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'm not sure what your defined intension is of EveningStar and
MorningStar. If it is "the first/last star-like object to appear in the
evening/morning sky (if the sky is clear)", then the set of possible
extensions would be greater {venus, jupiter, sirius, ...} only one of
which would be the extent in a specific spatio-
temporal context. (02)
As such, the extent of EveningStar and MorningStar is temporally
dependent. There is no CalendarDay during which they have the same
extension. (03)
Under this definition, there is no equality (of extension) between
MorningStar
and EveningStar. If the intension is "objects that on some days would be
[Intension 1]", then they would have the same extension. (04)
-- doug foxvog (05)
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