W3C home > Mailing lists > Public > www-rdf-interest@w3.org > August 2004

Re: Reification - whats best practice?

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Thu, 26 Aug 2004 16:51:49 +0100
To: <Patrick.Stickler@nokia.com>
Cc: <chris@bizer.de>, <otto@math.fu-berlin.de>, <Eric.Jain@isb-sib.ch>, <www-rdf-interest@w3.org>
Message-Id: <20040826165149.11af245b@hoth.ilrt.bris.ac.uk>

On Thu, 26 Aug 2004 18:40:15 +0300, <Patrick.Stickler@nokia.com> wrote:

> > From: "Dave Beckett" <dave.beckett@bristol.ac.uk>
...

> > > I noticed that Named Graphs extends RDF in at least two ways:
> > > 1) RDF triple subjects can be literals
> 
> This extension is (while IMO worthy of consideration) not
> part of named graphs, but of TriX, TriG, etc.
> 
> Consideration of literal subjects is disjunct from consideration
> of named graphs.

Yeah, but I did notice it the footnote describing it as a "legacy
constraint".  It is the RDF triple definition we shipped.  Not legacy.

> 
> > > 2) RDF triples are quads (sic)
> 
> No. RDF triples are RDF triples. Graphs are sets of triples.
> Graphs, just as any resource, can be named/denoted by URIs. 
> Statements made about graphs are triples, where the URI denoting
> the graph occurs as the subject.
> 
> In any storage implementation or serialization, however, membership 
> of statements in a given graph can be captured as quads (among other
> possible methods) consisting of graph, subject, predicate, and object.

Yes.  Maybe triples associated with a Named Graph name (URIref).

> 
> Such quads are not "extended triples" insofar as triples are
> defined by the RDF specs. They are simply a data structure
> for expressing triples within the (possibly named) graphs to
> which they belong.
> 
> > > so it's really Named non-RDF Graphs.
> 
> No. As I hope the above clarifies, it is certainly
> named *RDF* graphs.

I apologise.  You are of course, correct.

Dave
Received on Thursday, 26 August 2004 15:53:46 UTC

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