RE: "Is a Property a Class" and other DAML questions

Perhaps the implication is coming from this statement in the DAML+OIL spec: 

<rdfs:Class rdf:ID="Property">
  <sameClassAs
rdf:resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#Property"/>
</rdfs:Class>

I am not an RDF(S) expert, but to me this says that a Property is a Class.
If this is not the case, what point am I missing?

- Lewis
___________________________________________
Lewis L Hart 
GRC International                           lhart@grci.com
1900 Gallows Rd.                  Voice (703)506-5938
Vienna, Va 22182                    Fax (703)556-4261


-----Original Message-----
From: Peter F. Patel-Schneider [mailto:pfps@research.bell-labs.com]
Sent: Monday, March 05, 2001 1:04 PM
To: cbalon@grci.com
Cc: www-rdf-logic@w3.org
Subject: Re: "Is a Property a Class" and other DAML questions


From: "Balon, Corey" <cbalon@grci.com>
Subject: "Is a Property a Class" and other DAML questions
Date: Mon, 5 Mar 2001 11:48:08 -0500 

> Just a few items that have been bothering me:
> 
> 1) Is a Property a Class?
> 	Can you put Properties in the places where Classes are allowed?
> 	(ex. PropA sameClassAs PropB)
> 2) Can something be both a Property and a Class?
> 	is daml:TransitiveProperty both a Property and a Class?
> 
> In some places such as http://www.daml.org/2000/12/daml+oil.daml
> the answers to the above seem to be "yes", however
> in others such as 3.1.3 of
> http://www.daml.org/2000/12/axiomatic-semantics.html,
> which says that "properties and classes are disjoint",
> the answers seem to be "no"

I'm not sure where you are seeing the implication that properties and
classes are not disjoint in the DAML spec.  It is true that some of the
DAML spec documents are neutral with respect to this question, but I don't
think that any actively mention objects that are both classes and
properties.  The only place where classes and properties are stated to be
disjoint is in the axiomatization, and the only reason for that is that
this comes from RDF (or RDFS).

(As an aside, I can't find where this disjointness requirement is in RDF or
RDFS.  If it isn't there, then the axiom in the DAML+OIL axiomatization
should be removed.)


Peter Patel-Schneider

Received on Wednesday, 7 March 2001 16:01:10 UTC