CS170: EFFICIENT ALGORITHMS & INTRACTABLE PROBLEMS

INSTRUCTOR: Alistair Sinclair (sinclair@cs)
LECTURES: Tuesday, Thursday 09:30-11:00
PLACE: 306 Soda
OFFICE HOURS: Monday 1:30-2:30, Tuesday 11:30-12:30 in 677 Soda

 TEACHING ASSISTANTS:
Yan Huang (yan@icsi.berkeley.edu, 464 Soda, 666-2942)
Omar Khan (omar@eecs, 592 Soda, 642-5422)
Junming Yin (junming@eecs, 594 Soda, 642-1017)

 DISCUSSION SECTIONS:
101: Tu 3-4, 3 Evans; Omar
102: Tu 4-5, 289 Cory; Junming
103: W 10-11, 75 Evans; Yan
104: W 11-12, 75 Evans; Omar
105: W 1-2, 3 Evans; Junming

 TA OFFICE HOURS:
Yan: W 9-10, Soda Alcove 511
Omar: W 3-4, Th 11:30-12:30, both in Soda Alcove 511
Junming: M 4-5 in Soda Alcove 711, W 2-3 in Soda Alcove 751

RECENT ANNOUNCEMENTS


LECTURES

The following is a list of topics covered, together with the corresponding lecture notes and suggested reading from the CLRS textbook.

Topic Readings
1 Overview Notes [ps] [pdf]
CLRS Chapters 1, 2, 3
2 Divide-and-Conquer; Recurrences Notes [ps] [pdf]
CLRS Chapter 4, Appendix A, Sect 33.4
3 Decompositions of Graphs Notes [ps] [pdf]
CLRS Chapter 22 (omit 22.2)
4 Paths in Graphs Notes [ps] [pdf]
CLRS 22.2 & Chapter 24 (omit 24.1, 24.4)
5 Minimum Spanning Trees; Greedy Algorithms Notes [ps] [pdf]
CLRS Chap. 23, 21 (omit 21.4), 16.3
6 Lempel-Ziv algorithm, lower bounds and entropy Notes [ps] [pdf]
7 Dynamic Programming Notes [ps] [pdf]
CLRS Chap. 15
8 Linear Programming Notes [ps] [pdf]
CLRS Chap. 29
9 NP-Complete Problems Notes [ps] [pdf]
CLRS Chap. 34
10 Coping with NP-Completeness Notes [ps] [pdf]
11 The Fast Fourier Transform Notes [ps] [pdf]
CLRS Chap. 30

HOMEWORKS

All homeworks are due Thursday at 3:30pm unless otherwise stated. Turn in your homeworks in the box labeled "CS170" on the 2nd floor of Soda Hall. Please begin your answer to each problem on a new sheet of paper. Please ensure that each sheet is labeled with your name, SID number, section number, and "CS170--Spring 2006". You risk receiving no credit for any homework submitted without this information. Please take the time to write clear and concise solutions; we will not grade messy or unreadable submissions. The lowest two homework scores will be dropped. No late homeworks will be accepted.

EXAMS

There will be two midterms and one final. Dates and other details will be announced in due course.

QUIZZES

There will be a short quiz at the beginning of class on randomly selected dates. The quiz will consist of a small number of very simple questions related to the material of the previous class. The two lowest quiz scores will be dropped. The motivation for the quizzes is twofold: (1) to encourage you to review the material of each class before the next class; (2) to encourage on-time arrival at lectures.

ASSESSMENT

Your grade in the class will be determined as follows: Homeworks 20%; Midterms 20% each; Final 35%; Quizzes 5%.

COURSE POLICIES

Prerequisites: Formal prerequisites are CS61B and either CS70 or Math55. In particular, you should be comfortable with mathematical induction, big-O notation, sorting algorithms, basic data structures and binary heaps. If you need to refresh any of this background, you should refer to the relevant portions of the CLRS book (see below). It is also assumed that you have experience with programming in a standard imperative language such as C, C++ or Java. Although most homeworks will be pencil-and-paper exercises, you may also be expected to do some small programming assignments.

Readings: Lecture notes will be posted on this web page on or before the day of the relevant class; most of these notes are draft chapters of a book in preparation by Sanjoy Dasgupta, Christos Papadimitriou and Umesh Vazirani. For additional background and examples, it is recommended that students consult the book Introduction to Algorithms, by Cormen, Leiserson, Rivest and Stein, Second Edition, MIT Press, 2001 (which we shall refer to as CLRS). Pointers to the relevant sections of this book will also be provided as we go along.

