CMSC 250
Discrete Structures
Spring 2007
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May 20
End-of-course announcements:

  • Final course grades should be available shortly via Testudo.

  • A copy of all of your grades is being emailed to whatever email address you have on file with the University, so you can find out your final exam score, and verify that all of the grades we have recorded for you are correct. If you see any discrepancy in your grades, let me know right away when you get the mail (please call rather than sending email.)

    In this mail, excused absences for missed coursework are indicated by "avg".

  • The final exam results were:
    Average: 148.2 out of 200 (74.1%)
    Standard deviation: 29.3
    Distribution:
    180-200 (90-100%): 18
    160-179 (80-89%): 18
    140-159 (70-79%): 28
    120-149 (60-69%): 21
    100-119 (50-59%): 11
    80-100 (40-49%): 7

  • Everyone's lowest quiz, and lowest homework, were dropped, in calculating final grades. Using this information, and the weights in the course syllabus, you can calculate your final overall course score.

  • The average overall score for all students for all coursework was 75.1.

  • Anyone interested may see their final exam in my office, after final grades have been submitted, but according to the University policy I have to keep them. Call me after final grades have been submitted if you want to see your final (please call rather than sending email).

  • If you would like to contact me about anything after this time please call me in my office, rather than sending email. If I'm not in my office, please leave a message.

    Note that I am not teaching this summer and I will rarely be in my office during the next couple of weeks. Just leave a message and I will call back before the next time I plan to be on campus.

  • This class webpage may be taken down over the summer, so if there's anything you want to save from it which you haven't already copied, you should probably get it soon.

May 8
Solutions to the third exam are now posted.
May 7
The slides from lecture 42 (from class today) were updated after being posted, because I added a slide for something I just covered on the board during class. So if you already copied today's slides you may want to copy them again.
May 2
Solutions to Homework #11

Note: problem #4 is not worded correctly, but we didn't realize this until today, since no one had asked any questions about that problem during office hours. The answer to that problem in the solution assumes that all SUMs are possible which was the original intention of the problem, but this is not actually the case. We'll give full credit to any reasonable answer to this question. (The actual number of subsets of A of size 5 which have the same SUM is actually 94 as opposed to 112, and the actual number of subsets of A of size 3 which have the same SUM is actually 67 as opposed to 88, but you weren't expected to really calculate these.) Sorry for any confusion in regards to this problem, but no questions were asked about it until just before discussion section today, so we weren't aware of the issue.
April 23
If you lost your textbook for the course, please see me after lecture, and describe the book and where you might have lost it.

Suggestion to everyone- take a moment every semester to write your name and phone number in your textbooks and notebooks. I often find lost textbooks (which are expensive to replace, and have resale value) and notebooks (which have irreplacable notes and work), and almost never is there a name written in them, so there's often no way to return them to the owner despite trying to do so.
April 8
Some typographical errors were corrected in the answer to the last problem in the Homework #8 solutions; some <= symbols were written as = or as >. The inductive step was also changed slightly, to make it more similar to similar problems done in class. Sorry for any confusion.
April 6
Two typographical errors were corrected in the Homework #8 solutions. In the inductive hypotheses for problems 4 and 5, ap should have been ai.
April 4
March 26

  • Be sure to use the changed version given in class of question #3 on Homework #7.

  • Here are the extra propositional and predicate logic practice proof problems discussed in class:

    Questions

    Solutions

February 25
In Section 6 of the syllabus, please delete the sentence about resolving questions about project grading. It was supposed to refer to resolving questions about homework grading. It should be replaced with the sentence "If you feel a mistake was made in grading any homework question, please attach a sheet of paper to the homework and write no more than three sentences specifically describing what you feel the grading problem is, and give it to your TA within a week."
February 9
The two clarifications and one correction to Homework #3 referred to in class today:

  • For #2, be sure you recall exactly which numbers are prime in order to construct the circuit correctly. The definition of a prime number was given in lecture today, and is in Section 2.1 of the text.

  • For #3 (c), to make grading easier, you should draw a separate, independent circuit for each of the output bits, rather than a combined circiut. So your answer should have two circuits, both with inputs p, q, and r.

  • #5 (g) should be changed, and, instead of the original wording, should instead read:

    There is only one student who attended no classes.

February 2
Some students were in discussion section this week but didn't get the homework. If you're one of them, get in touch with me (send me email) and I can send you a copy.
January 24
Welcome to CMSC 250! The lecture slides from today have now been posted.