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Re: [Editorial] "blank nodes do not denote specific resources"

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Thu, 19 Jul 2012 08:51:40 +0200
Message-ID: <5007AE7C.9050801@emse.fr>
To: David Booth <david@dbooth.org>
CC: public-rdf-comments <public-rdf-comments@w3.org>
Le 18/07/2012 20:02, David Booth a écrit :
> http://www.w3.org/TR/rdf11-concepts/#resources-and-statements
> says: "blank nodes do not denote specific resources".  I don't think
> that is quite correct, since a blank node *does* denote a specific
> resource.  It just doesn't give that resource a name that is meaningful
> outside the graph.  I suggest rewording this as "blank nodes do not have
> stable names that can be referenced outside of the graph".

Blank nodes do not have names. They are blank. When you refer to name 
not meaningful outside the graph, you are referring to certain concrete 
syntaxes where bnodes are sometimes identifiable by a local name.
Bnodes do not denote a specific resource indeed:

:me foaf:knows [] .

(I know someone)

"someone" or [] does not denote a specific person. The formal semantics 
is also supporting this: an interpretation maps IRIs and literals to 
resources but does not map bnodes to anything. I can interpret the 
triple above as follows:

:me  is mapped to  myself.
foaf:knows  is mapped to  the acquaintance relationship.

That's all I can interpret in this tiny RDF graph. However, in order to 
satisfy the triple, there must exist a resource that :me knows. My 
interpretation of the triple would be false if I did not know anybody.
Antoine Zimmermann
ISCOD / LSTI - Institut Henri Fayol
École Nationale Supérieure des Mines de Saint-Étienne
158 cours Fauriel
42023 Saint-Étienne Cedex 2
Tél:+33(0)4 77 42 83 36
Fax:+33(0)4 77 42 66 66
Received on Thursday, 19 July 2012 06:52:15 UTC

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