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Re: what RDF is not (was Re: RDF/XML Syntax Specification (Revised) W3C Working Draft published)

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Fri, 21 Dec 2001 13:37:58 -0500
To: jos.deroo.jd@belgium.agfa.com
Cc: bwm@hplb.hpl.hp.com, mmoran@netphysic.com, dave.beckett@bristol.ac.uk, www-rdf-interest@w3.org
Message-Id: <20011221133758S.pfps@research.bell-labs.com>
From: jos.deroo.jd@belgium.agfa.com
Subject: Re: what RDF is not (was Re: RDF/XML Syntax Specification (Revised) W3C Working Draft published)
Date: Fri, 21 Dec 2001 00:25:33 +0100

[...]

> That is not what I was trying to do, sorry for the confusion.
> I think I took consistent steps along the lines of
> 
> [[
>   The use of the phrase "asserted triple" is a deliberate weasel-worded
>   artifact, to allow an RDF graph or document to contain triples which
>   are being used for some non-assertional purpose. Strict conformity to
>   the RDF 1.0 specification [RDFMS] assumes that all triples in a document
>   are asserted triples, but making the distinction allows RDF parsers and
>   inference engines to conform to the RDF syntax and to respect the RDF
>   model theory without necessarily being fully committed to it. RDF as
>   presently defined provides no syntactic means to distinguish asserted
>   from nonasserted triples, however, so the distinction can be safely
>   ignored in the remainder of the document, which assumes that all triples
>   in a graph are asserted.(To apply the subsequent results to RDF containing
>   unasserted triples, it would be necessary to restrict the definitions to
>   the sets of asserted triples in the graphs.)
> ]] -- http://www.coginst.uwf.edu/users/phayes/w3-rdf-mt-current-draft.html
> 
> and
> 
> [[
>   Notice however that such a variable-binding process would only be
>   appropriate when applied to the conclusion of a proposed entailment.
>   This corresponds to using the document as a goal or a query, in contrast
>   to asserting it, i.e. claiming it to be true. If an RDF document is
>   asserted, then it would be invalid to bind new values to any of its
>   unlabeled nodes, since (by the anonymity lemmas) the resulting graph
>   would not be entailed by the assertion.
> ]] -- http://www.coginst.uwf.edu/users/phayes/w3-rdf-mt-current-draft.html
> 
> and log:implies as/is entailment
> 
> --
> Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/

I don't think that your manipulations are permissable, at least not in
RDF(S).

In particular, entailment is a meta-theoretic notion, and is not part of
the syntax of a logical formalism.  Some logical formalisms can turn some
or all entailments into implication, but not all can.

In any case, I'm still confused as to what you were trying to demonstrate.
Perhaps you were trying to show that RDF(S) is a fragment of first-order
logic.


Peter F. Patel-Schneider
Bell Labs Research
Received on Friday, 21 December 2001 13:39:24 GMT

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