RE: PROPOSAL to *close* (not postpone) ISSUE-83

I agree to close this issue modulo Jim's suggestion of documenting that these
features are allowed in Full
and also an example of how an OWL Full specification expressing the property
chain axion (R o S => S o R)
would look like.
 
Thanks,
 
---Vipul


________________________________

	From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org]
On Behalf Of Jim Hendler
	Sent: Thursday, December 13, 2007 10:47 AM
	To: Peter F. Patel-Schneider
	Cc: public-owl-wg@w3.org
	Subject: Re: PROPOSAL to *close* (not postpone) ISSUE-83
	
	
	WHile I don't actually disagree with Peter on this one, I do think there
are several things incumbent on us in these issue 
	 1  - we need to document that these features are allowed in Full
	 2 -  close vs. postpone may, in some cases, depend on whether we think
in the future their might be a solution - inverseFunctional datatypes, for
example, have led to "key"s which we are at least considering for 1.1 - so if in
some cases, and this might or might not be one, we think there might be limited
solutions that would be decidable, we should consider postponing with a note to
that effect.  From the point of view of this WG, close vs. postpone has little
difference, but from the pov of a future WG, this shows them there might be
interest in the issue if a technical solution can be found or if at some future
date a WG decides to stop worrying so much about keeping OWL Full and OWL DL as
tightly coupled as they are now.
	 -JH



	On Dec 13, 2007, at 10:05 AM, Peter F. Patel-Schneider wrote:



		Issue-83 asks for property chains on both sides of subproperty
axioms.

		As pointed out by Uli Sattler 
	
http://lists.w3.org/Archives/Public/public-owl-wg/2007Nov/0600.html
		this makes OWL 1.1 undecidable.

		Contrary to what Ian Horrocks says
	
http://lists.w3.org/Archives/Public/public-owl-wg/2007Dec/0012.html
		this feature would automatically be in an OWL
		Full version because there would have to be in OWL Full a
semantic
		treatment of property chains and then there would be no way of
excluding
		them from both ends of a rdfs:subPropertyOf axiom.

		I therefore propose that we CLOSE ISSUE-83 without doing
anything on the
		twin grounds that it both compromises decidability in OWL 1.1
and is not
		handled by tools, and that there is nothing special that needs
to be
		done in OWL Full.

		Peter F. Patel-Schneider
		Bell Labs Research

		PS:  If the "undecidability" was not present above then it would
be
		     reasonable to POSTPONE the issue.  However, undecidability
		     conflicts with the goals of OWL DL (and OWL 1.1) and thus I
		     strongly believe that CLOSURE is much more appropriate.



	
	"If we knew what we were doing, it wouldn't be called research, would
it?." - Albert Einstein

	Prof James Hendler http://www.cs.rpi.edu/~hendler
	Tetherless World Constellation Chair
	Computer Science Dept
	Rensselaer Polytechnic Institute, Troy NY 12180






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