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MATH 239Introduction to Combinatorics

Units
0.50
Faculty
Mathematics
Subject
Mathematics

When it runs

  1. F24
  2. W25
  3. S25
  4. F25
  5. W26
  6. S26
  7. F26
  8. W27
  9. S27

Ran in 7 of the last 7 terms. Winter 2027: scheduled, 5 lecture sections. Spring 2027: schedule not out yet.

Introduction to graph theory: colourings, matchings, connectivity, planarity. Introduction to combinatorial analysis: generating series, recurrence relations, binary strings, plane trees.

Prerequisites

  • Complete 1 of the following
    • Complete all of the following
      • Complete 1 of the following
        • Must have completed the following:
          • MATH145 - Algebra (Advanced Level) (0.50)
        • Earned a minimum grade of 60% in each of the following:
          • MATH135 - Algebra for Honours Mathematics (0.50)
      • Complete 1 of the following
        • Must have completed at least 1 of the following:
          • MATH136 - Linear Algebra 1 for Honours Mathematics (0.50)
          • MATH146 - Linear Algebra 1 (Advanced Level) (0.50)
        • Earned a minimum grade of 70% in each of the following:
          • MATH106 - Applied Linear Algebra 1 (0.50)
      • Complete 1 of the following
    • Complete all of the following

Antirequisites

  • Not completed nor concurrently enrolled in any of the following:
    • MATH229 - Introduction to Combinatorics (Non-Specialist Level) (0.50)
    • MATH249 - Introduction to Combinatorics (Advanced Level) (0.50)

Leads to

Fall 2026 sections

Enrolment from UW Open Data, which can trail Quest by up to two days. Instructors and rooms: Schedule of Classes.
SectionClassEnrolledMeets
LEC 0015948105 / 115MWF 13:30–14:20
LEC 0025949102 / 115MWF 08:30–09:20
LEC 003644346 / 115MWF 16:30–17:20
LEC 004644463 / 115MWF 15:30–16:20
TUT 1016439105 / 115M 15:30–16:20
TUT 1026440102 / 115M 16:30–17:20
TUT 103644146 / 115T 13:30–14:20
TUT 104644263 / 115M 14:30–15:20
TST 2016445316 / 460Oct 27 16:30–18:20

Winter 2027 sections

Enrolment from UW Open Data, which can trail Quest by up to two days. Instructors and rooms: Schedule of Classes.
SectionClassEnrolledMeets
LEC 00156710 / 150MWF 11:30–12:20
LEC 00256720 / 150MWF 08:30–09:20
LEC 00358070 / 120Online or by arrangement
LEC 7012258168 / 9999Online or by arrangement
LEC 702796832 / 9999Online or by arrangement
TUT 10156730 / 150W 15:30–16:20
TUT 10256740 / 150F 14:30–15:20
TST 20156780 / 300Mar 2 16:30–18:20

Resources

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Reviewed on UW Flow

77% liked it31% easy78% useful

From 854 ratings and 194 comments on UW Flow. The most helpful comments, quoted as written, without names. Read them all on UW Flow.

  • The course is way overhated. It's not bad at all. It's split up into two parts, enumeration and graph theory. There are only a couple types of questions they ask for enumeration and only around 15ish theorems in graph theory. Here's how to do well:
    Enumeration:
    - Bijections
    Probably the hardest part of the course. Your best bet is to do as many counting proofs in the notes and follow proper notation. The bijections they ask on the midterm/final are easy to spot, but much harder on the assignments. Once you know the idea, just formalize using set notation according to the notes and you'll do well.
    - Negative Binomial Theorem / Binomial Theorem
    I think they give proofs for these in the…

    Apr 2024 · liked it · 10 found this helpfulOn UW FlowRemove this

  • Just a disclaimer: I took this course in Spring 2021 with Ashwin Nayak, Chelweon Heo, Olya Mandelshtam and Jorn Van Der Pol - pray you never have to go through what my term-mates and I had to. This was easily and by far the absolute worst course I have ever taken at Waterloo, with the worst professors I ever had the displeasure of interacting with.
    The words arrogant, cold, and ignorant come to mind when I recall interacting with the professors for the most basic help during Office Hours, which were the only time we could contact these people as they abandoned Piazza for the first half of the course, only returning once half the class failed their "test", which was essentially a midterm…

    Oct 2021 · didn’t like it · 4 found this helpfulOn UW FlowRemove this

  • Good news and bad news. Good news: the graph theory part is hard, but survivable. Bad news: the enumeration part is 10x harder and barely survivable. This course is the hardest course as of 2B, and the enumeration part is about as useless as chaos theory (and about as hard too). Did I mention this course was hard?

