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Re: combination of RDF* and graph-level metadata (named graphs)

From: Olaf Hartig <olaf.hartig@liu.se>
Date: Fri, 30 Aug 2019 15:25:31 +0000
To: "public-rdf-star@w3.org" <public-rdf-star@w3.org>
CC: Dan Brickley <danbri@google.com>
Message-ID: <3227942.GGd37kM7rc@porty3>
Dan,

On fredag 30 augusti 2019 kl. 07:42:22 CEST Dan Brickley wrote:
> On Fri, 30 Aug 2019 at 03:36, Olaf Hartig <olaf.hartig@liu.se> wrote:
> [...]
> > Is your idea to use an RDF* triple to capture something like, e.g., "the
> > graph denoted by IRI ex:mygraph contains the edge/triple (ex:Bob,
> > foaf:knows, ex:Alice)." ?
> 
> Yes, or for that matter, expressing the same thing in property graphs

In that case, sure, if you want, you can do this by means of a single RDF* 
triple as illustrated in the following Turtle* snippet:

ex:mygraph  ex:contains  << ex:Bob foaf:knows ex:Alice >> .


Olaf

 
> > Olaf
> > 
> > -----Original Message-----
> > From: Dan Brickley <danbri@google.com>
> > To: Olaf Hartig <olaf.hartig@liu.se>
> > Cc: "public-rdf-star@w3.org" <public-rdf-star@w3.org>, David Booth <
> > david@dbooth.org>
> > Sent: Fri, 30 Aug 2019 12:05
> > Subject: Re: combination of RDF* and graph-level metadata (named graphs)
> > 
> > Quick thought: we could also potentially use rdf* annotations to attach
> > multiple graph edges to a named graph. That feels slightly less
> > heavyweight
> > than classical named graphs, although maybe the difference is trivial?
> > 
> > Dan
> > 
> > On Fri, 30 Aug 2019, 08:52 Olaf Hartig, <olaf.hartig@liu.se> wrote:
> > > David,
> > > 
> > > On torsdag 29 augusti 2019 kl. 14:14:39 CEST David Booth wrote:
> > > > [...]
> > > > 
> > > > My main concerns:
> > > >   - It must be easy to make statements about an entire graph -- a set
> > 
> > of
> > 
> > > > triples -- rather than one triple at a time.  At present RDF* does not
> > > > allow this, but my understanding is that it could be extended to do
> > > > so.
> > > > IMO this is critically important.
> > > 
> > > I don't see why this would be necessary; I mean, I don't think we need
> > > another
> > > such approach. The approaches that you mention below (named graphs, as a
> > > data
> > > model feature, and the N3 syntax to talk about graphs) already give us
> > 
> > the
> > 
> > > means to make statements about an entire graph. Therefore, in contrast
> > > to
> > > these approaches, RDF* focuses on making statements about individual
> > > triples
> > > (similar to standard RDF reification and edge properties in Property
> > > Graphs).
> > > 
> > > Making statements about entire graphs and making statements about
> > > individual
> > > triples are orthogonal issues. Of course, there are use cases in which
> > > we
> > > want
> > > to be able to do both within the same dataset. To this end, the concept
> > 
> > of
> > 
> > > a
> > > named graph may simply be extended to be a pair consisting of an IRI
> > > (the
> > > graph name) and an RDF* graph (rather than an RDF graph). Then, it is
> > > possible
> > > to use the IRI to make statements about the graph as a whole, and within
> > > the
> > > graph you may have (nested) RDF* triples to make statements about some
> > > particular triple.
> > > 
> > > >   - It should be harmonized with other existing mechanisms, such as
> > > > 
> > > > named graphs and N3's ability to talk about graphs.
> > > 
> > > Does the approach outlined above (named RDF* graphs) address this
> > 
> > concern?
> > 
> > > Olaf
> > > 
> > > > Thanks!
> > > > David Booth


Received on Friday, 30 August 2019 15:25:58 UTC

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