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Re: rdf as a base for other languages

From: Jonathan Borden <jborden@mediaone.net>
Date: Mon, 4 Jun 2001 07:26:03 -0400
Message-ID: <078d01c0ece9$24a6a510$0a2e249b@nemc.org>
To: "Brian McBride" <bwm@hplb.hpl.hp.com>, "Peter Crowther" <peter.crowther@networkinference.com>
Cc: <www-rdf-logic@w3.org>
Brian McBride wrote:

>
> I'd like to focus on my main question though.  What are the relative
> merits of 'extending' RDF v designing a new language for
> expressing rules which operate on ground facts expressed in RDF.
>

The problem is the term 'ground fact' and the way it is equated with the
simple _presence_ of a triple in RDF. In so doing, RDF uses up what a _fact_
is. For example, a new language or an extension of RDF might wish to equate
a fact with an expression constructed of multiple triples e.g. a subgraph.
But RDF does not allow the assertion of a subgraph without asserting every
triple in the subgraph.
Hence what should be a simple construct:

(not (color sky blue))

becomes contorted. And this is for a simple expression. More complex
expressions become hopelessely contorted.

If RDF did not direct that a triple is and is always a fact, then other
languages with use RDF would be free to define what are and are not facts.

Jonathan Borden
The Open Healthcare Group
http://www.openhealth.org
Received on Monday, 4 June 2001 07:43:14 GMT

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