# Lecture Notes 2016/09/09

Today we continue the first stable marriage handout, although we’re skipping some pieces that you have a good sense of from the reading.

I report on the pre-class quiz below. Short version: 85% of those who took the quiz earned 2/2; only 2% earned 0/2. Thanks for doing the readings!

Next time, we continue stable marriage but introduce reductions, which we’ll use frequently to relate one problem to another. (We’ll use reductions to solve new problems in terms of old ones. Intriguingly, we’ll also eventually use reductions in the opposite way: to establish that we don’t know how to (or cannot) efficiently solve new problems by relating them to—reducing to them from—old ones.)

Important notes for today:

• Come to tutorial next week prepared for your tutorial quiz. The collected quizzes, plus possibly an extra problem, will become your assignment. (We’ll post each tutorial’s quiz question as the tutorial ends so everyone can start the assignment at the same time.)
• Follow along with the worked example in the screencast (and a blank copy of the problem). I was behind on this; so, the pre-class quiz is worth full credit if you answer it at all. (Suggestion: print the blank problem and try it, but after each major section or if you’re stuck even briefly, let the screencast help! This is not the way to study for an exam, but it will prepare you for class.)
• The next pre-class quiz is due by noon on 2016/09/12 and will be e-mailed to your ugrad.cs.ubc.ca account by 5PM today. It is about the worked example. Because I was behind on posting the worked example, you get full credit on the pre-class quiz if you submit it at all. So, submit it! (Our normal pre-class quiz pace will be ~1-2 per week, but the start of term is so exciting!!)
• Also read the syllabus on the course website. Early next week we’ll have a light-weight pre-class quiz about it.
• A sample solution to the first set of notes is available.
• If you wish to read ahead, I expect us to read at least these sections in this order (changes may happen but probably not drastic ones):
• The rest of Chapter 1 (and, for every chapter we read, the chapter intro)
• Chapter 2 (largely review), with emphasis on 2.3
• Chapter 3
• Sections 4.1-4.7 of Chapter 4 (a bit of which is likely review)
• Sections 5.1-5.4 of Chapter 5, plus the Master Theorem on Wikipedia
• Sections 6.1-6.6 and 6.8 (which is likely review) of Chapter 6
• Sections 8.1-8.5, maybe 8.6, 8.7, 8.8, and 8.10 of Chapter 8. Note that 8.10 is useful to read early and reread as you work through this chapter.

P.S. Our first pre-class quiz went well! 151 people responded (out of 187 registered and on the waitlist). Of those, 128 earned 2/2, 20 earned 1/2, and 3 earned 0/2. (The marking scheme partly responsed to how hard the questions proved to be. The scheme was more complicated than this, but I believe in the end this is also coincidentally correct: correct response to the two easiest questions (about increasing and decreasing preference orders for men and women) plus any one other earned a 2/2, correct responses to either of the easiest questions earned a 1/2. Incorrect responses to both earned a 0/2.

P.P.S. If you don’t receive next class’s pre-class quiz by the end of today, please e-mail cs320@ugrad.cs.ubc.ca with your name, student #, ugrad.cs.ubc.ca login ID, and whether you are on the waitlist or in the course.