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Re: Can RDF say anything about anything?

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Mon, 17 Feb 2003 06:36:21 -0500 (EST)
Message-Id: <20030217.063621.80349248.pfps@research.bell-labs.com>
To: fmanola@mitre.org
Cc: www-rdf-comments@w3.org

From: Frank Manola <fmanola@mitre.org>
Subject: Re: Can RDF say anything about anything?
Date: Thu, 13 Feb 2003 14:38:07 -0500

> Peter--
> 
> Thanks for this comment.  Regarding the situation you bring up, the
> Primer at that point says:
> 
> > These examples also illustrate one of the basic architectural principles 
> > of the Web, which is that anyone should be able say anything they want
> > about existing resources [BERNERS-LEE98]. 
> 
> [BTW:  If nothing else, you've enabled me to spot a missing "to" in the
> sentence.  Thanks!]
> 
> Specifically, the examples illustrate an independent party commenting on
> a description produced by someone else.  That (roughly) "anyone should
> be able to say anything about anything" is being cited as an
> architectural principle of the Web illustrated by the examples, not as a
> capability of RDF (and certainly not without exceptions).  I frankly
> find it hard to see anyone reading this, and being led to believe that
> they can then make RDF statements that violate RDF/XML (e.g., using
> rdf:ID as a predicate was one of the examples that came up in your
> interaction with Brian).  Of course, being able to "say anything about
> anything" provides the ability to state lies and nonsense (e.g., you
> could say rdf:ID rdf:type ex:MooCow), but we can't really prevent that. 
> Do you see a particular clarification that would help, such as a caveat
> here that there are technical limits to RDF's ability to express things?
> 
> --Frank

Either RDF is able to ``say anything [...] about existing
resources'', in which case the sentence is germane, or it isn't, in which
case the sentence is irrelevant or misleading.  If RDF doesn't satisfy the
principle then there is no reason to keep the allusion.

I find this a general problem with the RDF documents.  A lofty principle is
stated, such as ``say anything ...'' or ``expressing information
... without loss of meaning'', but RDF doesn't even come close to the
principle.

peter



> "Peter F. Patel-Schneider" wrote:
> > 
> > Can RDF say anything about anything?
> > 
> > The RDF documents are contradictory on this point.  The Primer indicates
> > that RDF can be used to let anyone ``say anything they want about existing
> > resources'' with no exception for the resources used by RDF.  Concepts says
> > that ``RDF is an open-world framework that allows anyone to make simple
> > assertions about anything''.  However, Concepts also says that ``Certain
> > URIs are reserved for use by RDF, and may not be used for any purpose not
> > sanctioned the RDF specifications.''
> > 
> > What is the situation here?
> 
> -- 
> Frank Manola                   The MITRE Corporation
> 202 Burlington Road, MS A345   Bedford, MA 01730-1420
> mailto:fmanola@mitre.org       voice: 781-271-8147   FAX: 781-271-8752
Received on Monday, 17 February 2003 06:36:29 GMT

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