- From: Steve Harris <steve.harris@garlik.com>
- Date: Wed, 28 Mar 2012 12:18:48 +0100
- To: Sandro Hawke <sandro@w3.org>
- Cc: public-rdf-wg <public-rdf-wg@w3.org>
This seems good to me, assuming that the TriG docs below will have their current behaviour in SPARQL systems when imported, i.e. SELECT ?type WHERE { ?g a ?type . GRAPH ?g { <a> <b> <c> } } Will return rdf:Graph. The only reservation I have is relating to systems where (out of the box) the default graph is the Union of the named graphs - this is relatively common. If the TriG also has: <u3> { <u2> a foaf:Person } Then the answer to the above query would be ?type = rdf:Graph, foaf:Person - which is not what was intended. In 4store, for example, you could force the issue by instead asking: SELECT ?type WHERE { GRAPH <default:> { ?g a ?type } GRAPH ?g { <a> <b> <c> } } but that's not standard SPARQL, uses a system specific ugly URI, and is probably semantically dubious. - Steve On 28 Mar 2012, at 03:23, Sandro Hawke wrote: > I've written up design 6 (originally suggested by Andy) in more > detail. I've called in 6.1 since I've change/added a few details that > Andy might not agree with. Eric has started writing up how the use > cases are addressed by this proposal. > > This proposal addresses all 15 of our old open issues concerning graphs. > (I'm sure it will have its own issues, though.) > > The basic idea is to use trig syntax, and to support the different > desired relationships between labels and their graphs via class > information on the labels. In particular, according to this proposal, > in this trig document: > > <u1> { <a> <b> <c> } > > ... we only know that <u1> is some kind of label for the RDF Graph <a> > <b> <c>, like today. However, in his trig document: > > { <u2> a rdf:Graph } > <u2> { <a> <b> <c> } > > we know that <u2> is an rdf:Graph and, what's more, we know that <u2> > actually is the RDF Graph { <a> <b> <c> }. That is, in this case, we > know that URL "u2" is a name we can use in RDF to refer to that g-snap. > > Details are here: http://www.w3.org/2011/rdf-wg/wiki/Graphs_Design_6.1 > > That page includes answers to all the current GRAPHS issues, including > ISSUE-5, ISSUE-14, etc. > > Eric has started going through Why Graphs and adding the examples as > addressed by Proposal 6.1: > http://www.w3.org/2011/rdf-wg/wiki/Why_Graphs_6.1 > > -- Sandro (with Eric nearby) > > -- Steve Harris, CTO Garlik, a part of Experian 1-3 Halford Road, Richmond, TW10 6AW, UK +44 20 8439 8203 http://www.garlik.com/ Registered in England and Wales 535 7233 VAT # 849 0517 11 Registered office: Landmark House, Experian Way, NG2 Business Park, Nottingham, Nottinghamshire, England NG80 1ZZ
Received on Wednesday, 28 March 2012 11:19:11 UTC