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Thomas B. Passin scripsit:
> I think that much confusion has arisen when non-retrievable URIs got into
> the mix. On top of this, RDF uses the term "Resource" in a specialized way,
> so that it does not really mean the same thing as a "resource" in the first
> story. When a URI is non-retrievable and is used to "identify" something
> non-retrievable - it may be the Yosemite valley or some intangible concept
> or whatever, then there is no act of emitting a representation that is ever
> going to happen.
Ah, but there is. There is no *intrinsic* difficulty in
saying that what you get when you perform a GET on the URI
http://www.ibiblio.org/wm/paint/auth/vinci/joconde/joconde.jpg ,
for example, is a representation not merely of a particular document,
but of a particular painting, and for that matter a particular woman.
Neither the model nor the painting are on the network, of course. These
reps of reps and reps of reps of reps are where the difficulties arise.
The question then is: when we use that URI as the subject (WLG) of an
RDF triple, which of the three are we predicating about? The document,
the painting, or the woman? RDF makes it impossible to say.
Topic maps at least sharply distinguish between assertions about documents
and assertions about the subject matter of documents, though it remains
outside the system whether a JPEG such as this has the painting or the
woman as its subject matter.
--
John Cowan
jcowan@reutershealth.com
I am a member of a civilization. --David Brin
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