From: "John Baez" <baez@math.ucr.edu>
To: categories@mta.ca (categories)
Subject: regular, geometric, and coherent categories
Date: Fri, 24 Oct 2003 18:08:47 -0700 (PDT) [thread overview]
Message-ID: <200310250108.h9P18lo20637@math-cl-n01.ucr.edu> (raw)
I wrote:
> Here's some stuff I think I know. I know the definitions of
> the above concepts, as long as I have the book open to the
> right page... but I left it at home, so these could be wrong!
Some were.
> Cartesian categories have finite limits. Regular categories
> are cartesian categories with regular epi/mono factorizations,
> which must be stable under pullbacks.
Fine.
> Geometric categories are
> regular categories admitting arbitrary unions of subobjects,
> which must be stable under pullbacks. Coherent categories
> are geometric categories where pullback of subobjects has a
> right adjoint (which plays the role of "for all").
These were mixed up.
next reply other threads:[~2003-10-25 1:08 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-10-25 1:08 John Baez [this message]
-- strict thread matches above, loose matches on Subject: below --
2003-10-23 23:33 regular, geometric " John Baez
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