W3C home > Mailing lists > Public > www-rdf-interest@w3.org > January 2001

Re: Proposal: variables, templates, and Stickey Cyber Molecules

From: Seth Russell <seth@robustai.net>
Date: Thu, 18 Jan 2001 19:59:34 -0800
Message-ID: <3A67BBA6.B0362097@robustai.net>
To: Graham Klyne <GK-lists@ninebynine.org>
CC: Tim Berners-Lee <timbl@w3.org>, RDF-IG <www-rdf-interest@w3.org>
Graham Klyne wrote:

> I think it is possible to achieve this effect without requiring an explicit
> indication that the node is a "variable", although I think there is a need
> to indicate the scope withi which the value/name bindings associated with a
> node may be applicable.

I responded to this in my last email; but further on you raise some very
interesting points.

> If one has a node whose URI is unknown, then I propose to just assign it a
> unique URI.  (I find that leaving the node anonymous is unsatisfactory
> because one may wish to establish that different occurrences within a
> context are indeed the same thing.)

This is where I think we need to draw a distinction between internal and external.
Most implementations assign a unique identifier to any node they create (anonymous
or not); the question, I think, is whether it is wise to publish that unique
identifier to the outside world as a URI.  I would weigh in on the side that it is

> Then what shall we do when we later discover further information
> establishing that this resource node, which has by now been bound to a URI,
> is in fact the same as some other resource in some wider context, which
> also has a (different) URI.

Well internally if you discover that they should be the same node you just :Smush
them together and revise all the internal pointers accordingly.  If you haven't
published a uri for either of them externally then there is no problem whatsoever.

> One answer is to declare that the two URIs are in fact bound to the same
> resource.  But this goes against the view held by some that URI:Resource
> mapping is 1:1-onto.

If you cannot draw a distinction between two nodes, then they should have the same
internal identifier.  What the outside world does is pretty close to  chaos; but
when you publish to it, and are consistent, then that helps to simplify the chaos.

> A more flexible approach is to draw on some idea of resource equivalence
> that allows us to infer properties of one resource from the corresponding
> properties of another resource with which it is equivalent.  This is the
> approach I am planning to take in my work.

Hmmm....  this works internally and externally; however it does require that a
whole slew of equivalences be published along with your statements.  From whence is
the infrastructure for this kind of thing going to arise?

:Seth :wants [a :Programmer, :Unknown] ;  Now!!
Received on Thursday, 18 January 2001 22:52:41 UTC

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