W3C home > Mailing lists > Public > www-rdf-logic@w3.org > August 2001

Re: Summary of the QName to URI Mapping Problem

From: Piotr Kaminski <pkaminsk@home.com>
Date: Thu, 16 Aug 2001 16:05:30 -0700
Message-ID: <009b01c126a9$94b06040$35254d18@gv.shawcable.net>
To: <www-rdf-logic@w3.org>
Pat Hayes asked:
> This seems to me to be the basic issue: who has the authority to say
> they are distinct?

In other words, who gets to decide what a name identifies?  The generally
accepted answer on the web is that if the name has an authority component
(i.e. a host name), then the (current) owner gets to decide.  You can of
course ignore the owner's edict and make up your own mind.  (If the owner is
spouting contradictions, that might be a good idea!)  If multiple
authorities make claims about a name, you have to decide which one to trust.

I wouldn't trust the RDF spec with regards to identity, though.  If I write
up a nice XML document with non-identical QNames from a namespace whose
domain I own, the XML Namespaces spec allows me to claim that they identify
different things.  Along comes RDF, concatenates the pairs, and concludes
that the QNames identify only one thing.  It contradicts the document's
author, whose claim was perfectly valid based on the standard definition of
QNames.  This is a bad thing.

> If they really were distinct, that is. Or, you could take the
> position that the use of the mapping shows that they couldn't have
> been distinct.

That indeed seems to be the position of people defending the current
mapping.  It's not a problem as long as everybody agrees to it.  However,
since the mapping is not part of the XML Namespaces spec, and not everybody
uses the RDF interpretation, I don't think this is something we can impose
on the rest of the world.  And if RDF chooses to use this mapping within its
own space, then its definition of QName is no longer compatible with
everybody else's.

        -- P.

  Piotr Kaminski <piotr@ideanest.com>  http://www.ideanest.com/
  "It's the heart afraid of breaking that never learns to dance."
Received on Thursday, 16 August 2001 19:13:10 UTC

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