To prepare for Wednesday's lecture

Last year's note on convexity & friends is long, and I don't expect you to browse more than a bit of the beginning. Given the short time, I suggest you first browse through the following subset of the first few pages:

. page 1: read the first half page; notice the examples, but need not attempt to show anything

. page 2: read the claim, but not the proof; read the note the last two lines

. page 3

. page 4 (nearly empty - but carries a lot of substance)

. For page 5: draw your "Math 2" concave function of one variable. "Fill the graph with water" and notice that the water is a convex set. Notice that a concave function is a convex turned on its head. Try to visualize both of these properties for a function of two variables.

Here is the note: https://www.uio.no/studier/emner/sv/oekonomi/ECON4140/v18/lectures-ls/m3_2018lect7ffls.pdf