- From: Axel Polleres <axel.polleres@deri.org>
- Date: Tue, 4 Oct 2011 07:05:32 +0200
- To: Richard Cyganiak <richard@cyganiak.de>
- Cc: SPARQL Comments <public-rdf-dawg-comments@w3.org>
Hi Richard, (answering here only on the comment to the SPARQL-comments list and thus removed the RDF WG in cc:) > >> 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. I don't see how the wording at [1] would imply disjointness of the named and default graphs. Since a *named graph* is a *pair* of a graph and its name (as indeed made more explicit in [2]), any named graph is per definition different from the default graph or from any other named graph, so I don't think that the wording at [1] is buggy. best regards, Axel On 30 Sep 2011, at 11:28, Richard Cyganiak wrote: > 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 Tuesday, 4 October 2011 05:06:03 UTC