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Re: Denotation of XMLLiterals: poll

From: Jan Grant <Jan.Grant@bristol.ac.uk>
Date: Wed, 6 Aug 2003 12:50:23 +0100 (BST)
To: Brian McBride <bwm@hplb.hpl.hp.com>
cc: rdf core <w3c-rdfcore-wg@w3.org>
Message-ID: <Pine.GSO.4.44.0308061245010.15854-100000@mail.ilrt.bris.ac.uk>

On Wed, 6 Aug 2003, Brian McBride wrote:

>
> It seems that there is some concern about XMLLiterals denoting octet
> sequences.  As I understand things, RDFCore doesn't feel strongly that
> the denotation MUST be octet sequences.  Pat has layed what we really
> care about in:
>
> http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2003Jul/0452.html
>
> I suggest we accept Pat's suggestion and reconsider the denotation of
> XMLLiterals.  I have seen three suggestions, as I recall:
>
>   A) be a bit vague about XMLLiterals really are - just define their
> essential properties
>
>   B) have them denote XPATH nodesets
>
>   C) have them denote a pair (uri, lex form), where uri is the uri of
> rdf:XMLLiteral.
>
> Concern has been expressed about A being to vague.  Others have
> responded saying thats normal - integers are defined in terms of their
> properties.
>
> Concern has been expressed that XPATH nodesets are too vague, we don't
> really know that they are and are thus no better than A, but are in some
> way worse.  Cannonicalization does define an equality relation on them
>
> I have heard a private concern expressed about C, that if we did that,
> shouldn't we treat all datatypes that way.  Further, that this does
> guarantee that there are no other ways of denoting the same pair with
> another, posibly user defined datatype.

I think that's a con, not a pro. Currently we have one datatype for
XMLLiteral; preserving the ability to produce subtypes is important.

> How do we choose?  If you have a preference and rationale, it would be
> good hear it.

What Pat said: clearly XMLLiterlas can be lots of different things to
different people. I don't think Pat's idea was "vague". Basically for
testing purposes, we need an equivalence relationship that can tell when
one XMLLiteral is the same as the other. However, u to now many
"concrete" suggestions for the value space have aimed at this
equivalence relationship and provided it by making the value space
"just another lexical form" - ie, just another representation.

There are reasons why you'd want to consider XML as "rich text" - I18N.
There are reasons why you'd want to treat it as something navigable with
the DOM.
There are probably even reasons why you'd want to consider it an octet
sequence, although they escpae me for the moment.
There are bugger-all reasons to exclude two out of three of the use
cases by picking just one of the above. Pat's option makes sense.

-- 
jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/
Tel +44(0)117 9287088 Fax +44 (0)117 9287112 http://ioctl.org/jan/
Goedel would be proud - I'm both inconsistent _and_ incomplete.
Received on Wednesday, 6 August 2003 07:51:18 EDT

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