W3C home > Mailing lists > Public > www-rdf-interest@w3.org > November 2000

RE: A triple is not unique.

From: McBride, Brian <bwm@hplb.hpl.hp.com>
Date: Mon, 20 Nov 2000 22:42:55 -0000
Message-ID: <5E13A1874524D411A876006008CD059F2394E1@0-mail-1.hpl.hp.com>
To: "'Dan Brickley'" <danbri@w3.org>
Cc: Jonas Liljegren <jonas@rit.se>, Seth Russell <seth@robustai.net>, RDF-IG <www-rdf-interest@w3.org>
> > Just because an expression is syntactically valid, does not mean it
> > is a valid expression of a language.  Consider C, many syntactically
> > valid "program" violate other contraints of the language and are
> > illegal.
> I'd like to think I appreciate that! My concern (see reply to 
> Jonathan) is
> that we don't want the status of the expression to depend on 
> the content
> of utterly unrelated RDF files elsewhere on the Web which 
> happen to also
> encode the same p/s/o content but (via the ID mechanism) assign them a
> different identifier. Imagine if your C program became illegal when
> someone else far away on the Web wrote C that attempted to do 
> something
> that overlapped with your application. <shudder/>
> So that's the problem: if there's only one resource of type
> rdf:Statement with any given p/s/o, and RDF  syntax is useful 
> enough to
> provide a way of ascribing identifiers to those things, whose chunk of
> syntax gets to be the lucky markup that names some given 
> triple? How do we
> know that the rest are violating some constraint? Or should 
> we be careful
> and say they're ALL in voilation?

Fair enough.  I was trying to keep this out of the how many URI's 
can a resource have debate.  Failed again!  :)

So I see two options.  A resource can have multuple URI's in which
case the ability to assign multiple URI's to the same reified
statement is no problem.

Option 2, resources can have only 1 URI, in which case there can be
multiple resources which model an RDF statement, but they are all
equivalent, as in DAML equivalentTo.

In this respect, are statements any different from, say trees.
Web principles say that I can start creating URI's that name trees
in the park, but so might you and so might Graham.  Either trees
are modelled by resources that can have multipel URI's or there
can be multiple equivalent URI's modelling the same tree.

Received on Monday, 20 November 2000 17:43:02 UTC

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