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Re: why I don't like named graph IRIs in the DATASET proposal

From: Sandro Hawke <sandro@w3.org>
Date: Tue, 04 Oct 2011 11:15:48 -0400
To: Richard Cyganiak <richard@cyganiak.de>
Cc: Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>, "public-rdf-wg@w3.org" <public-rdf-wg@w3.org>
Message-ID: <1317741348.9596.117.camel@waldron>
On Tue, 2011-10-04 at 16:08 +0100, Richard Cyganiak wrote:
> On 2 Oct 2011, at 18:06, Pierre-Antoine Champin wrote:
> > As you stress it, RDF does not dictate which IRI should denote which
> > resource (including graphs). I don't think I ever suggested to change that.
> > 
> > However, RDF dictates that each time I use the same IRI (as a node), it
> > denotes the same resource.
> No, it doesn't.
> RDF Semantics is concerned with the interpretation of *individual RDF graphs*.
> As far as RDF Semantics is concerned, the same IRI may identify completely different things in different RDF graphs.
> It is the social contracts and conventions of the web that encourage us to converge on a single unique referent for each IRI. This is orthogonal 
> For example, in this triple:
>    <#me> foaf:homepage <http://richard.cyganiak.de/>.
> we all know what the subject of the encoded statement is. But that's not because of RDF Semantics. As far as RDF Semantics is concerned, <http://richard.cyganiak.de/> denotes a completely arbitrary resource. It's conventions that allow us – and the software we create – to understand that the target is a web page that can be accessed via a browser and so on.
> This mechanism *works*.
> I suggest to treat graph names in exactly the same way. When we assert inside some RDF dataset:
>    <#me> ex:assertsGraph <#graph1>.
> then as far as RDF Semantics is concerned, <#graph1> denotes an arbitrary resource. It's conventions – and the definition of ex:assertsGraph – that allow us, and our software, to understand that this talks about a different graph within the same dataset.
> When you and Pat demand that the denotation of graph names in RDF datasets be fixed to the graph, then you conveniently ignore the fact that RDF Semantics currently doesn't have the power to fix the denotation of *anything* (except the RDF(S) built-ins), and *always* defers to convention for establishing the connection between IRIs and things. RDF works nevertheless. Why should it be any different for graphs?

/me sits back, looking forward to the response to this!

Just to clarify, and kind of as an aside, Richard, in this message, when
you say "graph" in assertGraph, etc, do you mean g-snap or g-box?   I
would have expected you to use the term precisely (meaning g-snap), but
I understood you to be advocating a design where we give URIs to g-boxes
not g-snaps.    So I'm a little confused.

    -- Sandro
Received on Tuesday, 4 October 2011 15:15:57 UTC

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