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Re: Action: #rdfms-identity-anon-resources questions

From: Graham Klyne <Graham.Klyne@Baltimore.com>
Date: Wed, 25 Jul 2001 15:51:14 +0100
Message-Id: <5.1.0.14.2.20010725154122.03425070@joy.songbird.com>
To: pat hayes <phayes@ai.uwf.edu>
Cc: Brian McBride <bwm@hplb.hpl.hp.com>, w3c-rdfcore-wg@w3.org
At 10:15 PM 7/23/01 -0700, pat hayes wrote:
>It isnt clear to me what the scope of anonymous node is intended to be, 
>but it if it is the document containing the node, then indeed it should be 
>impossible for any other source to say anything about the thing it refers 
>to, so this is a genuine difference. However, the same is true of a 
>non-anonymous URI if its use is restricted to this one source.

I've been thinking recently about encoding inference rules in RDF, where a 
rule may have a variable that is scoped by the rule; e.g.

    Dog(?x) -> Animal(?x)

Originally, I was thinking that, when encoding this in RDF the variable 
represented by ?x must somehow be scoped within the RDF.  But when I 
started looking at candidate RDF encodings this need for scoping just melts 
away:  the variable is represented by a new, unique resource:  that 
resource has global scope (and, hence, if it has a URI it is one that is 
not shared by any other resource).  The only place where the concept of 
scope is needed is in the original expression.  Some other expression; e.g.

    Cat(?x) -> Animal(?x)

Has a different scope for its ?x, but the resource that represents the 
variable in the encoding of this is a different resource than the one that 
represents ?x in the previous example.

 From this exercise, I tentatively suggest that the scope of any resource 
(node) is global -- the entire universe of discourse.

(I'm trying to be clear that this is an encoding of inference rules in RDF, 
not an attempt to make inference rules part of RDF.)

#g



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Graham Klyne                    Baltimore Technologies
Strategic Research              Content Security Group
<Graham.Klyne@Baltimore.com>    <http://www.mimesweeper.com>
                                 <http://www.baltimore.com>
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Received on Wednesday, 25 July 2001 12:22:05 EDT

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