- From: Dan Connolly <connolly@w3.org>
- Date: Fri, 13 Jan 2006 12:27:09 -0600
- To: Pat Hayes <phayes@ihmc.us>
- Cc: public-rdf-dawg@w3.org
On Fri, 2006-01-13 at 12:01 -0600, Pat Hayes wrote: > >In "major technical: underspecified errors" > >http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2006Jan/0066.html [...] > Why do we want to keep the names attached to the FROM NAMED graphs? > Can a query variable bind to the name of a graph in the dataset? Yes. That's one of the main uses of the GRAPH keyword; here's an example from the spec: [[ SELECT ?mbox ?nick ?ppd WHERE { GRAPH data:aliceFoaf { ?alice foaf:mbox <mailto:alice@work.example> ; foaf:knows ?whom . ?whom foaf:mbox ?mbox ; rdfs:seeAlso ?ppd . ?ppd a foaf:PersonalProfileDocument . } . GRAPH ?ppd { ?w foaf:mbox ?mbox ; foaf:nick ?nick } ]] -- http://www.w3.org/2001/sw/DataAccess/rq23/#restrictInQuery The GRAPH keyword is our solution to the SOURCE issue, on which the WG spent considerable time, and closed despite outstanding objections regarding requirements. http://www.w3.org/2001/sw/DataAccess/issues#SOURCE > If > so, we need to re-write the basic definitions to allow for this. We have discussed a sort of wink-nudge approach to the semantics of GRAPH. We talked about a sort of health-warning, a la We're not exactly sure what the formal semantics of GRAPH are. Use with care. (I'm not sure which teleconference this was in, nor whether it was recorded at the time; no matter; the issue is still open.) I am unable to resist reminding everybody that I advised us not to go here: "DanC argued against taking us out of the scope of positive conjunctive queries against RDF graphs." -- http://www.w3.org/2001/sw/DataAccess/ftf4.html and the issues lists also notes a comment on this from Klyne: "I also feel it would be premature to standardize an approach to multi-graph querying ahead of there being a consensus/standard for something like RDF named graphs." -- http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2005Apr/0010.html > Pat -- Dan Connolly, W3C http://www.w3.org/People/Connolly/ D3C2 887B 0F92 6005 C541 0875 0F91 96DE 6E52 C29E
Received on Friday, 13 January 2006 18:27:24 UTC