Announcements

Welcome to Fall 2007 91.503 Algorithms announcements page. Visit this page regularly to find out about homework assignments, exams, and other topics of interest.

• Wednesday, December 26, 2007:
  1. Final Exam grades; and
  2. all grades
• Saturday, December 15, 2007:
  1. HW7 solutions.
• Friday, December 14, 2007:
  1. Here are some partial notes for the solutions to Exam 2.These are not complete solutions, but if you know the material, this will be sufficient for you.
  2. Solutions to HW7 will be posted tomorrow (Saturday, December 15).
• Wednesday, December 12, 2007:
  1. Solutions to HW6 (PDF, 587 kb);
  2. grades so far (11 December 2007), 60% for exams (30% and 30%), 40% for HW1-6 (HW1-5 = 40%/7; HW6 = 2 * 40%/7).
• Wednesday, December 5, 2007:
  1. Exam 2 grades; and
  2. grades so far (5 December 2007), 60% for exams (30% and 30%), 40% for HW1-5 (8% each).
  3. Basic cryptography class presentation(PDF, 714 kb)
  4. RSA math class presentation(PDF, 225 kb)
• Tuesday, December 4, 2007:
  1. Homework assignment 7 -- Flow networks (Ch. 26) + Linear programming (Ch. 29) due Tuesday, December 11, 2007, 11:59 pm.
  2. [Optional -- extra credit + extra learning] Homework assignment 8 -- RSA encryption (Ch. 31) + NP-Completeness (Ch. 34) due Sunday, December 16, 2007, 11:59 pm.
• Monday, November 26, 2007:
  1. HW grades clarification: some of you have asked about "extra credits" and grades over 100. For HW5 you had the option to submit more than the prescribed 100; for HW6 (which will count as two assignments), more than 200. HW5 grades published so far include grades over 100. However, I do not intend to calculate those as more than 100 (200 for HW6). What I will do, though, is use "extra credit" submissions in borderline cases to move up a grade. In general, of course, the more you do the better you are off (mostly for the learning). And if you do them, you might as well submit them.
  2. Exam advise: I have heard "through the grapevine" that some of you are hard at work trying to gather as many solutions to the book problems as you can to bring with you to the exam tomorrow. If you are trying to do so by solving as many problems on your own, ode to you; this is probably the best way to learn and do well in the exam. If, on the other hand, you are trying to collect as many solutions as possible from elsewhere (as, rumors are telling me some of you are trying to do) you should stop wasting your time: there will be no question from the book. And even if there were, I would know if you copy an answer, and this time, your grade would be zero. No arguments. So put your efforts where they'll pay off.
• Tuesday, November 20, 2007:
  1. Grades through HW5, as of November 20, 2007.
  2. Solutions to HW5 (PDF, 732 kb).
• Tuesday, November 13, 2007:
  1. Homework assignment 6 -- Single-Source Shortest Paths (Ch. 24) and All-Pairs Shortest Paths (Ch. 25) has been posted. It is due Tuesday, November 27, 2007, 11:59 pm. This is the day of our second exam, so you might want to have these complete (and, thus, submitted) before class.
  2. Because of error in the previous posting, I have reposted grades, as of November 12, 2007 (may not include grade changes resulting from your last class requests for regrading; any warranted changes will be posted later). I now recalculated raw grades; assignments 1-4 were given a total of 50% and exam 1 was given the other 50%. As we add assignments and exams, I will recalculate current grades. As stated previously, the relative grades will depend on other people's results, as well as your own.
  3. Solutions to HW4 (PDF, 195 kb) have been posted. (The title -- HW3 -- is wrong; the solutions are for HW4.)
  4. Presentations:
     1. All-Pairs Shortest Paths: Full color (PDF, 234 kb) and printer-friendly (PDF, 232 kb).
     2. Maximum Flow: Full color (PDF, 626 kb) and printer-friendly (PDF, 623 kb).
• Wednesday, November 7, 2007:
  1. Grades, as of today (November 7, 2007) have been posted. I have included a raw total, which has been calculated based on the four assignments that have been graded, and the first exam. I have also added a relative total, which is just a normalization to the highest raw grade. These should give you your current standing, and with a little "what/if" calculations you can get an idea of your projected grade at the end of the semester, assuming certain grades for the remaining assignments and exams. Clearly, the relative numbers depend on other people's results.
  2. Final exam: One of you has pointed out that the final exam schedule for graduate courses is the same night as the class meet, but during exam week, and starting at 6:00 pm. Therefore, our final exam will take place Tuesday, December 18, at 6:00 pm, in OS 311.
• Tuesday, November 6, 2007: As mentioned in class, the final exam has been scheduled by the registrar to Tuesday, December 18 at 8:00 am. Recognizing that many of you have day jobs, which would make this time a difficulty, I have proposed to reschedule to the evening. One option is to just move it to the same day (Tuesday, Dec. 18) at 5:30 pm -- our regular day/time. That evening, I will not be able to be here, but the TA has confirmed she could. We could also try for an earlier evening, essentially, Monday, December 17, same time. Either case, I'd have to verify that I can have a room. Please let me know as soon as possible ONLY of any problem you might have with either night. If either night is OK for you, please do not respond.
• Tuesday, October 30, 2007:

