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Re: rdfs:class and rdfs:resource

From: David Menendez <zednenem@psualum.com>
Date: Thu, 8 May 2003 15:13:58 -0400
Message-Id: <a05111b00bae05aced03a@[]>
To: "Richard H. McCullough" <rhm@cdepot.net>, <www-rdf-interest@w3.org>, Dieter Köhler <dieter.koehler@philo.de>

At 4:02 AM -0700 2003-05-08, Richard H. McCullough wrote:
>The way I see it, every resource is EITHER an individual OR a class.

This is because you do not use the term "class" in the same way as 
RDF. The seeming paradox only arises when you try and make an 
instance of rdfs:Class correspond to your idea of what a "class" is.

Remember: according to the way the terms are used in RDF (and OWL), 
the set of resources belonging to a class is distinct from the class 

One can draw a parallel to Java here. Java has an Object class, which 
all objects are instances of, and a Class class, which all classes 
are instances of. Class is a subclass of Object, Object is an 
instance of Class, and Class is an instance of Object. However: 
Object is NOT a subclass of Class.

This is exactly the situation in RDFS:

	rdfs:Class rdfs:subClassOf rdfs:Resource .
	rdfs:Resource rdf:type rdfs:Class .
	rdfs:Class rdf:type rdf:Resource .

	rdfs:Resource rdfs:subClassOf rdfs:Class .
Dave Menendez - zednenem@psualum.com - http://www.eyrie.org/~zednenem/
Received on Thursday, 8 May 2003 15:13:19 UTC

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