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FAQ: stratified class hierarchies vs. RDFS

From: Dan Connolly <connolly@w3.org>
Date: 20 Jun 2002 13:35:53 -0500
To: www-rdf-comments@w3.org
Cc: Tim Berners-Lee <timbl@w3.org>, "R.V.Guha" <guha@guha.com>
Message-Id: <1024598155.26130.1506.camel@dirk>

The fact that rdfs:Class is an rdfs:Class
looks odd to lots of people:

  - folks familiar with ZF set theory
  freak out, because it looks like a
  set is an element of itself.
	(the RDF model theory treats
	this artfully, I think.)

  - folks that are used to stratified
  class metamodels find it odd too.

It came up again today.

Please add something about this to the RDF FAQ
or the RDF primer or something.

I think the reason that RDFS is this way
is the "anybody can say anything about anything"
principle... a stratified approach disallows
cycles, which are a naturally occuring phenomenon
in the web.

Hmm... I don't think I put that very well.

Tim, maybe you could try your hand at explaining
how stratified systems are not web-like? Guha?

Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Thursday, 20 June 2002 14:35:42 UTC

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