Hello list, I am preparing a series of seminars about sheaves on toposes of the from Set^D, where D is a finite poset, for a mixed audience containing non-logicians, non-categorists, non-topologists, non-algebraists, and even non-mathematicians (e.g. physicists), and to keep everything very elementary I am using lots of explicit examples, taking D to be posets like "Vee" and "Kite" (my heroes!), depicted below... {1,2,3} ^ ^ / \ 1 2 {1,3} {2,3} \ / ^ ^ v v \ / 3 {3} ^ | {} I am basically taking Harold Simmons's "The point-free approach to sheafification", J.L.Bell's "Toposes and Local Set Theories", Fourman and Scott's "Sheaves and Logic", and chapter A4 of the Elephant, and reworking some of the main theorems into that setting... Actually (and I only dare to confess this because I am far away enough, so no one will going to be able to beat me up with a big stick!8-) I am trying to find _finite_ examples that are expressive enough, and then see how much of the theory I can explain clearly by starting from these examples and then generalizing... Anyway: I am having to discover lots of the nice properties of toposes of the form Set^D by myself - the topologies involved are finite, so they're even "better" than Alexandroff topologies... - because I have never seen those categories being explicitly discussed in detail anywhere. So: anyone has any papers, theses, notes, slides, etc, to recommend? Thanks in advance, Eduardo Ochs eduardoochs@gmail.com http://angg.twu.net/ [For admin and other information see: http://www.mta.ca/~cat-dist/ ]