UNIVERSITY OF MINNESOTA 
SCHOOL OF MATHEMATICS

Math 4707: Introduction to combinatorics and graph theory

Fall 2020
(all online)


Prerequisites: Math 2243 and either Math 2283 or 3283 (or their equivalent).
Students will be expected to know some calculus and linear algebra,
as well as having some familiarity with proof techniques, such as mathematical induction.  
Instructor: Victor Reiner (he/him/his; Call me "Vic"). 
( Office: Vincent Hall 256, but I won't be there this semester! )
E-mail: reiner@math.umn.edu 
Classes: Mon-Wed 2:30-4:25pm via this Zoom ID.
Lectures are synchronous at the above class time, recorded, and posted to YouTube.
Please attend the synchronous Zoom lectures, with cameras on, whenever possible.
Office hours: Tues-Thur 9:05-9:55am at the same Zoom ID.
plus the last 25 minuutes of each lecture (Mon-Wed 4:00-4:25).
To facilitate interactions, we are experimenting with a gather.town meeting room, password given in lecture.
and Megan Smet set up a Discord server for us.
Required text: Discrete Mathematics: elementary and beyond, by Lovasz, Pelikan, and Vesztergombi (2003, Springer-Verlag).
One can download a free PostScript version of the book here, but it is not quite the final version of the book that we are using.
Course content: This is a course in discrete mathematics, emphasizing both techniques of
enumeration (as in Math 5705) as well as graph theory and optimization (as in Math 5707),
but with somewhat less depth than in either of Math 5705 or 5707.
We plan to cover most of the above text, skipping Chapters 6, 14, 15.
We will also supplement the text with some outside material.
Group work: Occasionally some course material will be taught by having the students
work together in small groups cooperatively, and students will be asked to explain their group's answer.
Here are some relevant handouts for these exercises:
Other useful texts
Title Author(s), Publ. info Access
Applied Combinatorics Keller and Trotter free download
Generatingfunctionology H. Wilf, AK Peters 2006 free download
Foundations of Combinatorics with Applications Bender and Williamson, Dover 2006 free download
Graph theory with applications Bondy and Murty free download (out of print)
Invitation to Discrete Mathematics Matousek and Nesetril, Oxford 1998 (not free; booksellers)
Applied combinatorics A. Tucker, Wiley & Sons 2004 (not free; booksellers)
Introduction to graph theory D. West, Prentice Hall 1996 (not free; booksellers)
Supplementary materials:
Homework,
exams,
grading:
There will be 5 homework assignments due usually every other week,
submitted and returned through the course Canvas page, however
  • 2 weeks where there will be a week-long take-home midterm exam,
  • a week at the end with a week-long take-home final exam.
Tentative dates for the assignments and exams are in the schedule below.

I encourage collaboration on the homework, as long as each person understands the solutions,
writes them up in their own words, and indicates on the homework page their collaborators.

The take-home midterms and final exam are open-book, open-library, open-web,
but in contrast to the homework on exams, no collaboration or consultation of human sources is allowed.

Late homework will not be accepted.
Homework solutions should be well-explained
-- the grader is told not to give credit for an unsupported answer.
Complaints about the grading should be brought to me.

Grading scheme :
  • Homework = 40% of grade
  • Each of 2 midterms = 20% of grade
  • Final exam = 20% of grade
Tentative HW assignments
and exam dates
Assignment or Exam Due date Problems from Lovasz-Pelikan-Vesztergombi text,
unless otherwise specified
Lecture notes Lecture videos
Homework 1 Wed
Sept 30
1.8 # 10,12,14,17,13,21,24,26,27
2.5 # 1,3,4(a),5,7,8
3.8 # 4,9

Out of 40 points,
median was 36,
mean 32.5, std deviation 9.8
Notes Batch 1
Notes Batch 2
Notes Batch 3
Sept. 9 Part1, Part2
Sept. 14 Part1, Part2
Sept. 16 Part1 (no Part 2 that day; group work on Poker hand probabilities)
Sept. 21 Part1, Part2
Sept. 23 (asynchronous) Part1, Part2
Sept. 28 Part1, Part2
Sept. 30 Part1, Part2
Homework 2 Wed
Oct 14
1.8 # 33
3.8 # 8,11,12
4.3 # 5,8,9(a,b),11,12

Out of 40 points,
median was 37.5,
mean 33.2, std deviation 10.6
Notes Batch 4
Notes Batch 5
Oct. 5 Part1, Part2
Oct. 7 Part1, Part2
(Oct. 12 had no video-- group work with
handout on Stirling numbers of the 2nd kind)
Oct. 14 Part1, Part2
Oct. 19 Part1, Part2
Oct. 21 Part1, Part2
Exam 1 Wed
Oct 21
Here is Midterm 1
to be handed in at the course Canvas site.

Out of 100 points,
median was 98,
mean 93, std deviation 8
Homework 3 Wed
Nov 4
7.3# 4,5,9,10,13
8.5# 2,3,4,5,7,9,11
In this homework, assume graphs are simple,
that is, with no parallel/multiple edges nor self-loops.
In problem 7.3.4, only draw one example of
each such graph, up to isomorphism.

Out of 40 points,
median was 37,
mean 36, std deviation 3.5
Notes Batch 6
Notes Batch 7

Oct. 26 Part1, Part2
Oct. 28 Part1, Part2
Nov. 2 Part1, Part2
Nov. 4 Part1, Part2
Nov. 9 Part1, Part2
Nov. 11 Part1, Part2
Homework 4 Wed
Nov 18
9.2# 3, 7
10.4# 5,6,11,13(a,b),15
In 10.4.11, the graph should have 2^3=8 vertices,
and assume they mean a pair of subsets forms an
edge exactly when one is a subset of the other,
and their cardinality differs by one, e.g. {a} and {a,c}.

Out of 40 points,
median was 37,
mean 35, std deviation 8
Notes Batch 8 Nov. 16 Part1, Part2
Nov. 18 Part1, Part2
Exam 2 Wed
Nov 25
Here is Midterm 2
to be handed in at the course Canvas site.

Out of 100 points,
median was 85,
mean 81, std deviation 14
Homework 5 Wed
Dec 9
10.4 # 7
12.3 # 1, 2, 5, 6
13.4 # 1, 2, 7, 8, 9(a)
Correct the hypotheses of 12.3.6 by assuming also
that every vertex has degree 3. And here is a
hint for 12.3.5: first note that the Petersen graph
has no cycles shorter than 5-cycles.

Out of 40 points,
median was 35,
mean 33, std deviation 8.5
Notes Batch 9
Notes Batch 10
Notes Batch 11
Notes Batch 12
Nov. 23 Part1, Part2
Nov. 25 Part1, Part2
Nov. 30 Part1, Part2
Dec. 2 Part1, Part2
Dec. 7 Part1, Part2
Dec. 9 Part1, Part2
Dec. 14 Part1, Part2
Dec. 16 Part1, Part2
Final Exam Wed
Dec 16
Here is the final exam
to be handed in at the course Canvas site.

Out of 100 points,
median was 91,
mean 89.5, std deviation 9.3
Back to Reiner's Homepage.