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

RE: Reification - whats best practice?

From: <Patrick.Stickler@nokia.com>
Date: Thu, 26 Aug 2004 18:40:15 +0300
Message-ID: <1E4A0AC134884349A21955574A90A7A50A1C32@trebe051.ntc.nokia.com>
To: <chris@bizer.de>, <dave.beckett@bristol.ac.uk>, <otto@math.fu-berlin.de>
Cc: <Eric.Jain@isb-sib.ch>, <www-rdf-interest@w3.org>

> From: "Dave Beckett" <dave.beckett@bristol.ac.uk>
> > > ... and you can even get them quite easily into RDF/XML, simply by
> > > allowing rdf:about/rdf:ID/rdf:nodeID on the <rdf:RDF> wrapper.
> > > Although there are some good arguments for a completetly different
> > > serialization syntax such as TriX...
> >
> > We thought of that.  But slipping in such a huge change to RDF
> > in an existing syntax wasn't where we ended up.
> >
> > 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.

> > 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.

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.




Patrick Stickler
Nokia, Finland
Received on Thursday, 26 August 2004 15:42:03 UTC

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