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RE: Test cases: source of a triple

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Fri, 3 Sep 2004 11:02:26 +0100
Message-ID: <8D5B24B83C6A2E4B9E7EE5FA82627DC96884@sdcexcea01.emea.cpqcorp.net>
To: "Eric Prud'hommeaux" <eric@w3.org>, "RDF Data Access Working Group" <public-rdf-dawg@w3.org>




-------- Original Message --------
> From: Eric Prud'hommeaux <>
> Date: 2 September 2004 01:00
> 
> On Fri, Aug 27, 2004 at 10:28:40AM +0100, Steve Harris wrote:
> > 
> > On Thu, Aug 26, 2004 at 06:37:58 +0100, Andy Seaborne wrote:
> > > My next example (3) then highlights an interaction of SOURCE and
> > > inference if we attempt to use the natural result from case 2. 
> > > Others advocate that SOURCE reflect the origin graph in the
> > > aggregation.  What if it can arise across the aggregations? Are we
> > > saying that inference *can't* be done in this case?
> > 
> > I havent seen anyone else argue for inferred triples being the the
> > graph of one of the ground triples that lead to the inference. It
> > seems like an odd decision. 
> > 
> > If you place inferred triples in another SOURCE/graph (which seems
> > reasonable to me) then these problems go away.
> 
> 
> I propose that we not worry about where the inferences go -- leave
> that to the various engines.

A different name for the RDFS/OWL closure, and closure of the merged
union,  is fine by me.  We just need to be clear.

> They can associate them with whatever
> URI or bnode they want. Further, they can add a bunch of proof
> properties if they want. Some group can define those properties
> after they've been better explored, just as they could say that
> 
>   SOURCE ?foo (?p ?s ?o)
> really means

?rt rdf:type rdf:Statement .

>   ?rt rdf:predicate ?p.
>   ?rt rdf:subject ?s.
>   ?rt rdf:object ?o.
>   ?rt rdf2:label ?foo.

Having "named containers" (see rdf-interest discussion) is interesting.
Are you proposing that SOURCE exactly equivalent to writing the triple
patterns?

[ Changing to s-p-o order everywhere, using some URIs]

If SOURCE <foo> (?s <p> <o>) matches,
does (?rt rdf2:label <foo>) match on its own?
does (?rt rdf2:label <foo>) match if there is no SOURCE in the query?

I'd hope that if the SOURCE clause is removed, it shouldn't change
whether some triple pattern matches even involing the rdf2:label
vocabulary.

What about:

( ?rt rdf:subject ?s )
( ?rt rdf:predicate <p> )
( ?rt rdf:object <o> )

Does this match even if there is no SOURCE?  If so, seems like we are
requiring always-reification in all query implementations and stores.

We may be able to explain SOURCE in this way but a more direct framework
of named containers might be clearer.

	Andy

> 
> By defining a syntax by which our language gets at this provenance
> data, we get to duck the hard questions of how that provenance data
> projects into the RDF world. Call me a coward, but that seems like
> a good idea to me.
> --
> -eric
> 
> office: +81.466.49.1170 W3C, Keio Research Institute at SFC,
>                         Shonan Fujisawa Campus, Keio University,
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> 
> (eric@w3.org)
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Received on Friday, 3 September 2004 10:02:59 GMT

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