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Can a property not have a uriref?

From: Murray Spork <m.spork@qut.edu.au>
Date: Tue, 17 Sep 2002 17:06:28 +1000
To: www-rdf-interest@w3.org
Message-id: <3D86D474.1010200@qut.edu.au>


Hi all,

I had assumed that all predicates must be named by some uriref - this 
seems obvious where a predicate appears in a simple s o p triple.

Then I thought of an example where you declare a resource of type 
"rdf:Property" without giving it a uriref - but even if this is valid 
RDF (would it be?) it wouldn't make sense cause you could never use it 
in a triple.

But today I thought of another possible counter example (where we are 
dealing with reification) that may actually make sense in some 
circumstances.

Can a property node that is part of a reification statement be an 
anonymous node? Below is a modification of the example given in the Primer:

<rdf:RDF
   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
   xmlns:a="http://description.org/schema/">
   <rdf:Description>
     <rdf:subject resource="http://www.w3.org/Home/Lassila" />
     <rdf:predicate>
     	<rdf:Description>
	    <rdf:type	 
resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#Property" />
     	<rdf:Description>
     <rdf:predicate>
     <rdf:object>Ora Lassila</rdf:object>
     <rdf:type 
resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#Statement" />
     <a:attributedTo>Ralph Swick</a:attributedTo>
   </rdf:Description>
</rdf:RDF>


IOW I am asserting that there exists some Statement that has a subject 
"http://www.w3.org/Home/Lassila", an object "Ora Lassila" and that has a 
  predicate which is some (unamed) Resource. Other properties could be 
attached to the Property bnode to further describe it without actually 
naming it.

Is this allowable/ make sense? If affirmative - then a property need not 
have a uriref?

BTW - "Property" and "predicate" appear to be used interchangeably - are 
they the same concept?

-- 
Murray Spork
Centre for Information Technology Innovation (CITI)
The Redcone Project
Queensland University of Technology, Brisbane, Australia
Phone: +61-7-3864-9488
Email: m.spork@qut.edu.au
Web: http://redcone.gbst.com/
Received on Tuesday, 17 September 2002 03:06:36 GMT

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