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Re: Test cases for literal equality?

From: Dave Beckett <dave.beckett@bristol.ac.uk>
Date: Tue, 01 Apr 2003 16:13:44 +0100
To: Dan Connolly <connolly@w3.org>
cc: Graham Klyne <gk@ninebynine.org>, w3c-rdfcore-wg@w3.org
Message-ID: <15329.1049210024@hoth.ilrt.bris.ac.uk>

>>>Dan Connolly said:
> On Thu, 2003-03-13 at 05:32, Dave Beckett wrote:
> > xsd:string is a datatype in the XSD specification and from what I
> > recall, RDF doesn't use it - no RDF literal is an xsd:string nor has
> > one as a part,
> 
> If people are going to continue to say things like this about
> literals in RDF vs. XML Schemas, I guess I'll have to take
> a much stronger position on=20
> http://www.w3.org/2001/sw/RDFCore/20030123-issues/#danc-02
> 
> On the contrary, *every* RDF literal is either an xsd:string
> or has one in part.

The concepts WD does not say this explicitly.

> Proof: "The =B7value space=B7 of string is the set of finite-length
> sequences of characters"
>  -- http://www.w3.org/TR/xmlschema-2/#string
> 
> "A literal in an RDF graph contains three components called:
> 
>       * The lexical form being a Unicode [UNICODE] string in Normal Form
>         C [NFC]."
>  -- http://www.w3.org/TR/rdf-concepts/#section-Literals


And are all XSD strings in Normal Form C?  
  http://www.w3.org/TR/xmlschema-2/#string
doesn't seem to say that.

It's clear what a literal in an RDF graph is from the above
definition.  Although an xsd:string would be capabable of
transporting (encoding?) the lexical form part of RDF literal, there
would would be requirement that it was in NFC.

> 
> >  although the lexical form definition is compatible
> > with it.  A quick grep in the concepts WD confirms this as far
> > as I can tell.  So we don't need to test xsd:string comparisons.
> 
> I think that's a counter-productive direction to take.

If we added such a (normative) dependency on all of RDF to xsd:string
and hence the XML Schema RECs, I worry what that would imply.
  Would all implementors need an "XML schema implementation" of some sort?
  Would the RDF Semantics WD have to deal with the semantics of XSD?

Dave
Received on Tuesday, 1 April 2003 10:15:55 EST

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