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Re: A triple is not unique.

From: Jonathan Borden <jborden@mediaone.net>
Date: Tue, 21 Nov 2000 08:10:11 -0500
Message-ID: <007501c053bc$61d7e5f0$0a2e249b@nemc.org>
To: "Pierre-Antoine CHAMPIN" <champin@bat710.univ-lyon1.fr>
Cc: "RDF-IG" <www-rdf-interest@w3.org>
Pierre-Antoine CHAMPIN wrote:

> Jonathan Borden wrote:
> > 1) Just because it is syntactically possible to assign an rdf:Statement
an
> > ID doesn't mean that it ought be allowable to assign more than one ID to
the
> > same statement.
>
> That is true.
> But unlike Brian McBride, I think the spec is not un ambiguous about
Reified statements (though it is precise about Statements).
> Now, assigning more than one URI to a statement is not only syntactically
possible, it is useful.
> Hence it would be great to officialy allow that.

    I agree that it is possible to have more than one reification quad
pertaining to the same statement, so I suppose that the ID of a statement
really pertains to the reified statement rather than the statement triple
itself.

>
> > 2) I strongly caution against trying to wrangle out of this issue using
the
> > "can a resource have multiple URIs" question which rears its head from
time
> > to time. Using the RFC 2364 definition of URI it is clear that the
resource
> > identified by a URI may be abstract and hence *even when 2 URIs resolve
to
> > the same network entity*, each URI still identifies a distinct abstract
> > resource. The distinction between the resource identified by a URI and
an
> > entity retrieved when a URI is resolved is clearcut.
>
> I still agree with you.
> But the quetion you quote maybe hides a deeper one : "does RDF describe
only resources, or does it also describe entities".
> My guess is that when a resources resolves to a unique entity, it is very
tempting to describe the entity rather than the resource -- and I'm pretty
sure some RDF users already did.
>

    Perhaps but we need to be very careful about ascribing behavior to or
assuming properties of resources which don't exist. For example:

http://www.w3c.org/
http://WWW.w3c.org/
http://wWw.w3c.org

each describe different resources though when resolved by the DNS system
always resolve to the same protocol and IP address. Yet from day to day or
hour to hour the homepage of the W3C may change, so there is never an
*implicit* identity between a URI and a resolved network entity as defined
by an HTTP MIME response at the character level.

So, for the purposes of RDF these are 3 different resources! ... although
rdf:Alt does come to mind :-))

Jonathan Borden
The Open Healthcare Group
http://www.openhealth.org
Received on Tuesday, 21 November 2000 08:22:16 GMT

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