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RE: XML Schema WG comments on RDF documents

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Mon, 28 Apr 2003 13:56:35 +0200
To: "Dave Peterson" <davep@iit.edu>, "Jeremy Carroll" <jjc@hplb.hpl.hp.com>, <w3c-xml-schema-ig@w3.org>
Cc: <www-rdf-comments@w3.org>
Message-ID: <BHEGLCKMOHGLGNOKPGHDEEIECBAA.jjc@hpl.hp.com>


> Thus a union datatype has several "potential" lexical mappings,
> one of which
> becomes "operant" when, either by trial and error (running down
> the ordered
> list of member types) or by fiat (using xsi:type), the operant member
> datatype is found.
>
> The point is that '2' would have to somehow be mapped to 2 or the example
> you give would be broken.  For union datatypes, a character string in
> the lexical space can be the lexical representation of more than one
> value in the union's value space.  Your confusion on this point will
> encourage us to explain it more carefully in the Schema 1.1 writeup.

In other words, for a union datatype, the lexical-to-value mapping is not a
function but a relation?

(You seem to be talking about the union of a number of lexical mapping
functions; this union then ceases to be functional).

In RDF Concepts we say:
[[
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).
]]

The XML Schema WG comment questioned the "including zero", but what I hear
now is that also the "exactly one" is incorrect i.e. for XML Schema
Datatypes we would have:

***
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) one or more
members of the value space.
+ Each member of the value space may be paired with one or more members of
the lexical space (lexical representations for that value).
***

Am I getting it?

Jeremy
Received on Monday, 28 April 2003 07:57:08 GMT

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