categories: Re: the alpha of Omega

[Colin McLarty <cxm7@po.cwru.edu>]

[note from moderator: apologies to Colin for delayed posting...Bob]

"Dr. P.T. Johnstone" <P.T.Johnstone@dpmms.cam.ac.uk> wrote of $\Omega$ as
subobject classifier:

>I seem to recall being told that it occurs somewhere in the
>original (mimeographed) version of SGA4 (as an interesting
>example of a sheaf on a site), and that Lawvere and Tierney
>borrowed the notation that Grothendieck et al. had used for it.
>However, I've never been able to find it there myself; I'm
>pretty sure it's not in the revised version published in
>Springer Lecture Notes.

	I have heard that too. And I am sure it is not in the published SGA4. I
have one mimeographed version in my office. Omega does not occur there the
sections on topologies, but next week I will look to see if it occurs as an
example of a sheaf--unless someone who knows writes in sooner.

best, Colin
_________________________________________
Dialectic, the purest part of philosophy, hovers attentively over
mathematics, encompasses its whole development, and of itself contributes
to the special sciences their various perfecting, critical, and
intellective powers--the powers, I mean, of analysis, division, definition,
and demonstration. 

--Proclus, ca. 460 AD, A COMMENTARY ON THE FIRST BOOK OF EUCLID'S ELEMENTS