Math 386: Combinatorics: Schedule

Fall 2022
Tom Zaslavsky


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Secret code:   § = section,   ¶ = paragraph.
Doubling the symbol means plural.
Boldface problem numbers on hand-in homeworks are the ones that were graded.
Asterisked* problems are bonus problems that were graded but not required.
## 8-10(a) means part (a) of each of 8, 9, and 10. ## 8, 10(a) means all of # 8 and part (a) of # 10.

Date Reading & Study Topics Homework exercises
for discussion on
Hand in on Notes
#1
W 8/24 –
M 8/29
Ch. 1 except
§§1.3, 1.5
Samples of
combinatorics
W 8/24: The points-lines problem.
F 8/26: Ch. 1, ## 1, 4(a), 10.
M 8/29: Ch. 1, ## 13, 15, 22.
HW 1, W 8/31:
Ch. 1, ## 2, 3, 4(b), 7, 11, 14, 24, 25, 29, (37 optional).
#2
W 8/31 – "M" 9/6
(Tu is "M"!)
Ch. 2:
§1 (for 8/31),
§§2–3 (9/2),
§§4–6 (9/6)
Counting
  principles;
Permutations &
  combinations;
Multisets
"M" 9/6: Ch. 2, ## 1–3, 4(a), 7, 11, 12, 17 (work on these problems before 9/6 and bring questions and answers to the class).
W 9/7: ## 21, 28(a), 34.
HW 2, F 9/9:
Ch. 2, ## 4(b,c), 8, 9, 16, 20, 22, 39(a-c), 41, 56.
#3
F 9/9 –
W 9/14
Ch. 3, §§1–2 (9/9), §3 (9/12) Pigeonhole
  Principle;
Ramsey theory
W 9/14: Ch. 3, ## 1, 2, 7, 9, 14, 19(a). HW 3, F 9/16:
Ch. 2, ## 28(b), 32, 40;
Ch. 3, ## 1, 5, 6, 10, 19(b,c).
#4
F 9/16 –
W 9/21
Ch. 4, §§1–2, 5 More about
permutations;
Partially ordered sets
W 9/21: Ch. 3, # 26;
Ch. 4, ## 1, 2, 6-8(a), 36, 37, 38, 42, 48.
HW 4, F 9/23:
Ch. 3, # 27; III #3;
Ch. 4, ## 6-8(b), 8(c), 10, 39, 43, 45, 47.
Problems "III": see announcements page.
Note correction to #39.
We'll discuss 39, 47, et al. in class.
#5
F 9/23 –
  M 10/3
Ch. 5, all
(§6 for 9/30);
permutation patterns
Binomial coefficients;
Partially ordered sets
M 10/3: Ch. 5, ## 3, 7, 10, 19, 30, 35, 39, III #4, III #6 (work on these problems before 10/3 and bring questions and answers to the class). HW 5, F 10/7: Ch. 5, ## 6, 8, 11, 13, 16, 20, 23, 25, 32*, 33, III #5, III #7*. Click to hear what change ringing sounds like.
Postpone the proofs of Theorems 5.6.1 and 5.6.2 until later.
F 10/7 Homework review HW ##1–5 Any problems you have questions about, including Newton's binomial theorem.
#6
M 10/10 –
  M 10/17
Ch. 6, §§1-5
10/10: §§1-2
10/12: §§3-5
Principle of Inclusion and Exclusion F 10/14: Ch. 6, ## 1, 3, 4, 7, 11, 17, 21, 24(a). HW 6, M 10/17:
Ch. 6, ## 5, 9, 10, 13, 14, 16, 26, 33.
Warning about Thm. 5.5.1 and hints for Ch. 6, #40 (on the announcements page).
W 10/19 Review class Everything we've done up to §6.4 Omit § 5.6.
M 10/24 Midterm Test I Everything we've done up to §6.4 Omit §5.6.
#7
W 10/26 – F 10/28
§6.5 Permutations with restricted relations F 10/26: Ch. 6, ## 27, 30, 32. HW 7, M 10/31: Ch. 6, ## 28, 29, 31.
#8
F 10/28 – M 11/7
§§4.5, 5.6, 6.6 (omit pp. 195-198) Partially ordered sets;
Möbius inversion
Before M 10/31, practice computing Möbius functions: # III.10. W 11/2, DO IT: # III.10.
M 11/7: Ch. 4, # 47;
Ch. 6, ## 34, 36, 37.
Hint for # 34: Use the matrix interpretation.
HW 8, W 11/9:
Ch. 4, ## 48, 50;
Ch. 6, ## 35, 38(Π34), 40.
Tests will only have simple questions about the Möbius function and Möbius inversion.
Read notes on matrices for Möbius function and inversion.
Note correction to Ch. 4, #50.
#9
W 11/9 –
M 11/14
§§7.1–7.2 Number sequences;
Generating functions
M 11/14: Ch. 7, ## 1(a,c), 2, 3(b), 4, 8. HW 9, W 11/16:
Ch. 7, ## 1(d), 2, 3(c), 5, 6, 9, 10, 11.
#10
W 11/16 – M 11/21
§§7.4–5 Linear recurrence relations M 11/21: Ch. 7, ## 13(a-c), 14(b,d), 15, 17, 19, 22, 31, 33, 42. HW 10, M 11/28:
Ch. 7, ## 13(e), 14(a,c,e), 18, 20, 34, 35, 44, 45.
Linear r.r. have two solution methods. One uses g.f., the other does not. Learn both!
See "Supplements" to Section 7.5, for non-homogeneous recurrence relations of the kind in §7.5.
Corrections for p. 245 and p. 246.
M 11/28 Review class Everything we've done since Midterm I; and everything on posets.
W 11/30 Midterm Test II Everything we've done since Midterm I; and everything on posets.
#11
F 12/2 –
W 12/7
§§10.1, 10.4 Latin squares M 12/5: Ch. 10, ## 10, 12, 17(a,c), 41, 42. HW 11 (or "12"), W 12/7: Ch. 10, ## 11, 13, 17(d,f), 43. §10.1: Omit GCD's, except easy ones like gcd(4,10).
Omit the block designs on pp. 381–384.
#12
W 12/7 –
F 12/9
§10.4 Affine planes F 12/9: Ch. 10, ## 44, 52, 54, 61.     —  
   

M 12/12     —  
FINAL EXAM
5:40–7:40 p.m. in CW 107   Comprehensive; but no Latin rectangles. (Expect P.I.E.)


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