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Re: RDF-ISSUE-17 (graph merge): How are RDF datasets to be merged? [RDF Graphs]

From: Yves Raimond <Yves.Raimond@bbc.co.uk>
Date: Mon, 28 Mar 2011 17:28:42 +0100
To: Nathan <nathan@webr3.org>
Cc: RDF Working Group WG <public-rdf-wg@w3.org>
Message-ID: <20110328162842.GI20337@dvbstreamer.national.core.bbc.co.uk>
On Mon, Mar 28, 2011 at 05:15:52PM +0100, Nathan wrote:
> would it be needed? if we can union instead of merge, then surely we
> can do intersections, differences and all the rest without a
> problem?

Indeed! Although the RDF Semantics aleady define a method to merge RDF graphs [1], and that doesn't make it trivial to compute differences of graphs... 

To be completely honest, I am not sure the definition there makes it easy to understand 'merges' as well (what does 'blank nodes in common' mean for two graphs?) - but maybe I am just missing something.

Best,
y

[1] http://www.w3.org/TR/rdf-mt/#defgraph

> 
> Yves Raimond wrote:
> >Could we bundle graph diffs in that issue as well?
> >
> >Best,
> >y
> >
> >On Mon, Mar 28, 2011 at 03:07:20PM +0000, RDF Working Group Issue Tracker wrote:
> >>RDF-ISSUE-17 (graph merge): How are RDF datasets to be merged? [RDF Graphs]
> >>
> >>http://www.w3.org/2011/rdf-wg/track/issues/17
> >>
> >>Raised by: David Wood
> >>On product: RDF Graphs
> >>
> >>The "RDF Semantics" spec defines how to merge two or more RDF graphs,
> >>the pain is caused by blank nodes, otherwise it's a trivial operation.
> >>
> >>The "SPARQL Query Language for RDF" spec defines the notion of RDF
> >>dataset as a set of "one graph, the default graph, which does not have
> >>a name, and zero or more named graphs, where each named graph is
> >>identified by an IRI".
> >>
> >>How do we define how to merge RDF datasets?
> >>
> >>One obvious answer is we merge all the default graphs and all the
> >>named graphs with the same IRI using the procedure defined by the "RDF
> >>Semantics" to merge RDF graphs.
> >>
> >>NB: This issue will also relate to the "Cleanup Tasks" product if the RDF Semantics document will need to change in relation to named graphs.
> >>
> >>At Talis, within the Talis Platform, we want to enable people to
> >>easily merge RDF graphs into an RDF dataset and perhaps RDF datasets
> >>into another RDF dataset. We also want to have these merge happen in
> >>real-time (i.e. as you add/remove triples from the graphs you update
> >>all the derived graphs/datasets).
> >>
> >>Thanks to Paolo Castagna of Talis for providing input to this issue.
> >>
> >>
> >>
> >>
> >
> >
> >
> 
Received on Monday, 28 March 2011 16:29:11 UTC

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