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Re: A triple is not unique.

From: Seth Russell <seth@robustai.net>
Date: Mon, 20 Nov 2000 12:17:41 -0800
Message-ID: <3A1986E5.A5897749@robustai.net>
To: Jonathan Borden <jborden@mediaone.net>
CC: Dan Brickley <Daniel.Brickley@bristol.ac.uk>, "McBride, Brian" <bwm@hplb.hpl.hp.com>, RDF-IG <www-rdf-interest@w3.org>
Jonathan Borden wrote:

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

I agree.

> 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.

I agree.  But if somebody does assign an ID (uri?) to a statement, then I think
they are expressing a clear intent  to speak about one particular unique
occurrence of a [s,p,o].  Whereas if they only identify the triple [s,p,o]
anonymously, then they are talking about any such statement which might occur
such that it matches the other qualifiers that hang off of their node.  If they
assign multiple ID's to the same [s,p,o], they must either be talking about
different occurrences of that triple, or they must be very confused.  If you
refer to the exact same properly qualified proposition as do I, then if you know
my URI you should use it if you are talking to me.

> 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.

If I assign a URI to a statement, I am talking about a particular occurrence of
that statement, not the 'abstract thing' to which it may refer.  Perhaps that is
only the philosophy of my particular implementation.  If I find a RDF statement
floating around the internet, I am in exactly the same predicament  as when I
find a natural language statement floating into my ears.  It is up to me to
interpret whether it refers to anything at all.  I don't think M&S can legislate
anything different, nor do I think it does.  Like Dan says "How would you police
that?"  and who would want it policed?

> 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)

Relative to which semantic island are you referring to this uniqueness property?

Seth Russell
Received on Monday, 20 November 2000 15:16:20 UTC

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