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Re: article on URIs, is this material that can be used by the SWEO IG?

From: John Cowan <cowan@ccil.org>
Date: Wed, 30 May 2007 22:32:09 -0400
To: Pat Hayes <phayes@ihmc.us>
Cc: John Cowan <cowan@ccil.org>, Leo Sauermann <leo.sauermann@dfki.de>, www-tag@w3.org
Message-ID: <20070531023209.GE11862@mercury.ccil.org>

Pat Hayes scripsit:

> > For example,
> >http://en.wikipedia.org/wiki/Shakespeare is a subject indicator for
> >Shakespeare.
> But it also mentions Stratford-on-Avon, Mary Arden, and many other 
> things. Why is it not just as much 'about' them?

Because I don't so employ it.  In principle it could be.  In my judgment,
there are other clearly better subject indicators for those resources.

Two resources identified by the same subject identifier (or
in fact with the same subject-indicator-reference URI)
are the same.

> And what does THAT mean? This notion of a thing's "identity" seems to 
> be very freely used in W3C circles, but I have no idea what it is 
> supposed to mean. What kind of things have an "identity"? Does a 
> grain of sand on a beach have an identity? It is certainly identical 
> to itself: is that enough?

Yes, in principle, but we don't worry about the identity of things
which are not the subject of any predications.  If I go to the water
tap and fill a cup with water, there is now a glob of water of which
we can say "It is in the cup".  Before, there was no such "it";
the glob of water lacked any useful identity.

> Apparently Shakespeare has an identity, 
> but I wouldn't recognize him if I were to meet him in the street. If 
> someone were to tell me something about Shakespeare I would indeed 
> feel that I knew who the fact was 'about', but is this anything more 
> than just familiarity with the name?

There are lots of facts we can predicate about Shakespeare; his life
is rather well-documented for a person of his place and time.
Some people assert that some of these facts are wrongly predicated
about Shakespeare, like "wrote Hamlet".  Nobody, as far as I know,
says that Hamlet was written by some totally unknown person, but
if it turned out to be true, that person would be identified as
separate from Shakespeare.

> I would feel the same if someone 
> were to use the name, say, "Rauschenberg", but about all I know about 
> Robert Rauschenberg is that he is, or was, a notable American 
> contemporary artist. Is this enough to give him an "identity"? How 
> much information about a thing is enough to establish an identity for 
> that thing?

If there is something you can assert about Rauschenberg, like "is a
notable contemporary artist" or even "is named 'Robert Rauschenberg'",
then at least you know that he is not Willem de Kooning or Buckminster
Fuller or Paganini.

On the Semantic Web, it's too hard to prove     John Cowan    cowan@ccil.org
you're not a dog.  --Bill de hOra               http://www.ccil.org/~cowan
Received on Thursday, 31 May 2007 02:32:34 UTC

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