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RE: HTTP URIs for real world objects

From: Peter F Brown <peter@pensive.eu>
Date: Thu, 17 Jan 2008 08:04:23 +0100
Message-ID: <1B2253B0359130439EA571FF30251AAE072D73@SBS.pensive.lan>
To: "Peter Ansell" <ansell.peter@gmail.com>, "Bernard Vatant" <bernard.vatant@mondeca.com>
Cc: "Danny Ayers" <danny.ayers@gmail.com>, Reto Bachmann-Gmür <reto@gmuer.ch>, "Leo Sauermann" <leo.sauermann@dfki.de>, <public-sweo-ig@w3.org>, <semantic-web@w3.org>

I don't think the issue is as simple as that. You are right about the OASIS spec (which, if memory serves correctly, didn't make it through to approval as a standard and sits a little uncomfortably as a "recommendation" that doesn't have the authority of its namesake in W3C) but that underlined precisely one problem for both camps: what authority can make assertions about the identify of proxies for real-world subjects? In practice, it doesn't matter as the recommended (but by no means mandatory) guideline for establishing "ownership" of any claim is the namespace.
The published subject identifier (PSId) is merely a mechanism for making an assertion that "in this neck of the woods, we define this thing this way" but with one important and significant provision: any conformant processor must assume that any two topics, whatever their names or other 'properties', refer to the same real world subject if they carry the same identifier. RDF has no such - pragmatic - mechanism. The reliance on the use of the law of identity doesn't help as it assumes that for any two things, you can only assert that they are identical if the set of their properties are equivalent, an assertion that is difficult to sustain if one does not know the entire set of properties (and, in many real-world situations, the complete set of such properties is possibly unknowable).
It comes down to an issue of governance, who asserts what and with what authority, and bland assertions that the world is going to populated by happy RDF triples will not make that issue go away.
The subject of this thread is about URIs for real world "objects". RDF's fatal flaw in this respect is that it makes no distinction between use and mention of a subject (think Alice Through the Looking Glass and "the name of the song" - Lewis Carroll knew what he has talking about). I would still maintain that PSIds answer that requirement unequivocally, however poorly it might be considered that the documentation supports that view.


(same name, another subject...)

-----Original Message-----
From: Peter Ansell [mailto:ansell.peter@gmail.com] 
Sent: 17 January 2008 02:53
To: Bernard Vatant
Cc: Peter F Brown; Danny Ayers; Reto Bachmann-Gmür; Leo Sauermann; public-sweo-ig@w3.org; semantic-web@w3.org
Subject: Re: HTTP URIs for real world objects

And to think we haven't gone anywhere since 2003, except for away from
Topic Maps it seems. It was particularly noticeable that OASIS didn't
specify how to publish specifications, only that you should if you
want to use their mechanism. The difference between the figures in
Sections 2.3 and 2.4.4 would not be recognised by a pragmatist looking
at the document as it is without any discussion of publication

Before standards boards realise it there is going to be a de-facto
standards with single simple RDF http resources backed up by OWL
documents to define the vast majority of the Semantic Web.


On 17/01/2008, Bernard Vatant <bernard.vatant@mondeca.com> wrote:
> Thanks Peter for the reminder
> There is also a separate OASIS recommendation on Published Subjects,
> defining "published subject identifiers" and "published subject indicators".
> http://www.oasis-open.org/committees/download.php/2897/pubsubj-pt1-1.01-cs.pdf
> Bernard
> Peter F Brown a écrit :
> > There are HTTP URIs for real world objects: they are called "subject identifiers" and form part of the ISO 13250 Topic Maps standard, where a 'Topic' is a proxy for any real world subject, and a Topic can take 0 to a URIs as subject identifiers...
> > Its sometimes really hard keeping things simple, but when There is something There that works , please use it and don't fall victim of the 'Not Invented here' syndrome. Regards, Peter
> >
> --
> *Bernard Vatant
> *Knowledge Engineering
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Received on Thursday, 17 January 2008 07:04:40 UTC

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