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

From: Jos de Bruijn <debruijn@inf.unibz.it>
Date: Fri, 01 May 2009 11:46:41 +0200
Message-ID: <49FAC501.90508@inf.unibz.it>
To: Dave Reynolds <der@hplb.hpl.hp.com>
CC: Sandro Hawke <sandro@w3.org>, RIF <public-rif-wg@w3.org>


Dave Reynolds wrote:
> 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.

Sorry, yes, you are completely right.


Jos

> 
> Dave

-- 
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Jos de Bruijn,        http://www.debruijn.net/
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Received on Friday, 1 May 2009 09:47:28 GMT

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