Math 28: Introduction to Combinatorics

Winter 2020


  • The latest homework will always appear on top.

  • If you are interested in learning to typeset mathematics here is a list of resources compiled by Rebecca Weber on LaTex

    Homework assignments

  • Late Homework will not be accepted. In order to qualify for a regrade you must have submitted your homework on the due date.
  • Write the names of your the group members with whom you worked on the homework, please make sure that what you turned in for homework is your own understanding of how to do the problems.

    Practice problems: These problems are very important. We will discuss these in class as a group. Please be sure that you understand these problems thoroughly as you will be asked to present some of these problems in class.

    Graded assignments: These problems will graded in detail.

    Homework due day: Homework will be assigned daily and will be collected once a week.

    Week 9
    Thursday, March 5:
    • Topic: In-class work on Inclusion-Exclusion.
    • All the problems: Problem Set
    Wednesday, March 4:
    • Topic: Summary Lecture on Generating Functions
    • All the problems: Problem Set
    Tuesday, March 3:
    • Topic: Inclusion-Exclusion
    • Problem Set: Problem Set
    • In-class problems: # 169, 173, 174, 175
    • Graded problems (will not be collected): # 167, 168, 170, 171, 172
    Week 8
    Thursday, February 27:
    • Topic: Generating Functions
    • All the problems: Problem Set
    • In-class problems: # 159, 161, 163, 164, 165,
    • Graded problems (Due Thursday, March 5): # 157, 158, 160, 162, 166
    Wednesday, February 26:
    Tuesday, February 25:
    • Topic: Exam # 2
    • Problem Set: Problem Set
    • In-class problems: # 149, 150, 156
    • Graded problems (Due Thursday, March 5): # 151, 152, 153, 154, 155
    Week 7
    Thursday, February 20:
    • Topic: Applications of Generating Functions to partitions of numbers and solving recurrences
    • Slides for today: Applications of Generating Functions
    • All the problems: Problem Set
    • In-class problems: # 149, 150, 156,
    • Graded problems (Due Thursday, March 5): The problems for today will be due the 9th week!
      # 151, 152, 153, 154, 155
    Wednesday, February 19:
    • Topic: Partition of numbers and Review for Midterm # 2
    • All the problems: Problem Set
    Tuesday, February 18:
    • Topic: Generating Functions and Counting
      Slides for in-class presentation: Intro to Generating Functions
    • Problem Set: Problem Set
    • In-class problems: # 135, 137, 138, 140, 141, 144, 147
    • Graded problems (Due Thursday, Feb. 27): # 136, 139, 142, 143, 145, 146, 148
    Week 6
    Thursday, February 13:
    • Topic: Stirling numbers and polynomials, partitions of integers
    • Slides for today: Distributions Part II
    • All the problems: Problem Set
    • In-class problems: # 124, 126, 129, 132
    • Graded problems (Due Thursday, Feb. 20): # 125, 127, 128, 130, 131, 133, 134
    Wednesday, February 12:
    • Topic: We will work on problems for due tomorrow and on problems from yesterday's class.
    Tuesday, February 11:
    • Topic: Distributions: functions, multisets, Stirling numbers
      Slides for in-class presentation: Distributions Part I
    • Problem Set: Problem Set
    • In-class problems: # 115, 116, 117, 119, 120, 121
    • Graded problems (Due Thursday, Feb. 20): # 112, 113, 114, 118, 122, 123,
    Week 5
    Thursday, February 6:
    • Topic: Introduction to Distributions
    • Slides for today: Twenty-Fold Way
    • All the problems: Problem Set
    • In-class problems: # 104, 107, 108, 109
    • Graded problems (Due Thursday, Feb. 13): # 101, 102, 103, 105, 106, 110, 111
    Wednesday, February 5:
    • Topic: We will work on problems for due tomorrow and on problems from yesterday's class.
    Tuesday, February 4:
    • Topic: Basics of Graph Theory
      Slides for in-class presentation: Intro to Graphs
    • Problem Set: Problem Set
    • In-class problems: # 91, 93, 97, 98, 99
    • Graded problems (Due Thursday, Feb. 13): # 90, 92, 94, 95, 96, 100
    Week 4
    Thursday, January 30:
    • Topic: Recursions and Intro to Graph Theory
    • Slides for today: Recursions
    • All the problems: Problem Set
    • In-class problems: # 81, 84, 85, 87, 88
    • Graded problems (Due Thursday, Feb. 6): # 80, 82, 83, 86, 89
    Wednesday, January 29:
    • Topic: We will work on problems for due tomorrow and on problems from yesterday's class.
    Tuesday, January 28:
    • Topic: Introduction to Induction - Induction proofs
      Slides for in-class presentation: The Principle of Mathematical Induction
    • Problem Set: Problem Set
    • In-class problems: # 67, 69, 70, 73, 75, 77, 78
    • Graded problems (Due Thursday, Feb. 6): # 68, 71, 72, 74, 76, 79
    Week 3
    Thursday, January 23:
    Wednesday, January 22:
    • Topic: We will work on problems for due tomorrow and on problems from yesterday's class.
    Tuesday, January 21:
    • Topic: Application of Binomial Coefficients: Lattice Paths and Catalan Paths
      Slides for in-class presentation: Lattice Paths and Catalan Paths
    • Problem Set: Problem Set
    • In-class problems: # 48, 49, 51, 53, 56
    • Graded problems (Due Thursday, Jan. 30): # 50, 52, 54, 55, 57
    Week 2
    Thursday, January 16:
    • Topic: The Quotient Principle
    • We work on problems related to the quotient principle
    • Slides for today: The Quotient Principle
    • All the problems: Problem Set
    • In-class problems: # 37, 38, 43, 45
    • Graded problems (Due Thursday, Jan. 23): # 39, 40, 41, 42, 44, 46, 47
    Wednesday, January 15:
    • Topic: We will work on problems for due tomorrow and on problems from yesterday's class.
    Tuesday, January 14:
    • Topic: Bijection Principles and the definition of Binomial Coefficient
      Slides for in-class presentation: Bijection Principle
    • Problem Set: Problem Set
    • In-class problems: # 25, 26, 28, 29, 30, 33, 34
    • Graded problems (Due Thursday, Jan. 23): # 27, 31, 32, 35, 36
    Week 1
    Thursday, January 9:
    • Topic: Difference Principles and Review Functions
    • We will continue introducing the basic counting principles and review terminology related to functions.
    • Slides for today: Subtraction Principle and Review of Functions
    • All the problems: Problem Set
    • In-class problems: # 12, 13, 15, 17, 21, 23
    • Graded problems (Due Thursday, Jan. 16): # 16, 18, 19, 20, 22, 24
    Wednesday, January 8:
    Tuesday, January 7:
    • Topic: Basic Set Notation and Intro to counting principles
    • Slides for today: Basic Set Notation and counting principles
    • Introduction to the course and basic notation. We will begin working on problems related to the Sum and Product Principles.
    • Read/Study: Slides on Set Notation and handouts on group work and proof writing all available in Canvas.
    • Group Work: Working together helps everyone
    • Problem Set: Problem Set
    • In-class problems: # 1, 3, 4, 5, 7, 8, 10
    • Graded problems (Due Thursday, Jan. 16): # 2, 6, 9, 11, 14,


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