The Geometric McKay Correspondence (Part 2)

Last time I sketched how the Dynkin diagram arises from the icosahedron. This time I’m fill in some details. I won’t fill in all the details, because I don’t know how! Working them out is the goal of this series, and I’d like to enlist your help.

(In fact, I’m running this series of posts both here and at the n-Category Café. So far I’m getting more comments over there, so I suspect the serious helping will happen there. You may want to pop over there to see what people are talking about.)

R...