On 7/8/2012 2:46 PM, Obrst, Leo J. wrote:
> So if I understand your statements correctly, two OWL classes EveningStar
> and MorningStar will be equal if their extensions are the same, i.e., {venus},
> or: EveningStar = MorningStar. (01)
I cannot believe that Peter Patel-Schneider and Ian Horrocks would make
such an obvious blunder. Just look at their definitions: (02)
http://www.w3.org/TR/owl-semantics/direct.html (03)
> And that this holds of OWL-DL, but not of OWL-Full, correct?
> In OWL-Full, EveningStar \= MorningStar, even if they have the same
> extension (apparently because OWL-Full allows classes to be instances, and
> that therefore, one does not know if the extension of a given class includes
> the instance or the class). (04)
The question whether classes can be instances of classes is irrelevant.
Common Logic allows relations to be arguments of relations. That option
does not have the slightest effect on the distinction between intensions
and extensions. (05)
If the W3C had just adopted LBase semantics (and therefore CL model
theory) all these questions would be completely clear. The people who
try to replace logic with something "simpler" always create problems
that are immensely more complex than anything they hoped to avoid. (06)
The W3C should have declared that anybody who could not pass a simple
test on FOL would be disqualified from voting. Every professional group
has minimum standards for membership *and* voting. You cannot allow
incompetents to vote on technical issues. (07)
John (08)
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