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Re: Comment on Last Call Working Draft of RDF Semantics document concerning datatypes

From: pat hayes <phayes@ai.uwf.edu>
Date: Sun, 26 Jan 2003 10:00:09 -0700
Message-Id: <p05111b13ba59c2e03abb@[]>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: www-rdf-comments@w3.org, w3c-rdfcore-wg@w3.org

>I believe that there is a missing part of datatypes in the RDF model
>theory, and, moreover, that this missing part makes datatypes unusable
>in RDF.  The missing part is a mechanism for tieing a URI reference to
>a datatype.

The model theory assumes that some urirefs denote datatypes. It does 
not, and I believe should not, specify the mechanism by which such a 
name-value association is created or established or communicated. 
These issues are concerned with the use of urirefs as names, and 
therefore go beyond the remit of the RDF WG, and also beyond the 
theoretical area of model theory, in fact.

I agree that there is an important issue here which needs to be 
addressed by someone, but I do not think it is up to us to deal with 
it. It goes well beyond RDF, and has consequences for all users of 
the SW. It is a job for a TAG group, in my opinion.

>For example, suppose that I want to have a datatype that takes octal
>numerals to the appropriate integer.  According to Section 3.4, I
>create a datatype whose lexical space is octal numerals, those value
>space is the integers, and whose lexical-to-value mapping is the
>appropriate one.  Suppose further that I only want this one datatype.
>I then form the set containing only this datatype (and some other
>domain element for XML Literals).  Let's call my datatype O and the
>datatype for XML Literals X, so I need to form the set { O,X } .

You also need to 'associate' a uriref with your datatype in such a 
way that an RDF engine can access the needed information by using 
your uriref. Exactly how this is to be done I do not know. I do not 
know even how to specify that it should be done. I imagine that some 
set of protocols will be required which will involve an API 
accessible by using the uriref as a URL in the usual way. But these 
matters go outside and beyond the model theory.


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Received on Sunday, 26 January 2003 11:58:51 UTC

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