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Re: Proposal: #rdfms-identity-anon-resources

From: Brian McBride <bwm@hplb.hpl.hp.com>
Date: Mon, 23 Jul 2001 06:37:25 +0100
Message-ID: <3B5BB815.4351E211@hplb.hpl.hp.com>
To: Dan Connolly <connolly@w3.org>
CC: Aaron Swartz <me@aaronsw.com>, Graham Klyne <Graham.Klyne@Baltimore.com>, RDF core WG <w3c-rdfcore-wg@w3.org>
DanC makes concrete a fundamental philosophical point:

  An RDF processor can never know enough about the real world to decide
  that two anonymous descriptions were intended to describe the same
  resource.

Thus, if an RDF processor is ever to generate a URI for an anonymous
resource, it must never use the same URI twice, otherwise it risks
asserting that two different resources are in fact the same.

The only algorithms that it can use therefore are those that generate
(probably) unique identifiers each time they are called such as uuidgen.

Brian


Dan Connolly wrote:
> 
> Aaron Swartz wrote:
> >
> > On Wednesday, July 18, 2001, at 01:21  PM, Dan Connolly wrote:
> >
> > > I've noodled on the approach of naming things based on their
> > > XML element position, and I've convinced myself that won't
> > > work either. I don't have a proof that there's no such algorithm,
> > > but I'm not likely to spend more time thinking about it until
> > > somebody makes a concrete suggestion (i.e. running code)
> > > of an algorithm that works.
> >
> > Umm, what about the one built in to SiRPAC and most other RDF
> > parsers. It will reliably generate the same numbered anonymous
> > nodes for the same RDF/XML input.
> >
> > http://www.w3.org/RDF/Implementations/SiRPAC/
> > http://zoe.mathematik.Uni-Osnabrueck.DE/RDF/parser.html
> 
> But that algorithm generates the same identifier for lots
> of different inputs.
> 
> consider doc1, which says:
> 
>         I'm thinking of something.  [sirpac generates: doc1#_g1 ]
>         It's greater than 5.    [ sirpac spits out: <doc1#g1>
> math:greaterThanNumeral "5" ].
> 
> then I edit doc 1 and feed it to SIRPAC again:
> 
>         I'm thinking of something.  [sirpac generates: doc1#_g1 ]
>         It's less than 5.       [ sirpac spits out: <doc1#g1> math:lessThan "5" ].
> 
> the documents I wrote down didn't conflict with each other:
> I was thinking of different somethings.
> 
> But the triples that sirpac generates when parsing them do
> conflict: they say that the very same something is
> both less than 5 and greater than 5.
> 
> The identifier has to carry all the information that
> was said about it in order to "work", no?
> 
> p.s. if you don't like my informal "I'm thinking of something"
> syntax, it's mnemonic for:
> 
>         <rdf:Description>
>                 <math:greaterThanNumeral>5</math:greaterThanNumeral>
>         </rdf:Description>
> 
> and
> 
>         <rdf:Description>
>                 <math:lessThanNumeral>5</math:greaterThanNumeral>
>         </rdf:Description>
> 
> --
> Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Monday, 23 July 2001 01:40:01 EDT

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