CS20a Announcements

21 October 2002

10:00 am - IMPORTANT announcement from Jason

First, my apologies for two things. First, the level of difficulty for the labs was much more than expected. Second, I had wished to post this message earlier, but I was offline over the weekend.

-----> If you don't read anything else, read #3 below <-----

From talking with the TAs, it seems that the main problem with lab2 is the OCaml part. Most of you seem to know what the algorithms are, and what is required to solve the problem, but then there is all this stuff with modules, Sets, functors, etc. Also, it would have helped if I had posted a more extensive guide of what you needed to do, than simply saying "build a dfa from a nfa, etc."

The purpose of this course is to teach you the fundamental concepts and theory of CS. The labs are supposed to ground these concepts by seeing how they are applied. I don't want them to dominate your work by any means. We'll still have labs, and we'll still use OCaml, but I'll try to match them better with your abilities (and I'll try to give more informative writeups).

Here are some important announcements:

1. HW3 will be posted by noon today. It will be short, due Thursday in class.

2. Lab3 is: finish lab2 and make it as elegant as possible.

3. I will be going over the solution for lab2 in class on Tuesday. Bring a pencil and paper; these lecture notes will not be posted.

4. As Nathan mentioned, lab2 will be graded as extra-credit using max (0, score - 50).

Last, and certainly the most contraversial. I know that class is too early, it is too early for me too. Attendence in lecture is low.

The problem is that I don't know most of you, and I don't know what kinds of problems you may be having. So:

4. There will be a pop-quiz in each class with probability 0.5. Quizzes will cover material from class and the labs. Quizzes are worth 20 points, (for comparison, HW are worth 100 points). I will grade the quizzes myself, and hand them back in the next class. If you missed a quiz because you missed class, you can take it during my office hours or by appointment.

13 October 2002

3:00 pm - Correction to Homework 2

The figure for Exercise 1 on Homework 2 was drawn incorrectly. There were two errors:

• No explicit start state.
• The arrows between the two states on the right of the original diagram were drawn backwards, thus making the machine non-deterministic.

Both of these errors have been corrected. Corrected versions of the homework have been posted. With the corrected diagram, it is the case that the machine prints out ``nnyny'' given the string ``01100''.

8 October 2002

11:28 am - The mailing list archives are alive

You can read them here or follow the link on the mailing lists page.

8 October 2002

8:45 am - Clarification of grading for Homework 1

Homework 1 counts as one assignment, not two. The entry for a ``lab1'' has been deleted from Osaka. You should turn in your modified dfa.ml and other files using cs20-submit hw1.

7 October 2002

10 am - Recitation tonight and updated TA office hours

This is just a friendly reminder that Brian will be giving a recitation tonight from 7:30 - 9:00 pm in Jorgensen 74. He will go over more things in OCaml and the lab portion of the hw1.

Also, all the TA's have posted their office hours.

Important: For this week only, Jason Frantz will have his office hours from 4-6 pm this Tuesday (tomorrow), instead of what's posted on the web page.

3 October 2002

11 pm - Next recitation

The next recitation for CS20 will be held on Monday, from 7:30 pm to 9:00 pm in 74 Jorgensen. After a very brief review of some of the things Nathan presented tonight, Brian will go on to cover several more types and expression forms in the OCaml programming the language. By the end of the recitation, we should have covered all the OCaml that you will need to do Lab 1.

Feel free to come with any questions you may have about OCaml.

5 pm - Final time/location for first OCaml recitation

The first recitation will be tonight from 8:30 to 10 PM in Jorgensen 74. There will be a second recitation early next week but it will not cover the same material! This recitation is an intro to OCaml and will cover roughly the first four chapters of Dr. Hickey's book. The next recitation will cover later chapters in the book.

10:30 am - Corrections to lecture:

• Slide 6: {a} = {epsilon, a, aa, aaa, ...} should be {a}* = {epsilon, a, aa, aaa, ...}.
• Slide 10: In the figure, q4 should be q3.
• Slide 12: Under the second bullet point, delta(q, epsilon) = q should be delta-hat(q, epsilon) = q.
• Slide 16: The transition function for the machine that recognizes the intersection should be defined as follows: delta( (q1,q2), c ) = ( delta1(q1,c), delta2(q2,c) ).

Hopefully, we'll be able to post a corrected version of the slides later today.

2 October 2002

9:15 pm - CS Account Setup: We will be emailing grade reports to your CS account. If you prefer that mail be sent to another email account, you'll need to run the following:

echo username@foobar.com > ~/.forward ; chmod 644 ~/.forward

This will automatically forward all email sent to your CS account to username@foobar.com. (Obviously, you'll need to change that email address to some real account). Other than that, the CS20 Osaka programs and the OCaml compiler should be readily accessible through the default path.

7:15 pm - First OCaml Recitation: We will be holding a recitation on OCaml tomorrow, Thursday, Oct 3, from either 7:30-9 or 8:30-10 PM in Jorgensen 74. If you care about what time the recitation happens, show up to class and place your vote.

This recitation will cover basic OCaml syntax, types, and expressions, and do a brief overview of functional programming. We'll essentially be covering the first four chapters of Dr. Hickey's OCaml book. If you don't know at least one functional programming language then you're strongly advised to attend!

3:45 pm - Lab0 and CS Accounts: We (as TAs) have no control over when CS accounts will be given out to students in CS20; you need to contact the CS sysadmins for inquiries concerning accounts. Their homepage is here.

We are aware that many of you still do not have accounts, and that without an account, you cannot submit (or even possibly do) lab 0. Do not worry about this. Lab 0 will count little toward your final grade, and as long as it is turned in by sometime next week, we will not consider it late. Just turn it in as soon as you can so that we can verify that the submission system is working.

1 October 2002

10:00 am - Correction to lecture: On slide 24, there is a slight error in the argument. In order for the diagonalization argument to be completely correct, you need to drop the zero before the decimal point on each of the numbers in the listing. Otherwise, it's possible that the number constructed will match the first number in the listing since they will both start with zero.

30 September 2002

2:00 pm - Accounts and mailing lists: All students in CS20 need to email cs20-admin@metaprl.org with their CS account user name. If you do not have an account on the CS cluster, you need to request one. UGCS and ITS accounts will not work. Additionally, you should send email to cs20-class-subscribe@metaprl.org so that you can be on the class email list.