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Re: RDFCore WG: Datatyping documents

From: Patrick Stickler <patrick.stickler@nokia.com>
Date: Mon, 04 Feb 2002 20:18:24 +0200
To: "ext Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
CC: <D.M.Steer@lse.ac.uk>, RDF Logic <www-rdf-logic@w3.org>
Message-ID: <B8849D10.D26B%patrick.stickler@nokia.com>
On 2002-02-04 19:53, "ext Peter F. Patel-Schneider"
<pfps@research.bell-labs.com> wrote:

> 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.
>

I'm not quite sure what you're saying here. Do you mean
that a Unicode node is not a lexical form?
 
> 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
> pair.
>
> 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''.

Forgive me for not being clear. I forget that not all are privy
to the history of the TDL proposal.

That wording is part of the model theory, not part of the
original concept of TDL pairings.

I understand that some folks have examined TDL solely on the basis
of the MT presented, and consider the rest of the verbage to be
just so much hand waving and babbling, but the MT was an attempt
at capturing the idea that the identitity of a datatype provides
the necessariy context for interpreting a given lexical form
and that with only the pair of lexical form (literal) and datatype
identity (URIref) it is possible to derive a single consistent
value in the value space of that datatype -- i.e. that a TDL
pairing has a 1:1 correspondence to a mapping between the lexical
and value space.

I believe that to a great extent the MT provided by Jeremy, and
for which I am aware you provided input, did capture most of
that idea, but not without running into some issues regarding
entailment and compatability with tidy literals (both issues
which, I believe, have been resolved -- though work continues
on improving the MT).

Again, I am very grateful to Jeremy's significant contributions
in providing the MT for TDL and feel that the TDL proposal is a
far better proposal because of it.

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

I'm sorry, what is the fatal flaw?

> 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.

I believe we are in agreement. So I'm not sure what
the key point of this discussion now is.

Patrick

--
               
Patrick Stickler              Phone: +358 50 483 9453
Senior Research Scientist     Fax:   +358 7180 35409
Nokia Research Center         Email: patrick.stickler@nokia.com
Received on Monday, 4 February 2002 13:17:14 GMT

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