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

From: Jim Hendler <hendler@cs.rpi.edu>
Date: Thu, 13 Dec 2007 16:41:44 -0500
Message-Id: <50EBC962-3182-4856-B42F-8866E9F90528@cs.rpi.edu>
Cc: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>, public-owl-wg@w3.org
To: Alan Ruttenberg <alanruttenberg@gmail.com>
We don't document features outside DL in OWL 1.0?  The reference  
document does exactly that - we didn't provide semantic discussion of  
all possible features, but every vocabulary term in OWL was discussed  
w/respect to DL and Full.   Grabbing one at random:

---- from Owl ref 4,1
The property owl:equivalentClass is used to indicate that two classes  
have precisely the same instances. Note that in OWL DL, classes  
simply denote sets of individuals, and are not individuals  
themselves. In OWL Full, however, we can use owl:sameAs between two  
classes to indicate that they are identical in every way.

so we did indeed document the differences.  There are things one can  
do in OWL Full that we didn't document, but that was mainly because  
we didn't think of them, not that we were not trying to document them.

On Dec 13, 2007, at 11:08 AM, Alan Ruttenberg wrote:

> This was discussed at TC. Action is on me an Ian to draft wording  
> explaining closing/relation to OWL Full.
> The gist is that it will never be in DL because of undecidability.  
> It will be in OWL Full by virtue of syntax. Following precedent of  
> OWL 1.0 we don't specifically document features outside OWL DL,  
> though they may have semantics given in full, and that it will be  
> at the discretion of the OWL Full semantics document editor to  
> decide whether they want to provide a specific semantics for the form.
> -Alan
> 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

Received on Thursday, 13 December 2007 21:41:56 UTC

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