Math 386: Combinatorics Announcements

Tests

• Test I (Sept. 26)

  Covering the parts we've done so far in Chapters 1 and 3 (that is, HW Sets I-IV). Grading guidelines:

   	A       B       C       D       F
  	80-100	64-79	47-63	40-46	0-39
   

• Test II (Oct. 31)

  Covering Chapter 5 and Sections 6.1, 6.2 (that's HW Sets V-VIII). Grading guidelines:

  	A       B       C       D       F
  	82-100	65-81	49-64	42-48	0-41
  

• Test III (Dec. 5)

  Covering Homework Sets IX-XIII, i.e., Sections 6.2-4 (omit the proof of the Principle of Inclusion and Exclusion), 2.1-2 (except Application 6), 10.1 to page 373, and 10.4 to the middle of page 403 (except page 400 and the top of page 401). Grading guidelines:

  	A       B       C       D	F
  	85-100	70-84	54-69	47-53	0-46	
  

• Final Exam (Wed., Dec. 14)

  The exam will be in room S1-140. The time is 8:30 - 10:30 a.m. I will allow an extra 15 minutes. The exam will cover everything in the course (except the following: proof of inclusion/exclusion; projective planes; and general finite fields, F_n where n is a prime power but not a prime). Grading guidelines:

  	A       B       C       D       F
  	105-150	78-104	58-77	48-56	0-47
  

Mathspeak

Here are some tips on using English correctly and clearly in mathematics.

• To write "a divides b" or "a is a factor of b" as a formula, use a vertical bar: a|b .
• ``Unique'' has one and only one meaning in mathematics: ``unique'' = ``one and only one''. If you can't replace ``unique'' by ``one and only one'' in your writing, you're using it incorrectly.
  (N.B. In correct standard English, ``unique'' means ``of which there is only one'' or a closely related meaning -- see Oxford English Dictionary. It does not mean ``different''; if you mean that, say ``different'' or, in mathematics, ``distinct''.)
• ``Distinct'' means ``different from each other''.
• A definition is what tells you the meaning of a word or phrase. In math, you should be able to replace the word by its definition. If you can't, you are probably using it incorrectly. A definition is not in any way like a theorem, which is something that has to be proved.

Corrections and Additions to Textbook

• Here is a summary sheet (click!) of basic counting problems and formulas.
• Ch. 2, #16. It should also be assumed that acquaintanceship is symmetrical: i.e., if A is acquainted with B, then B is acquainted with A. (This isn't always so in real life!)
• In Section 6.3, p. 174, line 15, the expression (n-2)!D should be just (n-2)!.
• In the answers to Ch. 6, the last 3 problem numbers are 1 greater than they should be.