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Re: Thing and Class

From: Richard H. McCullough <rhm@pioneerca.com>
Date: Thu, 28 Aug 2008 07:04:33 -0700
Message-ID: <38963A06455C454EA8C6D7E6DA48A718@rhm8200>
To: "David Price" <david.price@eurostep.com>, "James Leigh" <james-nospam@leighnet.ca>
Cc: "Semantic Web at W3C" <semantic-web@w3.org>, "KR-language" <KR-language@YahooGroups.com>, "cyclify austin" <cyclify-austin@yahoogroups.com>

RE: Thing and ClassDavid
I don't know much about the OWL DL and nothing about ISO 15926.
Perhaps you could explain a little of them to me/us?

I don't think your statements 1) and 2) are correct.

1) A "Class" is not a set of things.  It is a strange sort
of group.  If it is a "plural" class, e.g. "dogs", then
it may be considered to be a set.  But if it is a "single"
class, e.g. "dog", then it may be considered to be an
enumeration (OneOf).

BTW, in mKR I use quantifiers to talk about the properties
of this strange group. "all dog" is the set, and "any dog"
is the enumeration (number = one), and "some dog" (number
= two or more), and "a dog" (number = one), and "the dog"
(number = one).

2) Classes are not members of Thing (Class type Thing).
They are subclasses of Thing (Class subClassOf Thing).

Dick McCullough
Ayn Rand do speak od mKR done;
mKE do enhance od Real Intelligence done;
knowledge := man do identify od existent done;
knowledge haspart proposition list;
http://mKRmKE.org/

  ----- Original Message ----- 
  From: David Price
  To: James Leigh ; Richard H. McCullough
  Cc: Semantic Web at W3C
  Sent: Thursday, August 28, 2008 2:30 AM
  Subject: RE: Thing and Class


  I think James Leigh's interpretation is flawed.

  1) It confuses "classification" (a statement that is a relationship 
between a class and a member) with "Class" (a set of things).

  2) It seems to miss the fact (at least in some statements) that Classes 
can also be Individuals (i.e. Classes are also members of the class Thing). 
All Individual means is "member of class". It is true that some Individuals 
are not classes (E.g. I am not a Class) but that does not mean no Classes 
are Individuals.

  This mis-interpretation is understandable given OWL DL being defined wrt 
set theory, not metaphysics. Since OWL DL, the language, says nothing about 
levels of abstraction being modeled, it cannot say whether any Individual is 
also a Class or not. As someone pointed out earlier, ISO 15926 Lifecycle 
integration schema tries to make this clear by defining Possible Individual 
as being something with a 4D extent and as being disjoint with Class.

  Cheers,
  David

  -----Original Message-----
  From: semantic-web-request@w3.org on behalf of James Leigh
  Sent: Thu 2008-08-28 03:30
  To: Richard H. McCullough
  Cc: Semantic Web at W3C
  Subject: Re: Thing and Class


  Hi Richard et al.

  Here is an informal interpretation of some of the spec written in plain
  English.

  Class stands for classification.
  We use Class to classify things.
  Class is a set of Things.
  "I am a Human" - I just classified myself as Human (I hope I'm right).
  "I am a Thing" - that is true for everything.
  Human is a classification of all people.
  Thing is a classification of all things.
  Every Human is a Thing. Therefore Thing is a super set of Human.
  Is Human a Thing? No! its a Class!
  Everything Thing is an individual.
  Human is not an individual, it is a classification of individuals.
  Thing is not an individual, it is a classification of individuals.
  Can we classify Classes? Yes we can! Human is a classification - I just
  classified Human as a classification.
  Human is a Class.
  Thing is a Class.
  Are all Things Classes? No! I am a Thing, but I am not a classification.
  Is Thing the same as Class? No! Human is not a Thing, but Human is a
  Class.

  Hope this helps,
  James
Received on Thursday, 28 August 2008 14:09:20 GMT

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