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Re: New blank node scope proposal

From: David Wood <david@3roundstones.com>
Date: Mon, 21 Jan 2013 10:23:00 -0500
Cc: RDF WG <public-rdf-wg@w3.org>
Message-Id: <2783DB8F-8951-43FA-832D-8A62C3D7B3D3@3roundstones.com>
To: Antoine Zimmermann <antoine.zimmermann@emse.fr>

On Jan 21, 2013, at 09:10, Antoine Zimmermann <antoine.zimmermann@emse.fr> wrote:

> You can find my proposal at:
> 
> http://www.w3.org/2011/rdf-wg/wiki/User:Azimmerm/Blank-node-scope
> 
> I thought about adding some things, making the definition of scope more explicit, but that will do for now to start the discussion. The idea is simply translating Pat's definition of a scope: it is a region in which variables have a certain meaning. In RDF, a "region" is a set of triples. That's what I do, I assign a set of triples to scopes. It leads to definig the concept of concrete graph, which is a set of triples "in a scope", formally a pair (scope,graph) which indicates that, according to that scope, the same blank node in any of the triples in the graph is assumed to indicate the existence of the same thing. The same blank node in a different scope would indicate the existence of a different thing.
> 
> For instance, given a bnode b, consider the two triples:
> 
>  (b, owl:sameAs, 1)
>  (b, owl:sameAs, 2)
> 
> the concrete graph:
> 
> (s1, {(b, owl:sameAs, 1)})
> 
> indicates that there is something that is number one.
> 
> (s2, {(b, owl:sameAs, 2)})
> 
> indicates that there is something that is number two. These two graphs are both tautologically true, in OWL semantics. However,
> 
> (s3, {(b, owl:sameAs, 1),(b, owl:sameAs, 2)})
> 
> indicates the existence of something that is 1 and 2 at the same time, which is necessarily false.


In OWL, yes.  It seems to be perfectly valid in RDF.

It seems to me that a better example for our purposes would avoid making logical claims that are beyond the scope of RDF.

Regards,
Dave
--
http://about.me/david_wood


> 
> I also indicate that the scope of concrete graphs must be determined by the application that consumes the data, although publishers have conventional ways of indicating the scope, e.g., by putting the triples in the same file or in between the curly brackets in TriG syntax. However, several files may have the same scope, e.g., if a single graph is too large to be conveniently published as one file.
> -- 
> Antoine Zimmermann
> ISCOD / LSTI - Institut Henri Fayol
> École Nationale Supérieure des Mines de Saint-Étienne
> 158 cours Fauriel
> 42023 Saint-Étienne Cedex 2
> France
> Tél:+33(0)4 77 42 66 03
> Fax:+33(0)4 77 42 66 66
> http://zimmer.aprilfoolsreview.com/
> 



Received on Monday, 21 January 2013 15:23:31 GMT

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