  1. Exam1 grades have been posted.

     Here is a summary of my comments last class:

     1. Most of you seemed to have a hard time with the recurrence question (#5); this is 404 (undergraduate algorithms) material you should have at the tips of your fingers. Please review/revise.
     2. The only acceptable way to present an algorithm is code. A similar style to the one presented in class and in the text is recommended, but other styles are acceptable. Long-hand ("story") text is not acceptable. Next time I'll penalize!
     3. Repeating the details of the question as a long-winded story will not mask your not knowing the answer; neither will padding your answer with additional long stories. Next time I'll penalize!
     4. If you are copying an answer from a source, make sure (at least) that you understand what you are copying. And please give the reference where you copied the answer from. It's funny to get an answer that, e.g., announces that the approach will be "greedy" but proceeds to describe a dynamic programming solution exactly as it can be found somewhere (I know many if not all those solutions available for download).
• Tuesday, October 30, 2007:
  1. Exam1 partial grades (questions 1, 2, 4, 5, 6, and 7) have been posted. The rest (3, 8) are coming up soon.
  2. Full color preliminary version (PDF, 6.77 mb) and a printer-friendly version (PDF, 6.4 mb) of the coming class presentation, Shortest Paths.
• Thursday, October 25, 2007:
  1. Homework assignment 5 -- Graph Algorithms has been posted. It is due Tuesday, November 6, 2007, 11:59 pm.
• Monday, October 15, 2007:
1. HW1-3 grades have been posted. For questions, please contact the TA, Minseo Park (mpark@cs.uml.edu, cc: me). Please note that some of you have not followed the requirements for academic honesty. You should have received a message from the TA. This first round, you are being treated with some compassion, any further violations will not be met with such compassion. Please do not test me on that!
2. Solutions to HW3 (PDF, 302 kb) have been posted.
• Thursday, October 11, 2007:
  1. I have sent to each one of you (to your cs.uml.edu address) a message with a number. This number will appear in grade distributions as your unique identifier. It is different from any other number you have, and only you, the TA, and I know this number, so this will preserve your privacy. Please contact me with your CS address if you haven't received such a message.
  2. Solutions to HW2 (PDF, 259 kb) have been posted.
  3. Homework assignment 4 -- Amortized Analysis has been posted. It is due Sunday, October 21, 2007, 11:59 pm, but I strongly recommend that you do as much of it as you can before our exam this coming Tuesday.
  4. Here are aggregate results for the first two assignments. Overall, results are pretty good; I'll get individual results out to you soon.

     	HW1	HW2
     MIN	0	0
     MAX	100	100
     AVG	85.46	73.32
     STDEV	30.08	25.66
     MED	96	80.75

• Tuesday, October 9, 2007: These presentations for the coming classes have been uploaded:
  1. Graphs, full color preliminary version (PDF, 6,486 kb),
  2. Graphs, printer-friendly version (PDF, 6,401 kb),
  3. MSTs (Minimum Spanning Trees), full color preliminary version (PDF, 3,341 kb), and
  4. MSTs (Minimum Spanning Trees), printer-friendly version (PDF, 3,292 kb).
• Tuesday, October 2, 2007:
  1. Homework assignment 3 -- Greedy Algorithms has been posted. It is due Tuesday, October 9, 2007, 11:59 pm.
  2. a full color preliminary version (PDF, 332 kb) and a printer-friendly version (PDF, 319 kb) of the coming class presentation, Amortized Analysis.
  3. the final version (PDF, 958 kb) and a printer-friendly version (PDF, 787 kb) of the Greedy Algorithms presentation.
  These are full slides, one per page. Hopefully, the quality will no longer be an issue.
• Friday, September 21, 2007:
  1. Homework assignment 2 -- Dynamic Programming has been posted. It is due Sunday, September 30, 2007, 11:59 pm.
  2. The following Class presentations have been uploaded:
     1. Dynamic programming algorithms (PDF, 306 kb)
     2. Greedy algorithms -- PRELIMINARY (PDF, 359 kb)
• Tuesday, September 11, 2007: Homework assignment 1 -- 91.404 review has been posted. It is due Tuesday, September 18, 2007, 11:59 pm.

Make sure to READ AND FOLLOW the Academic Honesty guidelines!

Important dates