CMSC203 Discrete Structures, Sections 0201, Spring 2008

News Archive

• [Tue May 27 12:55 2008]
  Final exam scores and letter grade have been posted on Blackboard.

  FYI, the average on the final was 75.6 (out of 100) and the average total score was 79.06.

• [Thu May 15 22:35 2008]
  Quiz 5 scores are available on Blackboard. Solutions to the quiz problems are available (for a limited time): Q5sol.pdf.

• [Tue May 06 21:23 2008]
  Here's the diagram for the sample space for the Monty Hall Problem I showed in class this afternoon: [MontyHall.gif]

• [Tue May 06 12:05 2008]
  Homework 13 posted.

• [Mon Apr 28 14:15 2008]
  Homework 12 posted. This is due Tuesday, May 6th. If you are looking for the homework due on Tuesday, April 29th, do Homework 11.

• [Mon Apr 28 13:47 2008]
  For Homework 11, you MUST show your work. Answers that consist of a single number will not receive very much credit.

• [Thu Apr 24 18:02 2008]
  Quiz 4 has been moved to Thursday, May 1st. No other dates have been changed.

• [Tue Apr 22 11:15 2008]
  Homework 11 posted.

• [Tue Apr 15 08:00 2008]
  Homework 10 posted.

• [Sat Apr 12 19:22 2008]
  The code for Homework 9 was modified. All occurrences of unsigned was removed because we really do want i to be -1. Funny, my compiler did not complain.

• [Tue Apr 08 08:00 2008]
  Homework 9 posted.

• [Fri Mar 28 20:10 2008]
  Grades have been posted to the course Blackboard site. You should be able to see your scores when you log into myUMBC and hop over to Blackboard. (We will only use Blackboard for grades.)

  Please look over your scores. If there are any discrepancies, please inform the instructor ASAP.

  So far, there have been 5 graded homework assignments (= 10 points), two quizzes (= 12 points) and 6 in-class worksheets (about 2 points). The points for in-class work is approximate because it depends on the total number we have by the end of the semester. Thus, about 24 percent of your final grade has been determined.

  FYI, the class average is 20.58 which is about 85.6 percent of 24. The class is doing quite well as a whole.

• [Thu Mar 27 10:40 2008]
  Reminder: There is a midterm exam on Tuesday, April 1. This has been on the syllabus since the beginning of the semester.

• [Thu Mar 27 10:40 2008]
  Homework 8 posted.

• [Wed Mar 12 23:40 2008]
  Homework 7 posted.

• [Tue Mar 11 23:45 2008]
  Our TA Don Dimitroff will not have office hours on Monday, March 24th (Monday after Spring Break). He'll have extended office hours on Tuesday instead.
  • Canceled: Office Hour on Monday, March 24th.
  • Extended: Office Hours on Tuesday, March 25th, 2:30 to 4:30.

• [Thu Mar 06 17:11 2008]
  Homework 6 posted.

• [Sat Mar 01 17:25 2008]
  Posted lecture notes on the Chinese Remainder Theorem.

• [Thu Feb 28 17:10 2008]
  Homework 5 posted.

• [Thu Feb 28 17:10 2008]
  There are tons of hits when you Google "Chinese Remainder Theorem". Here's one that is compatible with the presentation today: [ link ].

• [Thu Feb 21 09:25 2008]
  Homework 4 posted.

• [Fri Feb 15 21:45 2008]
  The lecture notes on Methods of Mathematical Proof is now complete. You will find most of the proof examples from the last 3 lectures written up there. From this point forward, we will be following the textbook more closely.

• [Fri Feb 15 16:22 2008]
  Tip from Isaac Jensen: If you are not having enough fun with planar graphs, here's a web game you can try: [link].

• [Thu Feb 14 08:10 2008]
  Homework 3 posted.

• [Wed Feb 13 12:45 2008]
  The notes on proof methods have been expanded and broken up into smaller web pages.

• [Wed Feb 13 12:45 2008]
  FYI, our TA Don Dimitroff will not have office hours on Monday, February 18th (President's Day). He'll have extended office hours on Tuesday instead.
  • Canceled: Office Hour on Monday, February 18th, 2008.
  • Extended: Office Hours on Tuesday, February19th, 2008 2:30 to 4:30.
  • Normal Office Hours: Mon-Tue-Wed-Thu 2:30-3:30.

