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Re: Current agreement upon named graphs

From: Richard Cyganiak <richard@cyganiak.de>
Date: Fri, 9 Nov 2012 14:19:34 +0000
Cc: semantic-web@w3.org
Message-Id: <BEB9B2D4-B8EB-4504-B573-AF39170885F4@cyganiak.de>
To: Olivier Rossel <olivier.rossel@gmail.com>
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 GMT

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