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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: <>
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.)


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

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