CPSC 221: Discrete Structures

     Department of Mathematics and Computer Science
     Hobart and William Smith Colleges

     Spring, 1998.

     Instructor:  David J. Eck.

     Monday, Wednesday, Friday, 2:40--3:50 PM, in Room Lansing 300.

The Course and the Text

CPSC 221 is a course in discrete mathematics. The term "discrete" here is used to distinguish this branch of mathematics from calculus and analysis, which deal with the real numbers and with continuous functions. Areas of mathematics that we will touch on include logic, set theory, combinatorics, and graph theory. These topics have wide-ranging applications in computer science and in other branches of mathematics.

The course will emphasize mathematical reasoning and proof techniques. Although CPSC 221 is listed as a computer science course and is a required course in the computer science major, it is not a course in programming. We will not use computers. (Occasionally, I might give you the option of writing a computer program as a substitute for some homework exercises.)

The text for this course is Discrete Mathematics and its Applications, third edition, by Kenneth H. Rosen. This is a big book, and we will only do a fraction of the material in it. I expect to cover most of the "core sections," as listed on page xvii. I hope to be able to cover a few additional sections, depending on how things go.

Homework Assignments

I will assign homework and collect it every week. But you should understand that I cannot possibly grade as many problems as you need to do! Answers to the odd numbered exercises are given at the back of the text. I advise you to do as many exercises as you can from each section that we cover. Remember that you are expected to spend ten hours or more per week on this course, outside of class.

Homework exercises will be graded on the basis of the work you show. No credit will ever be given for an unsupported answer. I expect you to write up your answers clearly and neatly. Most of the exercises will be proofs. Proofs are written in English prose, with some mathematics added in. You should write them with the same care that you would devote to an essay in an English class.

Getting Help

I encourage you not to be shy about asking for help! Come to my office when you need help with the course material or with your homework. The "math intern," Lynn Robitaille, can also offer help with the course. And if you find that you need even more help than she and I can give, you can ask Lynn to set you up with a tutor.


There will be two in-class tests, which will be given on Friday, April 24 and on Wednesday, May 20. There will also be a cumulative final exam, which will be given during the regularly scheduled final examination period, at 1:30 on Wednesday, June 10. The final exam will be in our regular classroom.


Your numerical grade for the course will be determined as follows:

             First Test:               25%
             Second Test:              25%
             Final Exam:               30%
             Homework:                 20%

My scale for converting numerical grades into letter grades is:

             A:  90% to 100%
             B:  80% to 89%
             C:  65% to 79%
             D:  50% to 64%
             F:  less than 50%

Grades near the bottom or top of a range are modified by a minus or plus. I follow this scale fairly strictly, although I occasionally "curve" a test by adding some points to each person's score, if I judge that the original grades on the test do not accurately reflect the performance of students in the class.

Office Hours, Email

My office is room 301 in Lansing Hall, just next door to our regular classroom. My office phone extension is 3398. I am on campus most days, and you are welcome to come in anytime you can find me there. I will announce office hours and post them on my office door as soon as my schedule is determined, but note that your office visits are not restricted to my regular office hours.

My email address is ECK. Email is good way to communicate with me, since I usually answer messages within a day after I receive them.

David Eck, 25 March 1998