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Re: A triple is not unique.

From: Jonathan Borden <jborden@mediaone.net>
Date: Mon, 20 Nov 2000 13:41:29 -0500
Message-ID: <027701c05321$9f06e7f0$0a2e249b@nemc.org>
To: "Dan Brickley" <Daniel.Brickley@bristol.ac.uk>, "McBride, Brian" <bwm@hplb.hpl.hp.com>
Cc: "Seth Russell" <seth@robustai.net>, "RDF-IG" <www-rdf-interest@w3.org>
Dan Brickley wrote:

> On Mon, 20 Nov 2000, McBride, Brian wrote:
> > I can see that the disruption caused to current implementations
> > would be a factor if m&s was ambiguous.  But if the answer lies
> > in m&s, I humbly suggest the spec takes precedence.  That's what
> > specs are for.
> Maybe I missed the appropriate post, but I'm unclear how we square the
> set-oriented definition of 'Statement' with the syntactic ability to
> assign various IDs (and hence URIs) to the XML occurances of RDF
> statements. Or rather, I suspect we could do this, by adopting a strong
> view on the "can a resource have multiple URIs" question that
> periodically bedevils discussion here and elsewhere.

This is looking more and more like a gaping hole growing between the model
and syntax parts of the specification.

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.

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.

This view has already been definitively stated in RFC 2364 however if Tim BL
himself wishes to update the definition of a URI in order to solve this
apparent problem in the RDF rec I am all ears. In the meantime this issue
can be laid to rest by clarifying the uniqueness of a statement as defined
by (p,s,o)

Jonathan Borden
The Open Healthcare Group
Received on Monday, 20 November 2000 13:56:01 UTC

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