W3C home > Mailing lists > Public > www-rdf-logic@w3.org > June 2001

Re: rdf as a base for other languages

From: pat hayes <phayes@ai.uwf.edu>
Date: Wed, 6 Jun 2001 14:15:12 -0500
Message-Id: <v04210142b7442ec06bc7@[205.160.76.219]>
To: Brian McBride <bwm@hplb.hpl.hp.com>
Cc: www-rdf-logic@w3.org
>pat hayes wrote:
>[...]
> > I'm not quite clear on the distinction here. I take it that the idea
> > of 'extending' RDF would be that there is a language RDF# which
> > contains RDF, ie every RDF expression is legal RDF#, and has (almost)
> > the same meaning in RDF# as it has in RDF; but RDF# allows other
> > kinds of expressions as well.
> > The other alternative is a language NEW which allows ground RDF facts
> > as legal expressions with the same meaning that they have in RDF, and
> > has other kinds of expressions as well.
> >
> > Hmm. The only difference seems to be that the parts of RDF that
> > express something other than ground facts might be missing from NEW,
> > but would have to be included in RDF#. The trouble is, there don't
> > seem to be any such other parts of RDF.
>
>I'm trying to understand the design space open to us.  Description Logics
>for example, maintain a separation between what they call the A-box
>(which I think of as ground facts) and the T-box (which I think of as rules).
>
>This suggested to me that it might be possible to use RDF to represent the
>ground facts and a more powerful language to express the rules.

I agree that would be a desirable goal. BTW, the 'A-/T-box' 
terminology was originally used to distinguish assertions from 
definitions (of concept vocabulary) , which isnt quite exactly the 
same as the ground-fact/rule distinction. But this is quibbling; I 
agree that 'bare' RDF can be reasonably seen as binary ground atomic 
assertions, and there is obvious utility in using it in that way. It 
seems clear, however, that many of the users of RDF (including 
several who are members of RDFCore :-) use RDF in other ways which 
are not compatible with this strict binary-existential-conjunctive 
logic interpretation. N3/cwm , Euler, and DAML are all examples. So a 
central question seems to me to be, should we be trying to state the 
relational DB interpretation of RDF very clearly, or should we be 
looking for a way to accomodate these other ways of using RDF, and 
re-state the intended interpretation so as to ratify these uses, to 
make them legitimate?

>I was hoping to shift the discussion onto first identifying the
>design space, and then discussing the relative merits of the various
>solutions open to us.  Some test cases would enable us to compare
>different approaches.

I agree that would be a good way to proceed.

Pat Hayes

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Received on Wednesday, 6 June 2001 15:15:15 GMT

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