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Re: B-scopes

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Wed, 14 Nov 2012 11:32:21 +0000
Message-ID: <50A38145.4040906@epimorphics.com>
To: public-rdf-wg@w3.org

On 14/11/12 11:02, Richard Cyganiak wrote:
> Following recent discussions, I've written up a proposal to change the design of blank nodes in RDF by explicitly introducing scoped blank node identifiers into the abstract syntax.
> http://www.w3.org/2011/rdf-wg/wiki/User:Rcygania2/B-Scopes
> Requirements:
>  Consistency with all resolutions the WG has made so far
>  No changes to other specs beyond Concepts and Semantics required
>  No changes to conforming implementations required
> All further details are in the wiki.
> Comments welcome.
> Best,
> Richard

The idea may be OK although adding a new piece of terminology to explain 
other unclear concepts may not achieve what you hope for.


I have no idea what a "blank node scope" is.

There is a widely held misconception in the RDF community that graphs 
cannot share blank nodes. This stems from the fact in practice they 
rarely do and almost never need to,

Any systems that has the default query graph as the union of named 
graphs is sharing bnodes across graphs.

Such systems are not 'rare'.

... sharing ...
but (for the time being) not between graph stores.

The skolemization note makes this confusing.  While not strictly at odds 
with it, the appearance of skolemization suggests global bnodes.

Alternative for consideration:

1/ Make clear that parsing produces a new blank nodes every time for the 
same label.

2/ Talk about "fresh blank node" and not the universal 
not-quite-arbitrary set of blank nodes.

3/ Bnodes are global.

Then the "b-scope" and "bNode = (b-scope, label)" is an implementation 

Received on Wednesday, 14 November 2012 11:33:14 UTC

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