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RE: what RDF is not (was ...)

From: Miles Sabin <msabin@interx.com>
Date: Fri, 4 Jan 2002 16:06:34 -0000
To: <www-rdf-interest@w3.org>
Message-ID: <69B15B675E99D411A4110008C786DA23020CC907@exwest_01.interx.com>
Mark Baker wrote,
> No problem, because it has identity.
>
> http://example.org/msabin/line/segment/all

Sorry, but you'll have to explain to me _why_ this URI has anything
to do with the original line or any of it's segments (I'll assume 
you've assigned the line itself http://example.org/msabin/line/).

I assume you've adopted some private convention which gives URIs of 
the form "prefix/F/all" semantics something like,

  for all x in prefix such that Fx ...

I don't share that convention, and it pretty clearly goes way beyond 
anything you'll find in either RFC 2396 and RDF(S). If it didn't, we 
wouldn't need DAML.

You're confusing two quite distinct questions,

1. Whether or not finite strings of symbols can be used to represent
   propositions concerning an infinite number of subjects.

2. Whether a countably infinite set of names is big enough to assign
   everything a unique name.

The answer to (1) is, yes, clearly you can, in any language which has
universal quantifiers. But neither RFC 2396 nor RDF have universal
quantifiers (hence the need for DAML).

The answer to (2) is, no, as Peters diagonal argument shows.

I'm afraid you've fallen victim to the "fallacy of composition" by 
inferring that _everything_ can have a unique name at the same time 
from the incontrovertible fact that _anything_ can have a unique name. 
That's no more valid than concluding that because anybody could be
above average, then everybody could be.

Cheers,


Miles

-- 
Miles Sabin                                     InterX
Internet Systems Architect                      27 Great West Road
+44 (0)20 8817 4030                             Middx, TW8 9AS, UK
msabin@interx.com                               http://www.interx.com/
Received on Friday, 4 January 2002 11:07:40 GMT

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