• [Mon Feb 11 12:05 2008]
  Lecture 4 (2/7/08):

  • Continued discussion of graph coloring, planar graphs and the Four Color Theorem. Some links:
    • Vertex Coloring on MathWorld
    • Graph Coloring on Wikipedia
    • planar graphs on MathWorld
    • planar graphs on Wikipedia
    • the Four-Color Theorem on MathWorld
    • the Four-Color Theorem on Wikipedia

  • Discussed Rules of Inference, Direct Proofs and Indirect Proofs. Here are some notes on proof methods: proofs.shtml. These will notes will be expanded and updated over the next week or so.

• [Thu Feb 07 09:00 2008]
  Homework 2 posted.

• [Thu Feb 07 09:00 2008]
  Lecture 3 (2/5/08):

  • We finished the Three Missionaries and Three Cannibals problem.

  • Revisited Euler graphs:
    • If a multigraph G is not an Euler graph, we can always add edges to G to make it into an Euler graph. This is because the number of odd degree vertices in any graph must be even.
    • We cannot say the same for removing edges from a graph.

  • Began discussion of graph coloring and planar graphs.

• [Tue Feb 05 11:23 2008]
  Here is a source for many more Knights vs Knaves logic puzzles: link

• [Sat Feb 02 12:15 2008]
  A note on the "Three Jealous Girlfriends" problem in Homework 1;

  The graph you will construct is rather large. There are 7 things involved: 3 girlfriends, 3 boyfriends and 1 boat. If you allow each to be on either bank of the river, you would have 2^7 = 128 nodes. You can cut down the number of nodes by thinking about the problem this way:

  • If all 3 girls are on the same bank, then it doesn't matter where the boys are. (Why?) This gives us 8 nodes representing the situations where the 3 girls are on the original side and 8 nodes where the girls are on the far side.
  • If there is at least one girl on both each of the bank, then the boyfriends have to be on the same side of the river as their girlfriends. There are only 6 ways to do this.
  • That gives 8 + 8 + 6 = 22 nodes. We need to multiply by 2 for the possibility that the boat is on the near side or the far side of the river. So, your graph should have 44 nodes.

  That's a pretty big graph. You'll want a big piece of paper to draw on. It will get pretty messy.

  When this assignment gets graded, our TA Don Dimitroff will only spot check the graph. Instead, you should write down clearly is who is on the boat for each trip and who is on each bank of the river after each trip.

  Final hint: the shortest solution I found involved 11 trips.

• [Fri Feb 01 16:10 2008]
  Lecture 2 (1/31/08):

  • There are numerous descriptions of the Seven Bridges of Konigsberg problem on the web. Here are ones from Wolfram's MathWorld and Wikipedia.

  • The definitions page has definitions of graph, circuit, Euler Graph and degree.

  • Here's a write up of problems similar to the Three Cannibals and Three Missionaries problem from The Mathematical Association of America.

• [Fri Feb 01 16:10 2008]
  Our TA Don Dimitroff's office hours are listed on the contacts page.

• [Fri Feb 01 13:00 2008]
  Lecture 1 (1/29/08): Don Dimitroff's Powerpoint slides on logic from the first class is available.

• [Thu Jan 31 11:15 2008]
  Homework 1 posted.

• [Tue Jan 22 15:30 2008]
  Added a definitions page for material not in the textbooks.

• [Mon Jan 21 16:00 2008]
  We will use the following textbooks in this section.

  • A Short Course on Discrete Mathematics by Edward A. Bender and S. Gill Williamson. Dover Publications, 2004. ISBN 0486439461. [link]

  • Mathematics for Algorithm and System Analysis by Edward A. Bender and S. Gill Williamson. Dover Publications, 2007. ISBN 0486442580. [link]

  Copies of these textbooks are available in the Campus Bookstore and also on the authors' web pages in PDF (follow the given links). Yes, this is legal, because the authors, not Dover Publications, hold the copyright to these textbooks. If you intend to read the textbook on paper, I highly recommend that you buy printed copies since it will likely cost you more to print the PDF files. The list price of the textbooks are $14.95 each.

• [Mon Jan 21 16:00 2008]
  The course description and syllabus are available in PDF: description.pdf, syllabus.pdf. Hard copies will be distributed on the first day of class.

• [Mon Jan 21 15:40 2008]
  The first quiz is on Tuesday, February 26. Mark your calendars with the dates of the in-class quizzes and exams from the syllabus!

• [Mon Jan 21 15:37 2008]
  Web page up.