## Combinatorics

#### Math 450 Fall 2007 Section 001

Announcements:
(Dec 19) I have finished grading the final exam and computing the final grades. Both have been uploaded to Blackboard, and I will submit the official grades today.
Thanks for your hard work this semester! I enjoyed teaching the class. Enjoy the holiday break!

Course Materials:
Course policies and course log recording topics covered in each lecture.
Textbook: Introductory Combinatorics by Richard A. Brualdi, Pearson Prentice Hall, fourth edition, 2004. (errata for the 4th edition)

Homework:
 homework #1, due Wed Sept 5 homework #2, due Wed Sept 12 homework #3, due Wed Sept 19 homework #4, due Wed Sept 26 homework #5, not to be submitted homework #6, due Wed Oct 10 homework #7, due Wed Oct 17 homework #8, due Fri Oct 26 homework #9, due Wed Nov 7 homework #10, due Wed Nov 14 homework #11, due Wed Nov 28 homework #12, due Wed Dec 12

Instructor:
Stephen Hartke, hartke @ No . Spam . únl . edu (appropriately changed)
Office: Avery Hall Room 339, Phone: 402-472-7001
Office Hours: Mon, Wed, Fri 1:00pm-2:00pm, or by appointment.
Meeting Times:
Mon, Wed, and Fri, 9:30am-10:20am, Avery Hall Room 118
Tests:
There will be 3 tests during regular class time: Fri Oct 5, Fri Nov 2, and Fri Dec 7.
Final Exam:
Tues, Dec 18, 10:00am-12:00pm Avery Hall Room 118

Old Announcements:
(Dec 15) I have graded homework 12; here is a complete solution. I plan to be in my office on Mon Dec 17 during the afternoon (between noon and 4pm), and you can pick up your homeworks then. If you are planning to come and ask questions, it is helpful if you email me specifically when you are coming so I can insure that I'm there.
(Dec 10) As announced in class, if your lowest test score is less than your final score (as percentages), then the weight of the test score will be reduced to 3% and the final increased to 37% when computing the final score. Grades so far have been computed and recorded in Blackboard. Please notify me if there are any inaccuracies.
(Oct 26) The second test will be Friday Nov 2 during class. The format will be similar to the first test. The test will cover Chapter 7, Section 8.1, and the part of Section 8.2 on the Stirling numbers of the second kind. 8.6.12 and 8.6.15 are useful exercises for reviewing the Stirling numbers.
(Oct 24) A handout on the Twelvefold Way summarizing the discussion in class.
(Oct 24) Thanks to everyone who filled out the informal feedback survey! Here is a summary of the feeback.
(Oct 1) Herb Wilf's book generatingfunctionology can be freely downloaded from his website.
(Oct 10) Homework #7 had a typo on the version distributed in class. Question 2 should be 7.8.28. The corrected version is posted below.
(Oct 9) Homework #6, Question 4, 7.8.13: 7.8.13 is not a linear recurrence relation, and so the methods we know so far do not apply. The recurrence can be solved by writing out a few terms and guessing, and then verifying the solution. As we have not covered other methods to solve this type of recurrence relation, 7.8.13 will be extra credit, and Question 4 on HW 6 will just consist of 7.8.15.
(Sept 28) Calculator policy for the tests: You may have any calculator for the test, but you may only use the six basic operations: add, subtract, multiply, divide, exponentiate, and logarithm. You will be required to sign a statement saying that you understand and agree to this policy and that you understand any infraction will result in a zero for the test grade.
(Sept 26) The revised Homework #5 is posted below.
(Sept 10) William Feller's article on Stirling's Formula (and correction).
(Aug 31) Question 3 on Homework 1 had a missing hypothesis: prove that a tiling cannot exist when n is odd and a multiple of 3. The updated homework sheet is below; refresh your web browser's cache if you're not getting an updated version. You can do the other cases for extra credit.
(Aug 29) Worksheet 1 developing the counting formulas for fundamental objects described in Chapter 3.
(Aug 27) Initial survey distributed on the first day of class.