I thought about the proof of the first and second graph principles (a terminology from the Boolos/Burgess/Jeffrey book, which isn’t standard as far as I know; the two principles state that a total or partial function is recursive if and only if its graph relation is semirecursive).

I spent more time reading about the Kleene fixed point/recursion theorem.

I went back to Tao’s Analysis I to think about proposition 6.4.12 (a), (b), and (c).

(This was day 2 of a caffeine reset, which made thinking difficult.)