Slides from class: class21.pdf
Problem Set 9 is due on Monday, 17 April. The latex template is https://www.overleaf.com/read/mqwmbzjppfbv.
If the key opening door reduction isn’t exciting enough for you (or you’re just a fan of 1980s TV shows), you may want to watch this video: Proof by Reduction (from Fall 2020 course).