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Re: Dataset Semantics

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Mon, 24 Sep 2012 10:44:29 +0200
Message-ID: <50601D6D.5070901@emse.fr>
To: Eric Prud'hommeaux <eric@w3.org>
CC: Pat Hayes <phayes@ihmc.us>, Gregg Kellogg <gregg@greggkellogg.net>, RDF WG <public-rdf-wg@w3.org>
Le 22/09/2012 23:02, Eric Prud'hommeaux a écrit :

<skip/>

>
> I suspect we want to explicitly write this use case off, but, if I write a test for CREATE, it would add a pair<n, emptyRDFgraph>  to a dataset, e.g.
> before:
>    {<s1>  <p1>  <o1>  }
> op:
>    CREATE<foo>
> after:
>    {<s1>  <p1>  <o1>  }<foo>  {  }

FWIW, in the proposal at 
http://www.w3.org/2011/rdf-wg/wiki/TF-Graphs/Minimal-dataset-semantics, 
the "before" is not equivalent to the "after". "after" entails "before", 
but not the opposite, as <foo> does not belong to the vocabulary of 
"before".

What the semantics says informally is:

  <foo> { }

means that there is a graph associated with <foo>.

>
> The before and after states are identical by the semantics you describe. That's probably not a big deal because not all implementations are expected to discriminate empty graphs from non-existent ones; the WG doesn't provide any tests like the one above.

<skip/>
-- 
Antoine Zimmermann
ISCOD / LSTI - Institut Henri Fayol
École Nationale Supérieure des Mines de Saint-Étienne
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France
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Received on Monday, 24 September 2012 08:44:56 GMT

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