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Re: Model-specific identity for anon resources, and its representation: A new issue?

From: pat hayes <phayes@ai.uwf.edu>
Date: Tue, 26 Jun 2001 13:03:30 -0500
Message-Id: <v04210108b75e7cedbea7@[]>
To: Jan Grant <Jan.Grant@bristol.ac.uk>
Cc: w3c-rdfcore-wg@w3.org
>On Mon, 25 Jun 2001, Aaron Swartz wrote:
> > On Saturday, June 23, 2001, at 11:25  PM, pat hayes wrote:
> >
> > >>> I don't agree that anonymous nodes should be part of the abstract
> > >>> syntax, and would suggest to consider this issue when cleaning up the
> > >>> model.
> > >> I tend to agree with this position. However, I would take it
> > >> one step further -- I believe that these "uniquely generated
> > >> resources" should have consistent, repeatably generated URIs.
> > >> That is, all parsers should assign the same genid to the same
> > >> resource.
> > > Can you say why you want this?
> >
> > Sorry for the confusion, I'm having trouble expressing the last
> > sentence. How about:
> >
> > "That is, all parsers should assign the same genids to the same
> > anonymous resources in the same document."
> >
> > Or better, that all parsers generate the same triples for each
> > document. This does a number of things:
> >
> >   - It gets the notion of anonymous resource out of the abstract syntax
> >   - It makes parsers interchangeable
> >   - It allows triples to be compared with a simple sort/diff
>Not really, no. You _still_ are going to need anonymous resource
>resolution/unification in there somewhere: for example, if you decide
>that two documents (or the same documentat two different URLs) are
>talking about the same things.

AHA!  I see what y'all mean by 'unification' and why I wasnt 
following it. You are talking about what logic calls equality or 
identity. Unification (in logic and logic programming) means making 
two terms the same by substituting terms for (universally quantified) 
variables in the syntax. Equality doesnt make two terms or names the 
same as a syntactic operation, it just asserts that the (different) 
terms or names denote the same thing, by asserting an equality 
statement of the form (= termone termtwo) (in our case that would be 
done by rdf:equivalent, I assume). So if two different URIs 
(anonymous or not) are talking about the same thing, then it would be 
correct to assert an equality or equivalence using them and it would 
be correct to infer anything that was asserted about one of them 
about the other one.  But all that is not the same as *unifying* 
them. Once you unify two expressions they are the *same expression*, 
not two expressions talking about the same thing.

Pat Hayes

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Received on Tuesday, 26 June 2001 14:03:31 UTC

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