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

From: Graham Klyne <GK-lists@ninebynine.org>
Date: Thu, 18 Jan 2001 21:56:32 +0000
Message-Id: <>
To: Seth Russell <seth@robustai.net>
Cc: Tim Berners-Lee <timbl@w3.org>, RDF-IG <www-rdf-interest@w3.org>
At 10:48 AM 1/18/01 -0800, Seth Russell wrote:
>Tim Berners-Lee wrote:
> > Oh, that sounds like an anonymous node. This is just an existentially
> > quantifiued variable.
> >
> > <> foo:replyTo [ foo:writtenBy
> >     [ foo:mailbox  <mailto:seth@robustai.net> ; foo:firstname "Seth" ]
> > ]
> >
> > which you can read as "This document is a reply to something which
> > was written by that which has email address mailto:seth@robustai.net
> > and first name "Seth". Maybe that is what you mean.
>Ok, we could use an entire node rather than just a uri string, i hadn't though
>of that.  But the application requires that we explicitly state that the 
>node is
>a variable, an Unknown, a blank line in a forum that we are soliciting 
>agents to
>fill out.  ...

OK, I'm going to wade in...

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.

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.)

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.

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.

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.

The particular virtue of this approach is that it doesn't require any 
change to the core definitions of RDF -- the required features can be 
created in the superstructure.

Received on Thursday, 18 January 2001 17:33:27 UTC

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