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Re: subclasses (RDF vocabulary definitions)

From: Richard H. McCullough <rhm@cdepot.net>
Date: Thu, 21 Nov 2002 14:27:26 -0800
Message-ID: <003201c291ad$2c462740$bd7ba8c0@rhm8200>
To: <www-rdf-interest@w3.org>, "David Menendez" <zednenem@psualum.com>, "Brian McBride" <bwm@hplb.hpl.hp.com>
Brian said:

  [[ll classes are subclasses of themselves.
<<this is true, but RDF Schema should use proper subsets instead of subsets.
Using subsets logically permits such absurdities as: the set of all men is
identical to the set of all animals.>>]]

I'm intrigued by that one.  We have a major flaw if that is true.  Care to 
explain?

I'm going to use some KR notation here because I think you will find it easier to understand.

Here's the notation
"is":  man  is  animal          sets are identical
"iss":  man  iss  animal       man is proper subset of animal
"iss*": man  iss*  animal      man is subset of animal

iss is the main property used in KR
iss* is the rdfs:subClassOf property, and its meaning is that
    either man is animal
         or man iss animal

and it's also the source of "bragging" about a class being a subclass of itself, i.e.,
    man iss* man
    animal iss* animal
============ 
Dick McCullough 
knowledge := man do identify od existent done
knowledge haspart list of proposition
Received on Thursday, 21 November 2002 17:27:27 GMT

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