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Re: P.S. re: two senses of Class (RDF vocabulary definiitions)

From: Richard H. McCullough <rhm@cdepot.net>
Date: Tue, 19 Nov 2002 23:34:09 -0800
Message-ID: <001901c29067$385522d0$bd7ba8c0@rhm8200>
To: "David Menendez" <zednenem@psualum.com>, "RDF-Interest" <www-rdf-interest@w3.org>
Re: P.S. re: two senses of Class (RDF vocabulary definDavid Menendez and Leonid Ototsky both inform me that an Individual can be a Class.
That is absolutely false.  
Here are the definitions from the theory of epistemology,
paraphrased to match the context of our current discussion.

    An individual is a single concrete existent.

    A class is an abstract group of two or more similar individuals.
Dick McCullough 
knowledge := man do identify od existent done
knowledge haspart list of proposition

  ----- Original Message ----- 
  From: David Menendez 
  To: RDF-Interest 
  Sent: Tuesday, November 19, 2002 10:52 PM
  Subject: Re: P.S. re: two senses of Class (RDF vocabulary definiitions)

  At 10:16 PM -0800 2002-11-19, Richard H. McCullough wrote:
    I had forgotten about the other problem with type, e.g.

        John Doe  type  person


        John Doe  individualOf  person


        John Doe  subClassOf  person

  I'm not sure what problem you're seeing.

  In RDF(S), the statements
    eg:john_doe rdf:type eg:Person.
    eg:john_doe rdf:subClassOf eg:Person.
  are entirely independent and mean different things.

  My understanding of RDF-MT is that the first statement means "I(eg:john_doe) is a member of ICEXT(I(eg:Person))" while the second means "ICEXT(I(eg:john_doe)) is a subset of ICEXT(I(eg:Person))". These are distinct assertions, and either can be true without the other being true.

  (I(x) is the interpretation of x, and ICEXT(y) is the set of all things belonging to the class y.)

  If I say
    eg:Dog rdfs:subClassOf eg:Mammal.
  I am not implying
    eg:Dog rdf:type eg:Mammal.
  because that would mean that the class "Dog" is a mammal, which it is not. Individual dogs are mammals, but the set of all dogs is a set.
Dave Menendez - zednenem@psualum.com - http://www.eyrie.org/~zednenem/
Received on Wednesday, 20 November 2002 02:34:21 UTC

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