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Re: Turtle version 2006-01-02

From: Tim Berners-Lee <timbl@w3.org>
Date: Fri, 20 Jan 2006 13:33:16 -0500
Message-Id: <0A2743D0-6A78-485C-B3AB-4AB393D549F9@w3.org>
Cc: cwm <public-cwm-talk@w3.org>, Dave Beckett <dave@dajobe.org>, Jeen Broekstra <jeen.broekstra@aduna.biz>, Yosi Scharf <syosi@mit.edu>
To: Arjohn Kampman <arjohn.kampman@aduna.biz>

N3 has blank node identifiers starting with  "_:".

Quoting http://www.w3.org/DesignIssues/Notation3.html

"N3 allows the _: namespace as in NTriples. These identifiers are  
used to identify blank nodes in the graph. These are generalized in  
N3 such that they are used to identify blanknodes in the local  
formula. They are arbitrary temporary names for nodes which are  
existentially quanitified within the current formula (not the whole  
file). They can only be used within a single formula, and not within  
nested formulae."


On Jan 20, 2006, at 9:21, Arjohn Kampman wrote:
> [...]
> While working on an update of our N3 writer, I just remembered that
> there is one fundamental difference between Turtle and N3: Turtle has
> the notion of (document-scoped) blank node identifiers but N3 does not
> (AFAIK). RDF/XML and N-Triples also support blank node identifiers.
> The lack of blank node identifiers makes it much harder to export RDF
> data in N3 format when blank nodes are involved, requiring multiple
> passes over the set of statements. Also, some RDF graphs that are
> expressible in RDF/XML and Turtle might not be expressible in N3. For
> example, is it possible to express that a blank node is a subclass of
> itself?
> Any chance that N3 will get support for blank node identifiers in the
> near future?
> Regards,
> Arjohn
> --
> arjohn.kampman@aduna.biz
> Aduna BV - http://aduna.biz/
> Prinses Julianaplein 14-b, 3817 CS Amersfoort, The Netherlands
> tel. +31-(0)33-4659987
Received on Friday, 20 January 2006 18:33:43 UTC

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