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Re: A shot at http://www.w3.org/2000/03/rdf-tracking/Overview.html#rdfms-resource-semanti cs

From: <jos.deroo.jd@belgium.agfa.com>
Date: Wed, 9 May 2001 16:45:32 +0100
To: aswartz@upclink.com
Cc: jos.deroo.jd@belgium.agfa.com, bwm@hplb.hpl.hp.com, martyn.horner@profium.com, w3c-rdfcore-wg@w3.org
Message-Id: <OF7750EEB7.0051048D-ON41256A47.003EE065@bayer-ag.com>


> >  Two resources r1 and r2 can be mapped by D to the same entity.  In that
case
> >  we say they are equivalent.
>
> I think this is a mistake -- there are many pages which return the same
> entity (the same set of text) but we cannot assume from this that they have
> equivalent resources. To do so would be a grave mistake.
> The entity returned may vary over time while the resource stays the same.
> Just because at one point in time they return the same entity does not mean
> that they always will.

maybe not if we talk about set-of-entities
which could go like:

  there is a set of resources called R
  there is a set of uris called U
  there is a function f:U->R
    for all u element of U there exists a r element of R such that f(u) = r
    (or we could represent a resource r as a skolem function of it's uri u)
    so u1 = u2 => f(u1) = f(u2)
    so u1 = u2 => r1 = r2

  there is a set of set-of-entities called S
    (s element of S is meant to represent the possible states of a resource)
  there is a function g:R->S
    for all r element of R there exists a s element of S such that g(r) = s
    for all u element of U there exists a s element of S such that g(f(u)) = s
    so u1 = u2 => s1 = s2

--
Jos De Roo, AGFA http://www.agfa.com/w3c/jdroo/
Received on Wednesday, 9 May 2001 10:48:22 EDT

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