From: Vaughan Pratt <pratt@cs.stanford.edu>
To: categories@mta.ca
Subject: Is equality evil?
Date: Wed, 15 Sep 2010 22:14:19 -0700 [thread overview]
Message-ID: <E1OwQEy-0002cd-TZ@mlist.mta.ca> (raw)
In-Reply-To: <E1Ow1kx-0002Vi-3Z@mlist.mta.ca>
Theorem. Equality if and only if the diagonal.
Corollary. P(equality) <--> P(contraction)
(where the predicate P may be "Evil", "Nonlinear", "Sophomoric", etc)
In this context (as opposed to metric spaces, materials, and maternity
wards) contraction is the logical rule predicated on the idea that two
things with the same name are actually one. See Kripke and others on
the topic of Naming and Necessity.
Were Rosa Parks still around she would surely not judge equality evil.
[For admin and other information see: http://www.mta.ca/~cat-dist/ ]
next prev parent reply other threads:[~2010-09-16 5:14 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-15 11:43 are fibrations evil? Thomas Streicher
2010-09-16 0:28 ` Michael Shulman
2010-09-16 1:14 ` Peter LeFanu Lumsdaine
2010-09-16 5:14 ` Vaughan Pratt [this message]
2010-09-17 8:28 ` Is equality evil? Toby Bartels
2010-09-18 14:11 ` Thomas Streicher
2010-09-19 20:30 ` Erik Palmgren
2010-09-24 12:50 ` Bas Spitters
[not found] ` <20100918141110.GC9467@mathematik.tu-darmstadt.de>
2010-09-22 4:00 ` Toby Bartels
2010-09-25 16:18 ` Michael Shulman
[not found] ` <20100922040041.GB14958@ugcs.caltech.edu>
2010-09-22 10:27 ` Thomas Streicher
2010-09-16 8:50 ` why it matters that fibrations are "evil" Thomas Streicher
[not found] ` <AANLkTinosTZ2NQW9biPxiwpX9zPi5m=kwvA16nHjK=Xu@mail.gmail.com>
2010-09-16 9:47 ` are fibrations evil? 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
[not found] ` <20100918134829.GB9467@mathematik.tu-darmstadt.de>
2010-09-20 16:25 ` Michael Shulman
2010-09-24 15:30 Is equality evil? Mattias Wikström
2010-09-25 0:16 Is equality evil? Fred E.J. Linton
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