- From: Seaborne, Andy <andy.seaborne@hp.com>
- Date: Fri, 17 Jun 2005 16:36:37 +0100
- To: Olivier Corby <Olivier.Corby@sophia.inria.fr>
- CC: public-rdf-dawg-comments@w3.org
Olivier Corby wrote: > I have a remark concerning the GRAPH statement when there is another > GRAPH within its scope. For example : > > PREFIX foaf: <http://xmlns.com/foaf/0.1/> > SELECT ?src ?bobNick > WHERE > { > GRAPH ?src > { ?x foaf:mbox <mailto:bob@work.example> . > GRAPH ?src2 { > ?x foaf:nick ?bobNick > } > } > } > > One may understand that the internal GRAPH ?src2 can match any named > graph, possibly different from the one that is matched by the outer > GRAPH ?src. > If this is the case, the text in section 8.1 Accessing Graph Labels > at http://www.w3.org/TR/rdf-sparql-query/#accessByLabel is ambiguous : > > "The pattern part of the GRAPH only matched triples in a single named > graph ..." > > The 8.5 Definition for GRAPH is also ambiguous for the same reason. > > > > Best regards, > > Olivier Corby > Oliver, Thanks for noting that. I have cleared it up as part of a change that defines matching a pattern on a dataset. I have removed the text "The pattern part..." and the definition of matching GRAPH has been moved earlier. Andy ==== Definition: RDF Dataset An RDF dataset is a set: { G, (<u1>, G1), (<u2>, G2), . . . (<un>, Gn) } where G and each Gi are graphs, and each <ui> is an IRI. Each <ui> is distinct. G is called the default graph. (<u1>, Gi) are called named graphs. There may be no named graphs. A graph pattern P, where P is not an RDF Dataset Graph Pattern, matches an RDF dataset DS with solution S if P matches G (the default graph of DS) with solution S. ==== Definition: RDF Dataset Graph Pattern If D is a dataset {G, (<u1> G1), ...}, and P is a graph pattern then S is a pattern solution of GRAPH(g, P) if either of: 1. g is an IRI where g = <ui> for some i, and S is pattern solution of P on dataset {Gi, (<u1> G1), ...} 2. g is a variable, S maps the variable g to <ui> and S is a pattern solution of P on {Gi, (<u1> G1), ...}
Received on Friday, 17 June 2005 15:40:44 UTC