Math 386: Combinatorics Announcements

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Tests

Test I (Oct. 7)

Covering the parts we've done so far in Chapters 1, 3, and 5 (that is, HW Sets I-VI). Grading guidelines:

 	A       B       C       D       F
	79-100	64-78	47-63	40-46	0-39

Test II (Dec. 2)

Covering Sections 5.4 (omit 5.5), 6.1-4 (omit the proof of the Principle of Inclusion and Exclusion), 4.5 and 5.7 (no proofs here), and 2.1-2 (excluding the Chinese Remainder Theorem). Grading guidelines:

	A       B       C       D	F
	80-100	61-79	41-60	33-40	0-32

Final Exam (Mon., Dec. 13)
The exam will be in room EB-Q23. (Allow plenty of time to find it.) The time is 11:00 a.m. - 1:00 p.m. I will allow an extra 15 minutes if possible. The exam will cover everything in the course, with some emphasis on Homework XIII (Section 5.6 and the assigned parts of Chapter 7) as well as Section 5.3 (Identities), including combinatorial proofs. No proofs from Sections 4.5 and 5.7 (partially ordered sets) and nothing from Section 5.5 (multinomial theorem). Grading guidelines:
```
	A       B       C       D       F
	118-150	91-117	63-90	51-62	0-50
```

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.
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 (mathematically) ``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 to Textbook

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!)