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Re: why I don't like default graphs in the DATASET proposal

From: Richard Cyganiak <richard@cyganiak.de>
Date: Fri, 30 Sep 2011 11:28:43 +0200
Cc: RDF Working Group WG <public-rdf-wg@w3.org>, public-rdf-dawg-comments@w3.org
Message-Id: <D3D74703-453C-422D-9AB8-A2E64208CD83@cyganiak.de>
To: Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>
Hi pa,

(cc SPARQL comments list)

On 29 Sep 2011, at 16:57, Pierre-Antoine Champin wrote:
> I realize that a statement that I made:
> 
> On 09/29/2011 04:42 PM, Pierre-Antoine Champin wrote:
>> I know that SPARQL does not require that the default graph is *also* 
>> present as a named graph (though it does not forbid it)
> 
> could be argued against by the way SPARQL defines a dataset:
> 
>> An RDF Dataset comprises one graph, the default graph, which does not
>> have a name, and zero or more named graphs, where each named graph is
>> identified by an IRI.

You are right. If taken literally, this definition [1] implies that an RDF Dataset can't have the same triples in the default graph and in a named graph. This clearly isn't the intention, so the wording is a bug in the SPARQL spec and needs to be fixed.

The formal definition [2] is fine.

(RDF graphs are set of triples. If two graphs contain the same triples, they are the same graph  they have no identity beyond the triples they contain.)

Best,
Richard

[1] http://www.w3.org/TR/sparql11-query/#rdfDataset
[2] http://www.w3.org/TR/sparql11-query/#sparqlDataset
Received on Friday, 30 September 2011 09:29:30 GMT

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