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Re: RIF Core shortened

From: Gary Hallmark <gary.hallmark@oracle.com>
Date: Tue, 18 Nov 2008 13:06:43 -0800
Message-ID: <49232E63.1010106@oracle.com>
To: Christian de Sainte Marie <csma@ilog.fr>
CC: kifer@cs.sunysb.edu, Patrick Albert <palbert@ilog.fr>, Dave Reynolds <der@hplb.hpl.hp.com>, "Boley, Harold" <Harold.Boley@nrc-cnrc.gc.ca>, Adrian Paschke <Adrian.Paschke@gmx.de>, Axel Polleres <axel.polleres@deri.org>, RIF WG <public-rif-wg@w3.org>

The effect of importing an XML document, an RDF graph, an OWL ontology, 
or another RIF document is to internalize some axioms, in effect to 
translate them to RIF.  Therefore, one must be able to express those 
axioms in RIF.  Those axioms include naturally the ATOMIC syntactic 
class, excluding equality.  I don't see how it is possible to translate 
an imported element to, say, membership but have no way to assert 
membership. 

Maybe the confusion is about importing vs. External predicates, frames, 
etc.  Import actually internally defines what it imports.  External 
predicates always return the same answer - they are stateless.

Christian de Sainte Marie wrote:
>
> Gary Hallmark wrote:
>
>> I do not know what an "externally defined data model" is.
>
> E.g. an XML Schema (I had your strawman on that subject [1] in mind).
>
> [1] http://lists.w3.org/Archives/Public/public-rif-wg/2008Oct/0046.html
>
>> I like the SWC model, where one can import an RDF graph or OWL 
>> ontology.  But the semantics is defined by mapping those imported 
>> things to the RIF data model, i.e. herbrand terms and frames.  I 
>> think a similar approach works for schema-valid XML.  But that may 
>> mean, depending on how one interprets what an external data model is, 
>> that it is precisely the facts of the form o#C where C is imported 
>> from an XML document (is this an external data model?) that is needed.
>
> Yes. I understand that. But the way the semantics is specified in PRD 
> does not require that the XML schema be translated in PRD, not anymore 
> than it is required that the WM be translated in PRD etc. Of course, 
> it requires that the mapping be specified; but not that the facts be 
> actually asserted in PRD (they are pre-existing in the externally 
> defined data model, if you like).
>
> My point is that being able to assert membership facts is not required 
> for that reason.
>
> Now, that does not mean that there are no, other, legitimate reasons 
> to allow the assertion of such fact.
>
> I detailled my analysis of what should be allowed and what not, but 
> this is just my contribution to the discussion...
>
> Cheers,
>
> Christian
>
>
Received on Tuesday, 18 November 2008 21:09:01 GMT

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