- From: Richard Cyganiak <richard@cyganiak.de>
- Date: Fri, 9 Nov 2012 14:19:34 +0000
- To: Olivier Rossel <olivier.rossel@gmail.com>
- Cc: semantic-web@w3.org
- Message-Id: <BEB9B2D4-B8EB-4504-B573-AF39170885F4@cyganiak.de>
On 9 Nov 2012, at 12:38, Olivier Rossel wrote:
> I have been out of the semantic web for some time, and I would like to know
> the current agreement upon named graphs.
>
> Here are my questions:
> - can a triple belong to several named graphs?
Yes.
> - can the argument of the SPARQL "GRAPH" keyword be *a list* of named graph?
No. It can, however, be a variable, so you can do stuff like this (in SPARQL 1.1):
SELECT * {
VALUES ?graph { <graph1> <graph2> <graph3> }
GRAPH ?graph {
....
}
}
(Not tested.)
> if yes, is this list considered to be the union of all those named graphs?
No, the graph pattern is evaluated against each graph individually.
> - is there a plan to investigate algebra of named graphs, such as :
> (namedGraph1 && !namedGraph2) || namedGraph3?
There is no central place where plans to investigate things are registered :-) So I don't know.
Best,
Richard
>
> Any comment is welcome.
>
> Cheers,
>
> Olivier.
>
Received on Friday, 9 November 2012 14:20:07 UTC