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Re: TAG request: establish the relationship between URIs and Resources is many to many

From: Tim Berners-Lee <timbl@w3.org>
Date: Thu, 23 Jan 2003 23:02:03 -0500
Cc: www-tag@w3.org
To: Bill de hÓra <dehora@eircom.net>
Message-Id: <98E61D3C-2F50-11D7-B288-000393914268@w3.org>

IMHO

On Thursday, Jan 23, 2003, at 07:24 US/Eastern, Bill de hÓra wrote:

>
> To the TAG,
>
> In an effort to cut to the chase and get some software build and 
> deployed that uses RDF technology, I would like to TAG to advise on 
> the structural relationship between URIs and what it is they identify, 
> namely the Resources (hereafter 'things').

The TAG was at one point writing up some basic axioms about URIs
and I am not sure what happened to it. But an essential one was that
the same URI represents the same thing irrespective of context.

> I offer an opinion. The relationship between URIs and things is many 
> to many. One URI will be used to denote many things. A thing will be 
> denoted by many URIs.
>
> I offer a rationale for this opinion. It's preferable to constrain the 
> relationship to one to many, as this results in simpler, deterministic 
> software. However I believe the notion that a URI only ever identifies 
> one thing, however appealing, is fictitious, and an shackle on the 
> semantic web that will lead to unscalable systems and fringe benefits, 
> in much the same way backlinking sidelined hypertext until the web was 
> invented without the backlinking constraint.

I disagree.   You say, "in much the same way" but you give no analogy to
explain a link between the two cases.  The web works because
when you make a link you assume that the URI which the publisher of
the target document gave you will, anywhere in the world,
identify the same web page. You quote the URI, and it stands for the 
page.
Other URIs might identify an equivalent page, but that is immaterial.
The relationship URI to web page is many to one, and that is esential to
the working of the web, and equally essential to the working of the 
semantic web.

> the many to one relationship will not hold, nor is manageable across 
> the number of authorities the web encapsulates, leading to ambiguous 
> and outright inconsistent data sets shared across a gloabl system that 
> is by definition not architected to be resilient to inconsistency. 
> Hence I encourage to TAG to advise the relationship is many to many.

Encourage you can, but I can't see the TAG robbing the URI of its 
characteristic that it identifies.

It may be that there are specific scenarios which you have in mind. Are 
you concerned about misinformation of the semantic web leading to 
inconsistency?  Are you concerned about malicious stealing of URIs? I 
think the semantic web systems will clearly have to be able to cope 
with these things, but not by breaking the idea of URIs.

> I have no affilations currently with any W3C activities.
>
> regards
> Bill de hÓra
Received on Thursday, 23 January 2003 23:01:49 GMT

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