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Fwd: aboutEach and reification

From: Aaron Swartz <me@aaronsw.com>
Date: Fri, 29 Jun 2001 17:41:03 -0500
To: "'www-Rdf-Comments@W3.Org'" <www-rdf-comments@w3.org>
Message-Id: <20010629224105.PAPU22639.femail18.sdc1.sfba.home.com@localhost>
On RDF-Interest, Jeremy brought up some RDF examples that look 
like they should be resolved by the spec/Working Group. I 
believe that these cases reveal an issue with the spec, and that 
it should probably be resolved by the Working Group. Feedback is 
appreciated.

Thanks,
  - Aaron

 From: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Date: Tue Jun 26, 2001  11:06:17  AM US/Central
To: <www-rdf-interest@w3.org>
Subject: aboutEach and reification



I, foolishly, am looking at writing another RDF parser. (ARP?).

In my design stages I stumbled across this little teaser:

what statements does the following correspond:

<rdf:RDF xmlns:rdf="..." xmlns:a="...">
   <rdf:Description aboutEach="#self" bagId="self">
     <a:prop>value</a:prop>
   </rdf:Description>
</rdf:RDF>

[The ... are uri's]

or we can make it a little richer with:

<rdf:RDF xmlns:rdf="..." xmlns:a="...">
   <rdf:Description aboutEach="#self" bagId="self">
     <a:prop>value</a:prop>
   </rdf:Description>
   <rdf:Description about="#self">
     <rdf:_1 rdf:resource="http://bertrand-russell-lives.org/">
   </rdf:Description>
</rdf:RDF>

One reading of M&S would say that this second description has an 
infinite
model.
"#self" is a bag, it includes at least one member,
http://bertrand-russell-lives.org/

This resource is hence one of the distributive referent of 
a:prop="value"
and so we add the statement model, and add its reification to the bag
"#self". The reification is anonymous, and since it is in 
"#self" it is one
of the distributive referent and so ...
ad infinitum.

A different reading is suggested by naming the reification of a 
statement
with a distributive referent.

e.g.
<rdf:RDF xmlns:rdf="..." xmlns:a="...">
   <rdf:Description aboutEach="#other" bagId="self">
     <a:prop ID="ex">value</a:prop>
   </rdf:Description>
   <rdf:Bag ID="other>
     <rdf:li rdf:resource="http://bertrand-russell-lives.org/a1"/>
     <rdf:li rdf:resource="http://bertrand-russell-lives.org/a2"/>
   </rdf:Bag>
</rdf:RDF>

Then do we have two rdf:subject's for the reification "#ex".
the bag "#self" can have only one member with uri "#ex" is there 
a second
member corresponding to the second member of "#other" or is 
there just one
member corresponding to the single statement "#ex" in the description.

We could read reification within an aboutEach as generating one 
resource per
property in the description, with one subject for each subject in the
distributive referent.


Enjoy ...

Jeremy
Received on Friday, 29 June 2001 18:41:12 GMT

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