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Re: Reification - whats best practice?

From: Dan Brickley <danbri@w3.org>
Date: Wed, 25 Aug 2004 12:48:07 -0400
To: Sandro Hawke <sandro@w3.org>
Cc: Bob MacGregor <macgregor@isi.edu>, Leo Sauermann <leo@gnowsis.com>, 'RDF interesting groupe' <www-rdf-interest@w3.org>
Message-ID: <20040825164807.GJ20056@homer.w3.org>

* Sandro Hawke <sandro@w3.org> [2004-08-25 12:37-0400]
> 
> 
> > The right solution is to use contexts.  Contexts can be implemented
> > using quads instead of triples, or by using a scheme for
> > encapsulating groups of statements, as is done in the Triple system.
> > The DAWG committee is taking baby steps towards contexts by
> > including a SOURCE element in BRQL.  If you substitute the term
> > "context" for "source" in a BRQL query, then you have quads.  Some
> > of us are planning to "abuse" BRQL by treating the sources as if
> > they are contexts.  I would not be surprised if members of the DAWG
> > committee have that in mind (but I can't speak for them).
> > 
> > At some point in the future, quad stores are likely to become
> > commonplace--there are a few already.
> 
> While I'm fond of quad stores (eg in cwm and SWI prolog) and
> agree they're generally the way to go -- how do you propose exchanging
> quad-store data?   My store knows that source x said {a b c}, but how
> do I publish that fact?

This only covers a subset of usage scenarios, but works for me:

In my published RDF files, I just assert things about the RDF/XML
serialized document. Eg. that I'm its dc:creator or foaf:maker. I also
like using a wot:assurance property to relate it to the output of the 
PGP/GPG signing process.

This is a bit of a hack, but in the noble tradition of adding a layer of
indirection to solve a problem. Instead of talking directly about
triples or a graph, you talk about (using whatever RDF vocab you find
appropriate) a document that has that stuff written in it.

Rather than doc.rdf encoding "Sandro makes the claim that 'the sky is falling 
in'", have doc.rdf be "Sandro made skyisfallingin.rdf". Of course context-tagging 
tools are going to be useful in dealing with such data, but I think it
avoids some of ugliness of RDF's regrettable reification vocabulary.

Edd's FOAFBot showed that this approach was deployable (on top of a
context-happy store, Redland). I suspect the existence of RDF
reification has distracted people from simpler approaches like this.
Also the other formalisms around RDF, notably the DL work, isn't happy
with having to reason about claims like this. But then I don't use DLs
so don't really care much there...

Dan
useful 
Received on Wednesday, 25 August 2004 16:48:08 UTC

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