3 Jan
2010
3 Jan
'10
10:01 a.m.
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/ ]