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Re: RDFCore WG: Datatyping documents

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Mon, 04 Feb 2002 12:53:10 -0500
To: patrick.stickler@nokia.com
Cc: D.M.Steer@lse.ac.uk, www-rdf-logic@w3.org
Message-Id: <20020204125310O.pfps@research.bell-labs.com>
From: Patrick Stickler <patrick.stickler@nokia.com>
Subject: Re: RDFCore WG: Datatyping documents
Date: Mon, 04 Feb 2002 19:26:35 +0200

> On 2002-02-04 17:52, "ext Damian Steer" <D.M.Steer@lse.ac.uk> wrote:
> > TDL's method, which doesn't require those clauses, appears much more
> > troublesome. <"0.0",0> != <"0",0> is a typical problem.
> This is a problem with all datatyping proposals that RDF could
> consider, since RDF cannot escape non-canonical lexical forms
> and thus more than one lexical form can denote the same value
> in for a given datatype.
> > This is hardly an original thought (it was discussed on Friday), but
> > could somebody explain why TDL does this? I can see hope for the
> > 'almost a function' approach, but not for the lexical-value pairs.
> Well, not to disparage Jeremy's efforts at providing an MT for
> TDL (which I am not capable of doing and for which I am very
> very grateful to Jeremy for his contributions), the particular approach
> he took, that of the lexical-value pairing, is not exactly the
> same as the basic concept behind TDL, which is more I think
> along the lines of your 'almost a function' approach, and pairs
> the lexical form (literal) with the URI of the datatype as
> a basis for interpretation rather than a lexical form and a
> value.

The problem mentioned above has everything to do with the denotation of
Unicode nodes, and nothing to do with lexical forms.  There are many ways
of getting around it in RDF.

I don't think that you can claim that the TDL model theory is where the
mistake is.   All that this part of the formal TDL model theory is
reflecting is the wordings

	... a datatype class corresponds to its map, a set of pairs of
	lexical strings and their corresponding values.

	An interpretation maps each Unicode node to some literal-value

As long as that wording is in the TDL document, and is reflected in the
formal model theory then it *IS* TDL.  The example pictures cannot override
these ``facts on the ground''. 

And yes, if anyone is counting, I view this as a fatal flaw in TDL.
When I say 

	age rdfs:range xsd:integer .
	John age "10" .

(the XML Schema extension of) the RDF model theory had [...] better have a
denotation of age relationship between the denotation of John and the
integer 10 in *every* model for these two triples.  Anything else is just
plain wrong.

> Cheers,
> Patrick

Peter F. Patel-Schneider
Bell Labs Research
Received on Monday, 4 February 2002 12:53:50 UTC

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