W3C home > Mailing lists > Public > public-rdf-wg@w3.org > January 2013

New blank node scope proposal

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Mon, 21 Jan 2013 15:10:31 +0100
Message-ID: <50FD4C57.9070706@emse.fr>
To: RDF WG <public-rdf-wg@w3.org>
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.

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 14:11:09 GMT

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