

>> Hmmm.  I'm wondering how far you'd get by just adding rules like this:
>>
>>     forall ?L ?x
>>        if is-list(?L) and count(?L) > 0 
>>        then ?L[rdf:first->get(?L, 0) and
>>             ?L[rdf:rest->sublist(?L, 1)
>>
>>     forall ?L ?x
>>        if is-list(?L) and count(?L) = 0 
>>        then ?L = rdf:nil
>>     
>> but I guess they aren't safe, and "?L = rdf:nil" isn't in Core or PRD,
>> and they're ... rather wasteful.
> 
> Actually, I think they are going to be safe, since there is the is-list
> guard.

? Surely the safety definition requires each variable to be grounded by 
a non-external predicate.  Certainly I don't see how those rules could 
be implemented in a PR system.

Dave
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Received on Friday, 1 May 2009 09:37:14 GMT

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