pg 11 has information on the Y combinator. Wikipedia has a better explanation of the proof. https://en.wikipedia.org/wiki/Fixed-point_combinator#Fixed_point_combinators_in_lambda_calculus
Now I understand the proof, but I’m still confused on how it “simulates” recursion.
This post https://riceissa.wordpress.com/2014/03/18/two-definitions-for-the-least-upper-bound/ has been ported into Markdown and is hosted on my GitHub website here https://riceissa.github.io/math/lub.html . (Mostly to test how Mathjax+Jekyll+Github work.)
I’ve begun collecting resources for the UW. There’s a page on this blog for posting comments, but the most current version is available here.
Scratch space 