W3C home > Mailing lists > Public > public-rdf-wg@w3.org > August 2012

Re: shared bnodes

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Fri, 24 Aug 2012 12:15:10 +0100
Message-ID: <5037623E.7090002@epimorphics.com>
To: public-rdf-wg@w3.org


On 24/08/12 11:39, Richard Cyganiak wrote:
> On 24 Aug 2012, at 11:19, Antoine Zimmermann wrote:
>> So, I'm saying that you can just forget about trying to identify
>> equal bnodes across graph, and simply rely on a local identifier in
>> one graph, a local identifier in another graph, and tell with a
>> dedicated mechanism that these two locally identified bnodes are
>> assumed to be the same.
>
> I think I'm +1 to this sentiment.
>
> So far, the only argument in favour of allowing shared bnodes that I
> can recall was to manage inferred triples in a separate graph.

And sub/union graphs in general.

Union graphs for those systems that already make one graph the union of 
all others.  Whether we like it or not, those systems are common, even 
maybe even the majority, and have been for several years.

It is the compromise of the context point-of-view and the 
multiple-graphs point-of-view.  In the context POV,

(this is not advocacy, more like 'history')

>
> This is a valid and compelling use case. But an equally valid use
> case would be to manage all the inferred triples in another
> *dataset*. So, if I can infer some triples from graph g1 in dataset
> DS, then I can just store these triples in a graph named g1 in
> dataset DS_inference.

The use case includes being able to have one "thing" which as both base 
and inferred information in it.

>
> Can datasets share bnodes?
>
> The whole bnode sharing thing brings a lot of complexity with it. In
> a complete graph store management language, I need operations for
> "copy graph with bnodes intact", "copy graph with fresh bnodes", and
> so on. Most users won't understand the difference and it will just
> add to the general sense of bewilderment that surrounds bnodes.
>
> I say let's simplify things for once and disallow bnode sharing
> between graphs. The use case above can still be addressed via skolem
> IRIs.

Shared bnodes are already a feature "out there".

(can't say I ever see the "copy graph with fresh bnodes" arise)

>
> Best, Richard
>

	Andy
Received on Friday, 24 August 2012 11:15:38 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 22:02:06 UTC