Math 315: Applied Combinatorics

Fall 2017



Date Lecture Notes
Week 1
8/28 Introduction to the course; the Pigeon-Hole Principle  
8/30 The Generalized Pigeon-Hole Principle; the Erdős–Szekeres Theorem
Week 2
9/4 Labor Day
9/6 The Method of Mathematical Induction: weak and strong induction
Week 3
9/11 Permutations, strings over a finite alphabet, and choice problems; binomial coefficients and Pascal's Triangle notes
9/13 Combinatorial proofs of binomial identities (hockey stick, Vandermonde); the Binomial Theorem notes
Week 4
9/18 Multinomial coefficients and the Multinomial Theorem; distributing objects into boxes (distinct vs. identical) notes
9/20 Stars and bars: weak compositions and compositions; set partitions and Stirling numbers of the second kind notes
Week 5
9/25 Stirling numbers of the second kind, Bell numbers, counting surjections; integer partitions notes
9/27 Ferrers diagrams, conjugate and self-conjugate partitions; introduction to cycles in permutations notes
Week 6
10/2 Cycles in permutations; decomposition of a permutation into disjoint cycles notes
10/4 Midterm 1
Week 7
10/9 Permutations with a restricted cycle structure; Stirling numbers of the first kind
10/11 The Sieve: the Principle of Inclusion-Exclusion
Week 8
10/16 Derangments, Hat Check Problem, Ballot Sequences notes
10/18 Ballot Sequences, Catalan Numbers, Tower of Hanoi, Intro to Generating Functions
Week 9
10/23 Using Generating Functions to solve recurrences, Fibonnacci Numbers notes
10/25 Generating Functions notes
Week 10
10/30 Triangulations of an n-gon
11/1 Solving the Catalan generating function; Newton's Binomial Theorem and a closed formula for the Catalan numbers
Week 11
11/6 Motzkin Numbers Example
11/8 Products and compositions of generating functions; introduction to exponential generating functions
Week 12
11/13 Exponential generating functions and recurrence relations; review for Midterm 2
11/15 Midterm 2
Week 13
11/21 Products of exponential generating functions
11/22 THANKSGIVING Break
Week 14
11/27 Compositions of exponential generating functions (set partitions, committees with chairpersons)
11/29 Subsequence conditions on permutations: pattern avoidance
Week 15
12/4 Permutations avoiding a pattern of length three; the Catalan numbers again
12/6 Stack sortable permutations and 231-avoidance
Week 16
12/11 Two stacks in series; review for the final exam
12/18 Final Exam (3PM)