The three books I have authored or co-authored all contain a chapter of about 40 pages that is an introduction to category theory. They are largely identical (the one for Acyclic Models has a an added section on categories of fractions, needed for that book). The one in TTT is already freely available and, with Charles's permission, I would happily post that in whatever place you would like. Michael On Wed, 17 Sep 2008, R Brown wrote:
There are already some pretty good categorical entries on wiki; I have modified some of the entries on groups, actions, equivalence relations, to include references to groupoids, which has resulted in hits. But we should also consider planetmath.org (entries are contributed under the terms of the GNU Free Documentation License (FDL)) which allows for group work and is not so open as wiki to general modification. It needs a group of you wonderful energetic people to engage with reviewing what is on wiki and planetmath and making sure they express what is fealt to be desirable!
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