vocabulary for traditional sets

With the model theory and such,
it's becoming more clear what rdfs:Class and rdf:type
mean... in particular, it's not illegal to say

	_:A rdfs:subClassOf _:B.
	_:B rdfs:subClassOf _:A.

but it doesn't mean that A=B; i.e. if you know
	_:A my:color "blue".
you can't conclude
	_:B my:color "blue.

But I would like to be able to say that
X and Y are sets, which allows you to conclude,
from the fact that their extensions/membership
are  the same that they are identical.

So I propose
	rdfs:Set rdfs:subClassOf rdfs:Class.

	this log:forAll :x, :y.
	{ :x a rdfs:Set.
	:y a rdfs:Set.
	:x rdfs:subClassOf :y.
	:y rdfs:subClassOf :x.
	} log:implies {
	:x ont:equivalentTo :y

hmm... need ont:equivalentTo to say what I mean.
Maybe this is more for the WebOnt WG. But anyway...
whever it belongs, it's a comment based on
experience with RDF, so I'm sending it to
www-rdf-comments now because I keep thinking
of it and not having anything written down...

Dan Connolly, W3C http://www.w3.org/People/Connolly/

Received on Tuesday, 6 November 2001 05:02:28 UTC