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Re: RIF must cover RDF triples as data

From: Dan Connolly <connolly@w3.org>
Date: Tue, 10 Oct 2006 17:04:22 -0500
To: axel@polleres.net
Cc: Christian de Sainte Marie <csma@ilog.fr>, Dave Reynolds <der@hplb.hpl.hp.com>, RIF WG <public-rif-wg@w3.org>
Message-Id: <1160517862.4606.178.camel@dirk>

On Tue, 2006-10-10 at 23:13 +0200, Axel Polleres wrote:
> Dan Connolly wrote:
> > On Tue, 2006-10-10 at 16:53 +0200, Christian de Sainte Marie wrote:
> > [...]
> > 
> >>But I do not understand what using a "holds" predicate would add (I 
> >>guess it is related to the semantics of a RDF triple, but how?).
> > 
> > 
> > It allows semantics of RDFS and some of OWL to be expressed in RIF
> > rules, as I explained in my message of 25 Sep 2006
> > 
> > Re: [RIF] Extensible Design: Horn semantics and syntax... RDF/OWL
> > integration conventions
> > http://lists.w3.org/Archives/Public/public-rif-wg/2006Sep/0073.html
> > 
> > Here's a sketch of an entailment test case.
> > 
> > Premises:
> > 
> > In an RDF/OWL/turtle document:
> >   ex:bob ex:loves ex:cheese.
> >   ex:loves rdfs:subPropertyOf ex:likes.
> > 
> > In a RIF document:
> >   holds(rdfs:subPropertyOf, ?p, ?q) /\ holds(?p, ?s ?o)
> >       => holds(?q, ?s ?o)
> 
> 
> (How) is this different from
> 
> CONSTRUCT {?s ?q ?o}
> WHERE { ?p rdfs:subPropertyOf ?q. ?s ?p ?o }
> 
> ?

No, I don't mean for it to be different at all.
That's exactly the point... by my reading of the current RIF
semantics proposal[1], we need a holds() predicate in order
to match the semantics of SPARQL (and RDFS and OWL Full).

[1] http://www.w3.org/2005/rules/wg/wiki/A.1_Basis%3A_Positive_Conditions
last edited 2006-09-19 16:10:24

> ... I mean, I know that it is different, but my problem is more the 
> following:
> 
> In what *context* is the inferred triple true? What is the context of 
> the body triples what is the context of head triples here?

Hmm... I don't understand this question. I don't see "context"
in [1]. Could you perhaps phrase the question some other way?

> thanks,
> axel

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Tuesday, 10 October 2006 22:04:41 GMT

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