Thanks, Doug. No, I was just using the usual example that Illustrates the
difference between intension and extension. i.e., the intension is a
description (function from possible worlds to extensions) that can be realized
by particular instances (have a specific extension). "The man in the corner
with the hat" is "John" here in this room, but would pick out "Adam" in another
context/world. I.e., the usual argument for intensional logics in philosophy of
language/NL semantics. (01)
Simple cases are perhaps indexicals such as "now" and "here", which have common
intensions, but different extensions. But even here you get into thorny issues,
which I'll not go into. (02)
Thanks,
Leo (03)
-----Original Message-----
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of doug foxvog
Sent: Monday, July 09, 2012 5:03 PM
To: [ontolog-forum]
Subject: Re: [ontolog-forum] Truth (04)
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. (05)
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. (06)
As such, the extent of EveningStar and MorningStar is temporally
dependent. There is no CalendarDay during which they have the same
extension. (07)
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. (08)
-- doug foxvog (09)
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