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Re: datatypes and MT

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Fri, 02 Nov 2001 10:01:18 +0000
Message-Id: <>
To: Pat Hayes <phayes@ai.uwf.edu>
Cc: w3c-rdfcore-wg@w3.org
At 06:31 PM 11/1/01 -0600, Pat Hayes wrote:
>This mapping XD is similar in some ways to an interpretation mapping I, 
>but unlike I, it is assumed that XD is computable (in some way), ie given 
>the uri of a datatyping scheme, the machine can somehow access the actual 
>DTS and DTC mappings associated with that datatyping scheme and apply them.

Do I understand correctly:  XD is (presumed to be) computable under *any* 
interpretation, and independently of the particular interpretation 
used?  Or does it depend on the interpretation to map a datatype-scheme-URI 
to DTS, etc.?

I'm puzzled by the phrase "URI of a datatype scheme";  reading your words, 
it seems to me that it is datatypes (as in lexical -> value mappings) (such 
as xsd:integer, etc), or the *members* of DT, that are denoted by URIs.  I 
think I'm missing something, but the wording suggests that a "datatype 
scheme" covers several datatypes, but later explanations talk about a 
datatype scheme as being about a single datatype:

A datatype is a mapping from a lexical domain (a subset of literals) to a 
range of values (a set). A datatype scheme is a set DT plus a fixed mapping 
DTS from DT to datatypes.


Now, a datatyping of a graph is simply a mapping from the literal nodes of 
the graph to a datatype scheme, ie an assignment of a type to each literal 
node of the graph.


Graham Klyne                    MIMEsweeper Group
Strategic Research              <http://www.mimesweeper.com>
Received on Friday, 2 November 2001 05:58:02 UTC

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