From: David Yetter <dyetter@math.ksu.edu>
To: André <joyal.andre@uqam.ca>
Cc: "John Baez" <baez@math.ucr.edu>, "categories" <categories@mta.ca>
Subject: Re: are fibrations evil?
Date: Sun, 19 Sep 2010 09:57:24 -0500 [thread overview]
Message-ID: <E1Oxikp-0005Lp-4A@mlist.mta.ca> (raw)
In-Reply-To: <E1OxKoA-0004wT-Jd@mlist.mta.ca>
Dear Andre:
Brevity is the usual reason for introducing new terminology.
And, ultimately there is a need, as mathematics would grind
to a halt if one had to write out a phrase giving the content
of each concept whenever one wanted to talk about it.
One may object to the jocular use of a word with a moral
denotation as the name for a mathematical concept, but four
characters beats 28 characters (or 31 if one counts spaces).
It certainly seems desirable to have a brief name for either
"invariant under equivalence" or "not invariant under
equivalence".
Best Thoughts,
David Y.
On 18 Sep 2010, at 08:50, Joyal, André wrote:
> Dear John,
>
> A property is "evil" in your sense if it is
> not invariant under equivalences.
> Invariance under equivalence is a well
> established mathematical notion.
> I prefer to say that something is not
> invariant under equivalence than to say
> that it is "evil". There is no need to
> introduce a new terminology.
>
> Best,
> André
>
[For admin and other information see: http://www.mta.ca/~cat-dist/ ]
next prev parent reply other threads:[~2010-09-19 14:57 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-17 4:36 John Baez
2010-09-18 13:50 ` Joyal, André
2010-09-19 14:57 ` David Yetter [this message]
[not found] ` <F8DA87C6-CBED-44AE-B964-B766A95D8417@math.ksu.edu>
2010-09-19 18:21 ` Joyal, André
2010-09-20 17:04 ` Eduardo J. Dubuc
2010-09-20 16:59 ` Eduardo J. Dubuc
2010-09-22 2:52 ` Toby Bartels
[not found] ` <20100922025245.GA14958@ugcs.caltech.edu>
2010-09-22 18:56 ` Eduardo J. Dubuc
[not found] ` <4C9A5156.3010307@dm.uba.ar>
2010-09-22 21:06 ` Toby Bartels
-- strict thread matches above, loose matches on Subject: below --
2010-09-24 23:43 Fred E.J. Linton
2010-09-17 2:17 David Roberts
2010-09-15 11:43 Thomas Streicher
2010-09-16 0:28 ` Michael Shulman
2010-09-16 1:14 ` Peter LeFanu Lumsdaine
[not found] ` <AANLkTinosTZ2NQW9biPxiwpX9zPi5m=kwvA16nHjK=Xu@mail.gmail.com>
2010-09-16 9:47 ` Thomas Streicher
2010-09-16 10:00 ` Prof. Peter Johnstone
[not found] ` <alpine.LRH.2.00.1009161023190.12162@siskin.dpmms.cam.ac.uk>
2010-09-16 10:46 ` Thomas Streicher
2010-09-17 7:44 ` Toby Bartels
[not found] ` <20100916094755.GA19976@mathematik.tu-darmstadt.de>
2010-09-17 5:01 ` Michael Shulman
2010-09-18 13:48 ` Thomas Streicher
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