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RE: Cutting the Patrician datatype knot

From: Geoff Chappell <geoff@sover.net>
Date: Thu, 22 Nov 2001 08:42:30 -0500
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, <www-rdf-interest@w3.org>
Message-ID: <NFBBJNGEILIMIEFCFDIIAEBFCBAA.geoff@sover.net>


> -----Original Message-----
> From: www-rdf-interest-request@w3.org
> [mailto:www-rdf-interest-request@w3.org]On Behalf Of Peter F.
> Patel-Schneider
> Sent: Wednesday, November 21, 2001 1:34 PM
> To: www-rdf-interest@w3.org
> Cc: joint-committee@daml.org
> Subject: Cutting the Patrician datatype knot
>
>
> Hi:
>
> Here is my Thanksgiving turkey for you all. :-)
>
>
> Suppose one decided that nodes in an RDF graph were one of
> 	1/ URIs
> 	2/ blank nodes
> 	3/ data values
> 	4/ text (untidy)
> and that interpretations mapped
> 	1/ URIs into resources [as before]
> 	2/ blank nodes into ... [as before]
> 	3/ data values into themselves!
> 	4/ text into arbitrary literal values!
>
> Then a datatype scheme for the model theory is quite simple,
>
> 	Let DT be a collection of datatypes.
> 	For d in DT let DTC(d) be a set, the extension of d.
>
> The model theory for datatypes is also quite simple.
>
> 	For d in DT  ICEXT(d) = DTC(d)
> 	For d in DT  ICEXT(rdfs:Literal) >= DTC(d)
>
>
> An RDF/XML serialization of an RDF graph element of the form
> 	< s , p , v > for v a data value
> is of the form
> 	<... s ...>
> 	  ...
> 	  <p xsi:type="du">x</p>
> 	  ...
> 	</...>
> where d is some datatype with URI du
> for which v in DTC(d) and x is a lexical form for v in d.
>
> Thus in the serialization we need access to the lexical-to-value mapping,
> but not in the model theory.

If you're going to put the mapping in the parsing, why not just use
'parseType=' to make clear it's a parser directive?

Maybe you could get then get the best of both worlds -- let the data-aware
parser deal with the lexical side of things (by converting the lexical form
to a canonical representaion of the value). The parser could also generate a
triple specifying the range of the property in question as the classname
specified in 'parseType='. Then things could just behave as per your earlier
proposal but without the possible ambiguities in lexical to value mappings
(as the node label is always understood to be a canonical representation of
the value space of the datatype).

> Peter F. Patel-Schneider
> Bell Labs Research
>

Happy Thanksgiving,

Geoff Chappell
Received on Thursday, 22 November 2001 10:19:10 GMT

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