From: Peter Johnstone <ptj@dpmms.cam.ac.uk>
To: Categories mailing list <categories@mta.ca>
Subject: When is Fam(E) a topos?
Date: Mon, 24 Apr 2017 10:57:32 +0100 (BST) [thread overview]
Message-ID: <E1d2dqR-0007dL-Vh@mlist.mta.ca> (raw)
Others may have noticed a slight gap in what I wrote on Saturday,
concerning the difference between toposes with set-indexed
copowers and those with coproducts. If E has copowers then the
functor Delta exists, but to prove that Fam(E) is equivalent to
the topos obtained by glueing along it you need arbitrary
coproducts. In fact these are necessary for Fam(E) to be
cartesian closed; I now have a proof of this, but it's a bit
too complicated to write out in ASCII. I plan to write it up as
a short paper.
Peter Johnstone
[For admin and other information see: http://www.mta.ca/~cat-dist/ ]
next reply other threads:[~2017-04-24 9:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-24 9:57 Peter Johnstone [this message]
-- strict thread matches above, loose matches on Subject: below --
2017-04-19 9:23 when is Fam (E) " Thomas Streicher
2017-04-21 9:01 ` Thomas Streicher
2017-04-22 16:35 ` Peter Johnstone
[not found] ` <alpine.DEB.2.10.1704221719340.10704@siskin.dpmms.cam.ac.uk>
2017-04-23 8:52 ` Thomas Streicher
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