Lecture 4

We covered examples of rephrasing a claim (e.g. proof by contrapositive) and proof by cases (see sections 3.6-3.13).

We also looked at the Euclidean Algorithm, as an excuse to talk about divisibility concepts from the early part of chapter 4. We ended partway through a proof that output value isn't changed when we reset the variable values in the middle of the loop.

Announcements

• Brianna Ifft gave a promo for the WCS (Women in CS) society, which would love to have you as a member (even if you are male). Watch for announcements of events and "general meetings" in the Siebel lobby (which tend to have good food).
• Reminder: discussions start today
• First examlet coming up next Tuesday, start of class. Expect to collect two separate sheets as you come in. This time, we won't randomlize seating but please don't sit next to your friends. About 25 minutes long, followed by a brief break and a short lecture.
• Notice that there is still a reading quiz for next Tuesday.