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  • To: xml-dev@l...
  • Subject: Re: many-to-many
  • From: John Cowan <jcowan@r...>
  • Date: Sun, 26 Jan 2003 22:22:44 -0500 (EST)

I accidentally failed to send this to the list:

"Emmanuil Batsis (Manos)" scripsit:

> The usability of anonymous nodes can be overrated as they don't have a 
> URI serving as a global unique identifier (and potentialy locator) for 
> them.

Indeed.  One would have to impose a higher-order rule that says "two b-nodes
with identical subjectIndicator properties are to be treated as identical",
as indeed they do in the TM world.

> Using "predications linking them to suitable subject-indicating URIs" 
> sounds cumbersome. Using actual resources provides this functionality in 
> a more uniform way. 

Sure, it's convenient to identify Shakespeare with his picture.  Unfortunately
it leads to nonsensical conclusions like "An English playwright has a height
of 160 pixels."

(end of original)

Manos then replied (copied here by permission):

> Ah, I see what your intended use of anonymous nodes originated from. The 
> situation you describe is a (quite common) human error in understanding 
> and applying the semantics of RDF. Your use-case is also a good place to 
> distinguish between retreivable and non-retreivable resources.

This is exactly isomorphic to the TM distinction between resource references
and subject-indicating references.

> The right thing to do would be to use a non-retreivable scheme URI 
> (perhaps a URN?) (or an rdf:ID) to denote Shakespeare, as one cannot 
> simply download him. His picture should be mentioned as just that, not 
> as the person itself. Anonymous nodes are not needed to avoid confusion:
> 
> <rdf:Description rdf:about="nonRetreivable://Persona/Shakespeare">
>     <foo:picture rdf:resource="http://URL/to/pic"/>
> </rdf:Description>

The rdf:ID to which you refer is the b-node/anonymous node I was talking
about in the first place.

-- 
Evolutionary psychology is the theory           John Cowan
that men are nothing but horn-dogs,             http://www.ccil.org/~cowan
and that women only want them for their money.  http://www.reutershealth.com
        --Susan McCarthy (adapted)              jcowan@r...



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