W3C home > Mailing lists > Public > www-rdf-interest@w3.org > November 2002

Re: RDF vocabulary definitions

From: Richard H. McCullough <rhm@cdepot.net>
Date: Thu, 21 Nov 2002 12:09:58 -0800
Message-ID: <004b01c29199$f7babf30$bd7ba8c0@rhm8200>
To: "David Menendez" <zednenem@psualum.com>, "Brian McBride" <bwm@hplb.hpl.hp.com>
Cc: "RDF-Interest" <www-rdf-interest@w3.org>
This is where I draw the line in the sand.
I am definitely saying that the concept of RDF Class is wrong.
I'll try to answer each of your questions.  If I haven't answered some to your satisfaction, speak up.

1. a number is a class.
"two" is the abstraction of "two apples", "two oranges", "two people", etc.

2. an empty class is nonexistent.
if the class has no members, it is a "floating abstraction", a "contradiction"
it does not exist
it has no properties
how many ways can I say it?

3. a class with 1 member is a waste of time and effort
For example, if I were to define a Class containing only "Dick McCullough", what have I gained?
I now have an Individual "Dick McCullough", and a class "Dick McCullough" with the same meaning.
The only thing I have done is add an extra Class to clutter up my mental bookkeeping.
The same principle applies to integrating subclasses into wider classes, or dividing classes into narrower subclasses.
============ 
Dick McCullough 
knowledge := man do identify od existent done
knowledge haspart list of proposition

  ----- Original Message ----- 
  From: Brian McBride 
  To: Richard H. McCullough ; David Menendez 
  Cc: RDF-Interest 
  Sent: Thursday, November 21, 2002 9:49 AM
  Subject: Re: RDF vocabulary definitions


  At 08:44 21/11/2002 -0800, Richard H. McCullough wrote:
  >It was my impression that "instance" was deprecated, to be replaced by 
  >"individual".
  >For example, see 
  ><http://www.w3.org/TR/2002/WD-owl-features-20020729/>http://www.w3.org/TR/2002/WD-owl-features-20020729/ 
  >
  >
  >However, looking at the OWL document again, I see it uses both terms:
  >     "Individuals may described as an instance of a Class ..."

  If we are talking about RDF, please can we use RDF's terminology.  It might 
  be a good idea to note any confusion of teminilogy to both WG's comment 
  lists though.

  [...]

  >
  >Here's a simple definition of "individual" and "class".
  >An individual is a single concrete existent.

  I'd have a little trouble with that I think.  The real number Pi is a 
  resource.  Is that a single *concrete* existent?  The set of real numbers 
  is a resource - is that a *single* concrete existent?  The set of rational 
  numbers is a resource - is that  a single concrete *existent*.

  >A class is an abstract group (a mental integration) of two or more similar 
  >individuals.

  RDFS classes can be empty or have just one member and those members do not 
  have to be individuals by your definition.

  I'm not quite sure what you are trying to say here.  Are you saying that 
  RDFS's use of the term class is different to the way you use the term?  If 
  so, fine, I agree.  It also different to the way that Java uses the term, 
  so I'm not too bothered so long as we are all clear which variant we 
  are  discussing at any one time.  If you are saying therefore its wrong, 
  then that is another matter.

  Brian
Received on Thursday, 21 November 2002 15:09:59 GMT

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