ECS20 - W22 - Lecture 5 (3T): Proofs

Online lecture from 1/19/2022.  Sundry proofs, chosen to illustrate recurring ideas and themes. I had prepared 11 examples, and we got through 8 of them. Also included some general comments on finding and exhibiting proofs.  Hopefully this lecture pairs well with the Lockhart reading, which I have assigned.