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Re: Disjointness of value spaces

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 31 Oct 2002 16:59:44 +0000
To: Brian McBride <bwm@hplb.hpl.hp.com>
Cc: www-xml-schema-comments@w3.org, Patrick Stickler <patrick.stickler@nokia.com>, Graham Klyne <GK@NineByNine.org>
Message-ID: <f5bbs5a4k8v.fsf@erasmus.inf.ed.ac.uk>

Brian McBride <bwm@hplb.hpl.hp.com> writes:

> The RDFCore WG are putting the finishing touches to a proposal for
> using XML Schema Datatypes in RDF graphs.  We hope to have a WD to
> share with folks soon.


> In doing this, the following question has arisen concerning the value
> spaces of the primitive datatypes.
> Are the value spaces of the primitive datatypes disjoint, i.e. are
> there any cases where a value may be in more than value space.  

Not in the XML Schema REC as published.

> A specific case to consider is:
>    is http://example.org/ in both xsd:string and xsd:anyURI


> noting that RFC 2396 states:
>    [[An identifier is an object that can act as a reference to
>           something that has identity.  In the case of URI, the object is
>           a sequence of characters with a restricted syntax.]]
> Put another way, can we assume that if we have two values, one from
> the value space of one primitive datatype, and the other from the
> value space of a different primitive datatype, then they must be
> different values.


> To the best of my knowledge, the RDFCore WG has no preferred answer to
> this question.  We wish to know the answer to ensure that our
> specification accurately reflects XML Schema datatypes.

We are in fact preparing an erratum to clarify this, as the current
wording is somewhat unclear, and in one respect wrong.

  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
          W3C Fellow 1999--2002, part-time member of W3C Team
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
 [mail really from me _always_ has this .sig -- mail without it is forged spam]
Received on Thursday, 31 October 2002 11:59:54 UTC

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