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Re: RDF vocabulary definitions

From: Richard H. McCullough <rhm@cdepot.net>
Date: Tue, 19 Nov 2002 09:17:28 -0800
Message-ID: <004d01c28fef$8a2d1040$bd7ba8c0@rhm8200>
To: "Jeen Broekstra" <jeen.broekstra@aidministrator.nl>, "Manne Miettinen" <manne.miettinen@csc.fi>
Cc: <www-rdf-interest@w3.org>
The two triples have the same meaning; either one implies the other.
<_:MyClass> <rdf:type> <rdfs:Class>
<_:MyClass> <rdfs:subClassOf> <rdfs:Class>
============ 
Dick McCullough 
knowledge := man do identify od existent done
knowledge haspart list of proposition

  ----- Original Message ----- 
  From: Jeen Broekstra 
  To: Manne Miettinen 
  Cc: www-rdf-interest@w3.org 
  Sent: Tuesday, November 19, 2002 7:23 AM
  Subject: Re: RDF vocabulary definitions



  Manne Miettinen wrote:

   > Here's a beginners' question, please tolerate...
   >
   > I would like to know what is the difference between rdfs:Class and
   > rdf:Description when defining a class in my own RDF vocabulary. Are
   > the following two class definitions equivalent?
   >
   > <rdfs:Class rdf:ID="MyClass">
   >   <rdfs:subClassOf
   >    rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
   > </rdfs:Class>
   >
   > <rdf:Description rdf:ID="MyClass">
   >   <rdf:type
   >    rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
   > </rdf:Description>

  No, these are not equivalent. It becomes easier when you try to take
  into account which triples an RDF parser would produce from the above
  syntax.

  The first one produces these two triples:

  <_:MyClass> <rdf:type> <rdfs:Class>
  <_:MyClass> <rdfs:subClassOf> <rdfs:Class>

  The second one produces just this one triple:

  <_:MyClass> <rdf:type> <rdfs:Class>

  As an aside, I'm not quite sure why you would want the subClassOf
  statement in the first example, it's not forbidden but certainly awkward
  modeling.

  Going back to XML syntax, the <rdfs:Class> element is just a shorthand
  notation for stating that the description being given is of type
  rdfs:Class. So the following two definitions _are_ equivalent:

  <rdfs:Class rdf:ID="MyClass"/>

  <rdf:Description rdf:ID="MyClass">
      <rdf:type rdf:resource="http://www.w3.org/2000/01/rdf-schema#Class"/>
  </rdf:Description>

  Hope that helps.

  Best regards,

  Jeen
  -- 
  jeen.broekstra@aidministrator.nl
  aidministrator nederland bv - http://www.aidministrator.nl/
  julianaplein 14b, 3817 cs amersfoort, the netherlands
  tel. +31-(0)33-4659987, fax. +31-(0)33-4659987
Received on Tuesday, 19 November 2002 12:17:30 GMT

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