Re: RDF vocabulary definitions

At the time MyClass was defined -- simply declared to be a Class -- no extension was given, so technically the extension of MyClass is the empty set.  I assume the author will provide additional statements to specify the individuals of MyClass.

P.S. Note that in a subsequent email I corrected my statement to read as follows:
The rdf-mt document http://www.w3.org/TR/2002/WD-rdf-mt-20021112/
> says in Appendix A, "RDF Axioms":
>     rdf:type(?x,?y)  iff  ?y(?x)
> The triple translation is
>     <?x> <rdf:type> <?y>  iff  <?x> <rdfs:subClassOf> <?y>  or  <?x> <rhm:individualOf> <?y>
> The KR translation is
>     $x has rdf:type = ?y  iff  $x isa* $y
============ 
Dick McCullough 
knowledge := man do identify od existent done
knowledge haspart list of proposition

  ----- Original Message ----- 
  From: Jeen Broekstra 
  To: Richard H. McCullough 
  Cc: Jon Hanna ; www-rdf-interest@w3.org 
  Sent: Tuesday, November 19, 2002 11:43 AM
  Subject: Re: RDF vocabulary definitions



  Richard H. McCullough wrote:

  > The rdf-mt document http://www.w3.org/TR/2002/WD-rdf-mt-20021112/
  > says in Appendix A, "RDF Axioms":
  >     rdf:type(?x,?y)  iff  ?y(?x)
  > The triple translation is
  >     <?x> <rdf:type> <?y>  iff  <?x> <rdfs:subClassOf> <?y>
  > The KR translation is
  >     $x has type = $y  iff  $x isa* $y

  Looking at section 3.3 of the MT, you seem to be correct, though this is
  not reflected in the RDFS entailment rules in section 4.

  Section 3.3 (RDFS Interpretations):

     <x,y> is in IEXT(I(rdfs:subClassOf)) if and only if x and y are in IC
     and ICEXT(x) is a subset of ICEXT(y)

  Substituting:

     <MyClass, rdfs:Class> is in IEXT(I(rdfs:subclassOf)) if and only if
     1.  MyClass and rdfs:Class are in IC
           and
     2.  ICEXT(MyClass) is a subset of ICEXT(rdfs:Class)

  Condition 1 is trivially met. Condition 2 is met because ICEXT(MyClass) 
  is the empty set.

  It's late and I'm tired. Am I overlooking something, or is this a bug?

  Best regards,

  Jeen