It starts poetically, with a story involving parallel universes, and ends prosaically, with a link to a paper to appear in LPAR 2013.
This post presents a simple lemma related to the Knaster-Tarski fixed-point theorem. I used to think it's obvious, but today I set out to write down the full proof and I was somewhat surprised that I got stuck for awhile. As often is the case, I got unstuck with some help from Rasmus, and his slides in this case.
Psychologists developed a cute framework for structuring our thougths about our thoughts. Basically, you imagine two dwarves sitting inside your head, one chatty and stupid, the other lazy and slow. Here I explain how rules-of-thumb help the stupid one take over some jobs from the lazy one.