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Re: Do resources have representations?

From: Sandro Hawke <sandro@w3.org>
Date: Tue, 29 Jul 2003 07:45:30 -0400
Message-Id: <200307291145.h6TBjUeV024723@roke.hawke.org>
To: Aredridel <aredridel@nbtsc.org>
cc: www-rdf-interest@w3.org


> http[s]://www.w3.org/ has metadata that states
> https://www.w3.org/key is a signature key for "Authoritative"
> information
> http://www.example.org/~foo/bla is/has metadata that states that
> http://www.w3.org/ and http://www.example.org/1234 are the same
> resource, and equivalent representations, and the statement is signed
> with the key https://www.w3.org/key, then your browser may have enough
> information (assuming that https://www.w3.org had a valid and trustable
> certificate) to direct (according to http://www.example.org/~foo/bla's
> instructions, authorised by https://www.w3.org/key) your browser to
> http://www.example.org/1234 should the situation merit (perhaps it is a
> more local mirror).
> 
> For that to happen, RDF needs a schema for signatures of statements
> (detached signatures as meta-statements, perhaps?), and a schema item
> for equivalent representations of a resource -- owl:isSameIndividual or
> whatnot, or perhaps a more specific, web-oriented namespace set -- a
> hypothetical w3:isSameRepresentationAs, (perhaps also w3:isMirrorOf and
> w3:ipTopologyLocation) or something equivalent.

This also comes up with the Galaxy example, or my earlier examples
about a URI for the Sun.  If we have two URIs for the Sun, we can
cleary say they are owl:sameAs each other -- that is, the meanings of
the two URIs are the same -- and yet in practice the URIs may behave
quite differentlty in your browser, so the URIs are demonstrably not
equivalent while their associated Resources are.  This is my argument
for why a URI that works unchanged (as by a redirect) in your browser
SHOULD NOT be used to identify something like the Sun.

In any case, it's not the URIs or the Representations that are
identical.  At best it's identity of associated ResponsePoints that
you want here.   But it's probably just some kind of equivalence, as
you suggest with :isMirrorOf:

   <http://web4.w3.org/> :mirrors <http://www.w3.org/>.

might be a good way to say (the true fact) that the browser experience
is meant to be the same, modulo network issues, using those two URIs.
But for that triple to make any sense in RDF, we have to consider the
URIs as identifying something like ResponsePoints [1].   If you go any
more abstract (like to "documents") then the :mirrors relationship is
meaningless. 

     -- sandro

[1] http://esw.w3.org/topic/ResponsePoint
Received on Tuesday, 29 July 2003 07:45:33 GMT

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