Contact Information: The instructor and TAs will post announcements, clarifications, hints, etc. to this website and/or to the class newsgroup, ucb.class.cs170. Hence you must check this website and the newsgroup frequently throughout the semester. For information on how to access UCB newsgroups, go here (see also here for more).

If you have a question, your best option is to post a message to the newsgroup. The staff (instructor and TAs) will check the newsgroup regularly, and if you use the newsgroup, other students will be able to help you too. When using the newsgroup, please avoid off-topic discussions, and please do not post answers to homework questions before the homework is due.

If your question is personal or not of interest to other students, you may send email to cs170@cory.eecs. Email to this address is forwarded to the instructor and all TAs. We prefer that you use this address, rather than directly emailing the instructor and/or your TA. If you wish to talk with one of us individually, you are welcome to come to our office hours. If the office hours are not convenient, you may make an appointment with any of us by email. Please reserve email for the questions you can't get answered in office hours, in discussion sections, or through the newsgroup.

In a class this large, it can be challenging for the instructor to gauge how smoothly the class is going. We always welcome any feedback on what we could be doing better. If you would like to send anonymous comments or criticisms, please feel free to use an anonymous remailer like this one to avoid revealing your identity.

Collaboration: You are encouraged to work on homework problems in study groups of two to four people; however, you must write up the solutions on your own, and you must never read or copy the solutions of other students. Similarly, you may use books or online resources to help solve homework problems, but you must credit all such sources in your writeup and you must never copy material verbatim. Warning: Your attention is drawn to the Department's Policy on Academic Dishonesty. In particular, you should be aware that copying solutions, in whole or in part, from other students in the class or any other source without acknowledgment constitutes cheating. Any student found to be cheating risks automatically failing the class and being referred to the Office of Student Conduct.

Regrading Policies: Regrading of homeworks or exams will only be undertaken in cases where you believe there has been a genuine error or misunderstanding. Bear in mind that our primary aim in grading is consistency, so that all students are treated the same; for this reason, we will not adjust the score of one student on an issue of partial credit unless the score allocated clearly deviates from the grading policy we adopted for that problem. If you wish to request a regrading of a homework or exam, you must return it to your section TA with a written note on a separate piece of paper explaining the problem. The entire assignment may be regraded, so be sure to check the solutions to confirm that your overall score will go up after regrading. All such requests must be received within one week from the date on which the homework or exam was made available for return.

SOME HELPFUL HINTS

The following tips are offered based on our experience with Upper Division classes in CS Theory. If you follow these guidelines, you will make life much easier for yourself in this class.

1. Don't fall behind! In a conceptual class such as this, it is particularly important to maintain a steady effort throughout the semester, rather than hope to cram just before homework deadlines or exams. This is because it takes time and practice for the ideas to sink in. Make sure you allocate a sufficient number of hours every week to the class, including enough time for reading and understanding the material as well as for doing assignments. (As a rough guide, you should expect to do at least one hour of reading and two hours of problem solving for each hour of lecture.) Even though this class does not have any major projects, you should plan to spend as much time on it as on any of your other Upper Division technical classes.

2. Take the homeworks seriously! The homeworks are explicitly designed to help you to learn the material as you go along. Although the numerical weight of the homeworks is not huge, there is usually a strong correlation between homework scores and final grades in the class. Also, regardless of how well you did on the homework, read the sample solutions, even for the problems you got right. You may well learn a different way of looking at the problem, and you may also benefit from emulating the style of the solutions. (In science people learn a lot from emulating the approach of more experienced scientists.)

3. Make use of office hours! The instructor and TAs hold office hours expressly to help you. It is often surprising how many students do not take advantage of this service. You are free to attend as many office hours as you wish (you are not constrained just to use the office hours of your section TA). You will also likely get more out of an office hour if you have spent a little time in advance thinking about the questions you have, and formulating them precisely. (In fact, this process can often lead you to a solution yourself!)

4. Take part in discussion sections! Discussion sections are not auxiliary lectures. They are an opportunity for interactive learning, through guided group problem solving and other activities. The success of a discussion section depends largely on the willingness of students to participate actively in it. As with office hours, the better prepared you are for the discussion, the more you are likely to get out of it.

5. Form study groups! As stated above, you are encouraged to form small groups (two to four people) to work together on homeworks and on understanding the class material on a regular basis. In addition to being fun, this can save you a lot of time by generating ideas quickly and preventing you from getting hung up on some point or other. Of course, it is your responsibility to ensure that you contribute actively to the group; passive listening will likely not help you much. And recall the caveat above that you must write up your solutions on your own.