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Re: On the context sensitivity of the QName Schema Datatype

From: Pat Hayes <phayes@ihmc.us>
Date: Fri, 15 Feb 2008 14:56:00 -0600
Message-Id: <p06230903c3dbac283b19@[10.100.0.55]>
To: noah_mendelsohn@us.ibm.com
Cc: connolly@w3.org, www-tag@w3.org
At 3:00 PM -0500 2/15/08, noah_mendelsohn@us.ibm.com wrote:
>Dan,
>
>On yesterday's TAG call, you said (from the draft minutes at [1]):
>
>"QName is inconsistently defined in Schema -- abc:xyz can denote two
>distinct values at two points in a document, which is not consistent with
>the statement that there is a mapping from lexical to value space."
>
>So, I thought I'd look at the specificaitons From the published working
>draft of Schema 1.1 Datatypes [2]:
>
>"[Definition:]  In this specification, a datatype has three properties:
>
>     * A ·value space·, which is a set of values.
>     * A ·lexical space·, which is a set of ·literals· used to denote the
>values.
>     * A small collection of functions, relations, and procedures
>associated with the datatype.  Included are equality and order relations
>on the ·value space·, and a ·lexical mapping·, which is a function on the
>·lexical space· onto the ·value space·.
>
>[...]
>
>For some datatypes, notably QName and NOTATION, the mapping from lexical
>representations to values is context-dependent..."
>
>So, while you (or maybe I) might prefer that the design were different, I
>don't think it's fair to imply that the Recommendation is contradictory.
>It makes quite clear that context-dependent lexical mappings are allowed.

I wasn't on the call, so this may be irrelevant, 
but these datatypes are explicitly deprecated for 
use in RDF for exactly this reason, see
http://www.w3.org/TR/rdf-mt/#DTYPEINTERP

RDF *does* assume a fixed lexical-to-value 
mapping for each datatype, so not all the XSD 
datatypes fit the RDF model.

Just a possibly relevant data point.

Pat

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Received on Friday, 15 February 2008 20:56:18 GMT

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