W3C home > Mailing lists > Public > uri@w3.org > September 2002

Possible new issue: Things with and without identity?

From: Miles Sabin <miles@milessabin.com>
Date: Mon, 9 Sep 2002 19:44:27 +0100
To: uri@w3.org
Message-Id: <200209091944.27191.miles@milessabin.com>

A discussion point from the rest-discuss list which is probably better 
dealt with here,

  http://groups.yahoo.com/group/rest-discuss/message/2465

At issue is the first sentence of the informal definition of resource in 
RFC 2396 1.1,

  A resource can be anything that has identity.

"that has identity" is redundant because *everything* has identity in 
the only reasonably straightforward understanding of identity, ie. the 
logical truth in all but the most obscure formal systems that,

  (Vx) x = x

Even though redundant, this qualifier has had the unfortunate 
consequence of leaving this sentence open to wildly different 
interpretations,

* It has been read as implying that the set of possible resources is a
  subset of the set of things: the subset that has identity as opposed
  to the subset that doesn't. Dan Brickley reports that this confusion,
  and the subsequent hunt for things which *don't* have identity and
  some means for identifying them, has caused trouble in RDF circles.

* It has been misread as,

    A resource can be anything that has an identifier (eg. a URI).

* It has been misread as,

    A resource can be anything that can be identified (via some
    effective mechanism).

I don't believe that any of these were the authors intent, so to clear 
up any confusion, the "that has identity" qualifier should be dropped.

That still leaves open the question of whether or not the residual,

  A resource can be anything.

is either true or makes sense. This is controversial, no doubt, but it's 
better not to have the controversy obscured by a distracting 
qualification.

Cheers,


Miles
Received on Monday, 9 September 2002 14:45:04 UTC

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