From: Thomas Streicher <streicher@mathematik.tu-darmstadt.de>
To: Michael Shulman <shulman@math.uchicago.edu>
Cc: categories@mta.ca
Subject: Re: Not invariant but good
Date: Thu, 30 Sep 2010 13:34:21 +0200 [thread overview]
Message-ID: <20100930113421.GA23528@mathematik.tu-darmstadt.de> (raw)
In-Reply-To: <E1P160j-0001l3-I7@mlist.mta.ca>
> However, in the absence of the axiom of choice, the naive definition
> of "functor" is not very well-behaved; it's better to use "anafunctors,"
Nothing against anafunctors but it is an exaggeration to say that in absence
of choice the usual notion of functor is not well-behaved. One just loses that
full and faithful and essential surjective entails equivalence. That's like
abandoning the notion of surjective map in case we can't split them all.
Thomas
[For admin and other information see: http://www.mta.ca/~cat-dist/ ]
next prev parent reply other threads:[~2010-09-30 11:34 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-24 15:44 subculture Eduardo J. Dubuc
2010-09-25 0:38 ` subculture Ruadhai
2010-09-25 23:10 ` RE : categories: subculture Joyal, André
2010-09-26 2:43 ` subculture David Leduc
2010-09-26 3:19 ` subculture Fred Linton
[not found] ` <AANLkTikJoHkO2M_3hnrQqqFq2_N2T9i6KF2DRFbHTujP@mail.gmail.com>
2010-09-26 3:43 ` subculture Eduardo J. Dubuc
2010-09-25 4:01 ` Not invariant but good Joyal, André
[not found] ` <B3C24EA955FF0C4EA14658997CD3E25E370F59BE@CAHIER.gst.uqam.ca>
2010-09-26 3:29 ` John Baez
2010-09-27 2:54 ` Peter Selinger
2010-09-27 15:55 ` RE : categories: " Joyal, André
2010-09-28 2:10 ` RE : " John Baez
2010-09-29 18:05 ` no joke Joyal, André
2010-09-30 2:53 ` John Baez
2010-09-28 10:18 ` RE : categories: Re: Not invariant but good Thomas Streicher
2010-09-29 21:25 ` Michael Shulman
2010-09-30 3:07 ` Richard Garner
2010-09-30 11:11 ` Thomas Streicher
2010-09-30 19:39 ` Michael Shulman
2010-09-30 11:34 ` Thomas Streicher [this message]
[not found] ` <20101001092434.GA9359@mathematik.tu-darmstadt.de>
2010-10-03 22:10 ` Michael Shulman
2010-09-27 5:36 John Baez
2010-09-28 23:11 ` Michael Shulman
2010-10-01 12:36 Thomas Streicher
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