    Jul 2022 · didn’t like it · 3 found this helpfulOn UW FlowRemove this

  • bird

    Aug 2025 · liked it · 2 found this helpfulOn UW FlowRemove this

  • For enumeration, focus on bijections, binomial theorems, compositions, binary strings, and recurrence relations. In graph theory, memorise key theorems and apply them, especially for longest path proofs, cycles, trees, planar graphs, and colouring problems. If one practices consistently, this course should be straightforward and enjoyable.

    Aug 2024 · liked it · 2 found this helpfulOn UW FlowRemove this

Discussed on r/uwaterloo

2,418 posts and comments in 1,525 threads mention MATH 239, February 2011 to December 2024. Quoted word for word, newest first; each reply sits under the post and the comment that started its branch. Search r/uwaterloo for newer posts.

Fall 2024

Taking Math 128 as Math Major? 4 points, 5 comments

“I was wondering if taking math 128 as a math major would negatively impact me for my future courses. I heard it's fine for cs majors but didn't find much info for Math majors. …”

u/Laeriana: “… (one notable exception being Mathematical Studies, which can require MATH 207 instead or MATH 229/239/249). Which programs were you looking into at the moment? …”

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MATH239 Retaking 9 points, 14 comments

u/Own-Lake3270: “Hey 239 marks came out tday i got a 50-59% on it should i retake for a higher mark?? Im in math planning on majoring in CNO”

u/Imaginary_Record_752: “just say u got 51% bro”

u/amsyed10385: “i dont think either co342 or 330 (continuations of math 239 content) required 60% in 239. That being said, those 2 courses are quite hard so one might struggle a lot if they did get 60’s or less in 239”

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Math 138 or Math 128 6 points, 5 comments

“Im a math/bba double degree and am desperate need for help. I passed math 137 but didn’t get the 60+ requirement to progress to math 138. …”

u/123448account: “… If you aren’t able to get that you could take math 239 to satisfy the requirement or retake math 128. …”

u/Tutelina: “if I remember correctly, math 239 has a required mark earned from math 137 ...”

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Bad CS student needing advice on doing math research and double majoring? 1 point, 2 comments

u/Efficient_Throat_920: “… The problem is I have a 74% average because I failed/did terribly in some CS courses but I got around a 90 average in MATH235/237/239 (but haven’t done anything past that), and I worry that I am not going to be able to get any professors to give me research opportunities or get …”

u/amsyed10385: “… So if you liked math 239, math 235, cs 341, I think that is probably a good indicator you may like CO”

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Will I survive if I take these courses in a term 1 point, 4 comments

“I’m considering taking stat231, actsc231, co370, cs330 in the winter term. How difficult are these courses?”

u/Breadfruit-Turbulent: “… It felt like an extension to co250 and math 239. Like taking what you learnt and apply it differently I took cs 330 but can’t really tell you what I learnt. A bunch of memorisation and bs. I believe my final was open book and mc. …”

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2B CS course selection 2 points, 3 comments

u/Standard-Lecture-950: “As of now, these are the classes I am enrolled into: \- CS 245, 246, Math 239, Stat 231 and an elective Could someone walk me through how the term would look like if i go ahead with this option? …”

u/iamanaybaid555: “Your best combination would be: • CS 246 (pre-requisite for CS 241 and CS 240) • CS 251 (pre-requisite for CS 350) • MATH 239 (pre-requisite for CS 341) • CS 245 (pre-requisite for CS 240) • One elective Two reasons for not taking 231 with this would be a heavier workload and no …”

u/Howardwang0315: “I took CS245 246 MATH239 STAT231 for 2A and i think if you can get a coop in cycle1 or 2then you can do it well, but if you can't do it like me, then it may be kind of hard.”

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STAT 333 for 2B 5 points, 2 comments

u/serenelmuss314: “… Having completed Math 235/237/239, STAT 230 and another CS course in 2A, I am currently thinking of taking STAT 231, STAT 333, ACTSCI 231, PSYCH 101 for 2B (I have a few credit transfer so taking less than 5 courses for a few term is okay). …”

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Check it elsewhere for Fall 2026

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