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RE: We don't need no stinkin' identity

From: Michael Mealling <michael@neonym.net>
Date: 27 Apr 2003 12:01:00 -0400
To: pat hayes <phayes@ai.uwf.edu>
Cc: Larry Masinter <LMM@acm.org>, uri@w3c.org
Message-Id: <1051459259.9235.235.camel@blackdell.neonym.net>

On Sat, 2003-04-26 at 19:25, pat hayes wrote:
> >First,
> >>  note that the _semantics_ of a URI are not defined in
> >>  this specification. Each URI scheme itself defines the
> >>  relationship between URIs of that scheme and the resources
> >>  they identify. In all known cases, that definition isn't
> >>  enough to allow the URIs of that scheme to be used, by
> >>  themselves, as unambiguous identifiers when trying to
> >  > make logical assertions.
> 
> Again, the problem is not that the logic requires unambiguity; quite 
> the reverse, in fact: it is that imposing unambiguity as a defining 
> characteristic of URIs is logically incoherent.
> 
> Suggested modification, without the logic-bashing:
> 
> >  What is a Resource? Can a URI be used to identify a Concept?
> 
> >  This specification does not define the word 'resource' carefully,
> >  nor does it define how a URI can be used to 'Identify' a
> >  'Resource'. The _semantics_ of a URI are not defined in
> >  this specification.  Each URI scheme itself defines the
> >  relationship between URIs of that scheme and the resources
> >  they identify or refer to.
> 
> The reason for the last three words is that it doesn't make sense to 
> say that a URI identifies a *single* thing, in almost any logical 
> language. (In fact, it doesn't make much sense in any language, IMO, 
> but leave that aside for now.)

Pat, 
  I think that's one of the places that we're falling down on our
explanation. You assert that it doesn't make sense "in almost any
logical language". And that's the point, URIs aren't _in_ a logical
language, they exist outside all of them. URIs may be used _by_ a
language but at that point it is incumbent on the language/system that
uses them to define what it means concerning the things that URIs are
allowed to identify. 

  As Graham has pointed out before, the problem here is that RDF, SW,
OWL, etc have erroneously attempted to inherit RFC 2396's concept of
Resources unmodified, and that was a severe mistake. IMHO, it is
probably worth inserting language into the new document suggesting that
it is extremely dangerous to simply inherit this definition of a
Resource without some sort of system specific profile of it. Systems can
do it but they have to be very clear that they are inherit it, not the
other way around...

  To simply inherit this documents concept of a Resource would be the
network equivalent of simply specifying an application layer (8)
protocol directly on top of IP, ignoring its admonitions to use things
like TCP/UDP/ICMP, etc that constrain IP to something that is usable by
higher layers.

-MM
Received on Sunday, 27 April 2003 12:04:22 GMT

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