Our institute is about to move to a new location. We all have to pack our books and papers into crates to be taken to the new building, where we will unpack them again (if they arrive intact, or at all). Of course that means going through old files deciding if they should be packed to move or just thrown out. Occasionally you come across something that can actually be dealt with (it’s probably late, but better late than thrown out, you might think).

Today the internal post brought me the last two homeworks from an Axiomatic Set Theory course I completed in 2004.

(Ah, nostalgia. “The idea for this construction is due to Alex Ma. The messy details and confused notation are entirely my own.”)