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Re: Action: #rdfms-identity-anon-resources questions

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Mon, 23 Jul 2001 07:40:12 +0100
Message-ID: <3B5BC6CC.4E50986F@hplb.hpl.hp.com>
To: Graham Klyne <GK@NineByNine.org>
CC: RDF core WG <w3c-rdfcore-wg@w3.org>


Graham Klyne wrote:

[...]
> 4. Can we agree whether or not unique generated IDs (in the style of Skolem
> constants) are equivalent to existentially quantified variables for the
> purpose of asserting the existence of a resource with properties
> given?  (See Frank's message [10] for a discussion -- I discount the option
> of dropping anonymous resources.)

This is the key question.  I suggest we have established the following 
differences between a resource named by a URI and a resource identified
by a quantified variable:

  o scope:  An application given a resource identified by a URI
    can reasonably expect to pass that URI to other applications and
    that they should be able to recognise it - c.f. my example
    on seeking references about a service offered in response to an ad.

    If the response includes a reference to a service identified by
    a URI, the receiver could reasonably pass that URI to reference
    service to seek a credit/quality reference for that service.
    There is no point doing that for a variable.

  o binding: An application given a resource identified by a URI
    can assume that URI denotes a specific resource - the
    binding decision has been made - an existentially quantified
    variable has not been bound to a specific resource.

  o provenance: when a source of rdf states some properties about
    a resource named by a URI it is making assertions that the
    resource named by that URI has those properties.  when a source
    of rdf states properties about a variable, it is making no
    assertions about the name of that resource.

Brian
Received on Monday, 23 July 2001 02:42:49 EDT

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