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Re: semantics status of RDF(S)

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 05 Apr 2001 19:49:24 -0400
To: aswartz@swartzfam.com
Cc: www-rdf-logic@w3.org
Message-Id: <20010405194924D.pfps@research.bell-labs.com>
From: Aaron Swartz <aswartz@swartzfam.com>
Subject: Re: semantics status of RDF(S)
Date: Thu, 05 Apr 2001 00:31:57 -0500

> Peter F. Patel-Schneider <pfps@research.bell-labs.com> wrote:
> 
> > All four of these triples have the same status as triples like
> >   { loves, john, mary }
> > and clutter up the semantic message of a document.
> 
> Clutter up the semantic message? What is the problem here? You're saying
> something, and we're using triples to say it. The semantic message is clear.
> You are saying something about a statement, but not asserting the statement.
> The meaning of what you are saying is defined as all RDF properties are.
> 
> > Yes, three of these triples use RDF reification predicates and so can, maybe,
> > be ignored by RDF processors who are not interested in reified statements (but
> > it is very dangerous to do so).  However, the first triple uses a predicate
> > that is in no way special to RDF and so I don't see how RDF processors and
> > applications can treat it in any other way than triples like
> 
> No, they wouldn't treat it in any special way. They would merely interpret
> the semantics of your message properly. Since you are asserting a negation,
> you are not asserting the actual triple, so you are OK there. Programs that
> will understand your message will deal with it as needed, those that don't
> will not believe the negated statement, but know that some operation is
> performed upon it, and can use this just as they would a normal triple with
> a property they didn't understand. Where is the issue here? Perhaps an
> example would help.
> 
> -- 
> [ Aaron Swartz | me@aaronsw.com | http://www.aaronsw.com ]

OK, here is an example.  (Probably not a good one, however, which would
require lots more thought.)

Suppose that we want to count the number of assertions that are in an RDF
document.  An encoding of disjunction (certainly) or negation (maybe,
depending on how you count) will inflate this number.  Encodings of the
information contained in Drew's recent postings will end up with wildly
incorrect numbers.

Peter F. Patel-Schneider
Received on Thursday, 5 April 2001 19:50:05 GMT

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