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Re: rdf as a base for other languages

From: Graham Klyne <GK@ninebynine.org>
Date: Sat, 02 Jun 2001 05:46:28 +0100
Message-Id: <>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: sandro@w3.org, www-rdf-logic@w3.org
At 01:07 PM 6/1/01 -0400, Peter F. Patel-Schneider wrote:
>From: Sandro Hawke <sandro@w3.org>
>Subject: Re: rdf as a base for other languages
>Date: Fri, 01 Jun 2001 12:22:51 -0500
> > In message <20010601115102E.pfps@research.bell-labs.com> you wrote:
> > > Unfortunately RDF only has triples, so triples end up being used for both
> > > the ground facts and the more-complex information.  RDF has no way of
> > > distinguishing between these differing uses of triples, so any 
> triples that
> > > are used to store the more-complex information are also asserted as facts
> > > by RDF.  Worse, ....
> >
> > The "more-complex information" is stored by being described with ground
> > facts.  What's wrong with that?   Where is the confusion?
> >
> > The only potential for confusion I see is that some people might want
> > to jump from having a triple described (with ground facts) to assuming
> > the described triple is true, but that seems clearly wrong.
>Clearly wrong, but RDF mandates that all triples are in the model.  If you
>believe that the model is a representation of some information, then you
>want these triples to be true.  If you don't believe that the model is a
>representation of some information, then what are you using RDF for?
>For example, suppose that you wanted to represent propositional formulae
>within RDF.  You might do something like:
><rdf:type x OR>
><component x y>
><component x z>
><rdf:type y rdf:Statement>
><rdf:subject y John>
><rdf:predicate y loves>
><rdf:object y Mary>
><rdf:type z rdf:Statement>
><rdf:subject z John>
><rdf:predicate z loves>
><rdf:object z Susan>
><loves Bill Susan>
><rdf:type Bill Person>
><rdf:type John Person>
><rdf:type Susan Person>
><rdf:type Mary Person>
>You understand this collection of RDF triples to mean that Bill loves
>Susan and John loves either Mary or Susan, and that they are all people.

Actually, I don't, because I don't know the semantics associated with data 
type "OR".  Base RDF doesn't allow us to make this kind of statement.  But 
I guess that's your point.

My point:  why cannot the "extra" semantics be attached to a particular 
value -- in this case, "OR"?

>Sure, you can do anything you want outside of RDF.  However, if you want
>RDF to represent anything, you better do all your work within RDF.

Why the insistence on all-or-nothing?  Is there any fundamental reason why 
we cannot start with a language capable of expressing ground facts, and 
extend it in a consistent way (creating a new language, "outside" the 
original) such that the original language for expressing ground facts is 
present as a sub-language?


Graham Klyne
Received on Saturday, 2 June 2001 00:57:53 UTC

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