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RE: xmlsch-04 values without lexical forms

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Mon, 28 Apr 2003 15:20:42 +0200
To: "Brian McBride" <bwm@hplb.hpl.hp.com>, "Jeremy Carroll" <jjc@hplb.hpl.hp.com>, <w3c-rdfcore-wg@w3.org>
Message-ID: <BHEGLCKMOHGLGNOKPGHDMEIFCBAA.jjc@hpl.hp.com>


The comment asks us to reword concepts

[[
A datatype mapping is a set of pairs whose first element belongs to the
lexical space of the datatype, and the second element belongs to the value
space of the datatype:

+ Each member of the lexical space is paired with (maps to) exactly one
member of the value space.
+ Each member of the value space may be paired with any number (including
zero) of members of the lexical space (lexical representations for that
value).

]]

to change "including zero" to "one or more", if we do this then we have to
change the lexical-to-value mapping from being a function which maps a
string to the first value associated with it in an XML Schema union, to
being a relation, which maps a string to any of the values associated with
it. XML Schema provides a mechanism by which the appropriate member of the
set of associated values can be chosen; this mechansim is not open to RDF
datatyping.

I am increasingly inclined to urge rejection of both this comment and the
renaming to use XML Schema's terminology comment on the grounds that we wish
to be able to reuse XML Schema union datatypes without reusing the whole XML
Schema framework.

Jeremy

> -----Original Message-----
> From: Brian McBride [mailto:bwm@hplb.hpl.hp.com]
> Sent: 28 April 2003 15:12
> To: Jeremy Carroll; w3c-rdfcore-wg@w3.org
> Subject: Re: xmlsch-04 values without lexical forms
>
>
> My reading of schema datatypes is that with a union type:
>
>    o a lexical form can be ambiguous - i.e. might map to different values
> depending on which component type is used to do the mapping
>
>    o the component types of a union are ordered by the order they are
> declared when defining the union
>
>    o by default the ambiguity is resolved by applying the first
> type whose
> lex space includes the literal
>
>    o the default can be overridden by using an xsi:type attribute
>
> In RDF we always use the default disambiguation rule.  If you want to
> override, use a more specific datatype in the rdf:datatype attribute.
>
> I guess I'm missing something.
>
> Brian
>
> At 14:17 28/04/2003 +0200, Jeremy Carroll wrote:
>
>
> >I am increasingly worried by
> >
> >http://www.w3.org/2001/sw/RDFCore/20030123-issues/#xmlsch-04
> >
> >see
> >
> >http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2003Apr/0281.html
> >
> >(it does not seem to have made it into www-rdf-comments yet)
> >
> >Jeremy
>
>
Received on Monday, 28 April 2003 09:21:18 EDT

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