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Re: Layering LX (or FOL) on RDF

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Tue, 27 Aug 2002 11:54:55 -0400 (EDT)
Message-Id: <20020827.115455.39013986.pfps@research.bell-labs.com>
To: sandro@w3.org
Cc: www-rdf-interest@w3.org

From: Sandro Hawke <sandro@w3.org>
Subject: Re: Layering LX (or FOL) on RDF 
Date: Tue, 27 Aug 2002 11:43:55 -0400

> > If you forbid self-reference, then it is possible.  If you don't correctly
> > capture FOL entailment, then it is possible.  If you extend the syntax of
> > RDF, then it is possible.  If you don't use RDF semantics for RDF triples,
> > then it is possible.
> > 
> > What it depends on is whether you think any of these violates what a
> > same-syntax semantic extension of RDF is.
> So you agree that forbidding self-reference (in the sense discussed
> earlier in this thread) is enough, but you think that doing so
> violates some essential part of RDF?  

Looking back through the thread I can't find a reference to forbidding
self-referential formulae, except where I state it.  How do you forbid
self-referential statements?

> I've had the impression that the
> RDF Core WG is attached to reification for issues like provenance
> (using RDF to record the sources of RDF information), but I'd be
> rather surprised if they were attached to self-referencing sentences.

Well, how does one forbid self-referencing sentences.  To do so, one would
have to say something like

	_:s rdf:type rdf:Statement .
	_:s rdf:subject _:s .

is not an RDF graph.

> I imagine the only reason they allow them is because (1) it's not a
> problem in their negation-free world, and (2) it's more complicated to
> disallow them.

I would instead say that it is impossible *in RDF* to disallow them.  

> To bring this full circle (this thread started with Sean's document),
> I'm finishing up a modifation to cwm which will let it translate N3 to
> RDF triples using the LX vocabulary.  That will demonstrate that N3,
> while not 1-1 equivalent to RDF, is equivalent to RDF + some
> vocabulary.

This will be a nice trick.  How are you going to get the *entire* meaning
of this vocabulary into RDF (without extending the semantics of RDF)?

>     -- sandro

Received on Tuesday, 27 August 2002 11:55:21 UTC

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