From: David Roberts <droberts@maths.adelaide.edu.au>
To: categories@mta.ca
Subject: Re: evil (fwd) Re: Quantum computation and categories
Date: Sun, 3 Jan 2010 20:31:48 +1030 [thread overview]
Message-ID: <E1NRRmo-0000OP-QQ@mailserv.mta.ca> (raw)
In-Reply-To: <E1NPykr-0001KX-SZ@mailserv.mta.ca>
> but in general, evil exists. every
> functor can be factored as an identity-on-the-objects-functor (ioof),
> followed by an embedding. the embedding is good, but ioofs are evil, and i
> think that they deserve their name. lord knows how much we use them.
An ioof is 'evil' in a subtly different way to what was discussed, in
my opinion, in that the property of being such a functor is not
invariant under natural isomorphism. This is then really a
2-categorical notion of evil. Are there many examples/other commonly
used properties of functors that are evil in this way?
Happy new year
David
[For admin and other information see: http://www.mta.ca/~cat-dist/ ]
prev parent reply other threads:[~2010-01-03 10:01 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-29 0:07 Dusko Pavlovic
2009-12-31 2:01 ` in defense of evil Peter Selinger
2010-01-02 22:22 ` Dusko Pavlovic
2010-01-03 10:01 ` David Roberts [this message]
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