Discrete Mathematics I

Summer 2016


Instructors

Course Schedule

Topics

Final Exam and Requirements

Exercises

References

Course Progress
Image
(Images by Mike Sollami)

Instructors

Tibor Szabó Shagnik Das
Arnimallee 3, Rm 211a Arnimallee 3, Rm 204
szabo at math dot fu-berlin dot de shagnNOBOTSHEREik@mi.fu-berHAHAHAHAHAlin.de
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Course Schedule

Lectures will take place on Tuesdays and Wednesdays from 14:15 to 16:00 in Arnimallee 3, HS 001.

You have a choice of two exercise classes: Tuesdays, 16:15 to 18:00, in Takustraße 9, SR 049, or Wednesdays, 10:15 to 12:00, in Arnimallee 6, SR 025/026.
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Topics

The course will cover a selection from the following topics:

Enumerative Combinatorics

Elementary counting methods, double-counting, pigeonhole principle, recursions, generating functions, inclusion-exclusion, inversion, Polya theory

Discrete Structures

Graphs, set systems, designs, posets, matroids

Graph Theory

Trees, matchings, connectivity, planarity, colourings
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Final Exam and Requirements

Final Exam

The final (written) exam will be held in Hörsaal A, Henry-Ford-Bau, from 09:00 to 12:00 on the 26th of July.
A make-up exam will be offered in Hörsaal C, Henry-Ford-Bau, from 09:00 to 12:00 on the 12th of October.

Requirements

A full description of the formalities of the course and the requirements for successfully completing the course can be found here.
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Exercises

Homework assignments will be posted below, and should be submitted by the end of the Tuesday lectures. Alternatively, they may be submitted to the tutor box of Shagnik Das in Arnimallee 3.


Assignment Due date
Sheet 0 (warm-up) Not for submission
Sheet 1 (regarding the bonus) 26/4/2016
Sheet 2 (2/5/2016: lower bound on n added to Exercise 1) 3/5/2016
Sheet 3 (4/5/2016: characteristic polynomial in Exercise 5 corrected) 10/5/2016
Sheet 4 (11/5/2016: old exercise 3 promoted to Sheet 5) 17/5/2016
Sheet 5 (20/5/2016: clarification added to exercise 4) 24/5/2016
Sheet 6 (29/5/2016: footnote numbering corrected) 31/5/2016
Sheet 7 (3/6/2016: added examples for exercise 1) 7/6/2016
Sheet 8 (9/6/2016: typo in exercise 1(b) corrected) 14/6/2016
Sheet 9 21/6/2016
Sheet 10 (24/6/2016: connectedness condition added to exercise 6) 28/6/2016
Sheet 11 (1/7/2016: worst-case clarification added to exercise 5) 5/7/2016
Sheet 12 12/7/2016
Bonus Sheet 19/7/2016
Practice Sheet (Solutions [7/10/2016: Solution to 5a corrected]) Not for submission
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References

The following texts cover most of the material from this course.


M. Aigner Discrete Mathematics (German and English editions)
M. Bóna A Walk Through Combinatorics
R. Brualdi Introductory Combinatorics
R. Diestel Graph Theory, 4th edition
L. Lovász, J. Pelikán, K. Vesztergombi Discrete Mathematics, Elementary and beyond
J. Matousek, J. Nesetril Invitation to Discrete Mathematics (German and English editions)
D. West Graph Theory

To learn more about the subject, we recommend the following sources.


M. Aigner A Course in Enumeration
B. Bollobás Combinatorics
S. Jukna Extremal Combinatorics
A. Tucker Applied Combinatorics
H. Wilf Generatingfunctionology

Some notes are available below.


Elementary counting principles
The binomial theorem and combinatorial proofs
The twelvefold ways of counting
Generating functions I
Assorted notes on generating functions
Generating functions II (Updated version; typo at the bottom of page 4: should be cn-1, not cn)
Asymptotic estimates
Estimating binomial coefficients (originally written for Extremal Combinatorics)
The Inclusion-Exclusion principle (10/6/2016: updated)
Posets (14/6/2016: updated)
Möbius inversion
Examples of Möbius inversion
The pigeonhole principle and Ramsey's theorem
Basics of graph theory
Bipartite, connected and Eulerian graphs
Extremal problems
Trees
Matchings
Connectivity (Note: Inequality in Proposition on p1 should be reversed)
Coloring and planar graphs

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Course Progress


Week

Topics

References

1 Elementary counting principles: sum and product rules, double-counting, combinatorial proofs, binomial identities Ai Ch 1.1; Bó Ch 3-4; MN Ch 3.1-3
2 Twelvefold ways of counting; set partitions, Stirling numbers of the second kind, polynomial bases; permutations and cycles, Stirling numbers of the first kind Ai Ch 1.2-4, Bó Ch 5, 6.1
3 Number partitions, Ferrers diagrams and identities; Generating functions, Fibonacci sequence, and solving constant-coefficient linear recurrence relations Bó Ch 8, MN Ch 12.1-4
4 Generating functions: key examples, fundamental operations, products of generating functions Bó Ch 8, MN Ch 12.1-4
5 Generating functions for partitions, multivariate generating functions, the pentagonal theorem, composition of general functions Bó Ch 8, MN Ch 12.1-4
6 Exponential generating functions and their products and compositions
Asymptotic notation, exponential and factorial estimates
Bó Ch 8, MN Ch 12.1-4
MN Ch 3.4-5
7 Binomial estimates, rate of growth of the partition function
The Inclusion-Exclusion Principle, applications: Euler totient function, derangements
MN Ch 3.6, 12.7
MN Ch 3.7-8, Bó Ch 7.1-2
8 Posets: Sperner's theorem, Dilworth's theorem; Möbius inversion: general formula, inversion in the Boolean poset MN Ch 7.2, Bó Ch 16.1-2
9 The pigeonhole principle and applications: Chinese Remainder Theorem, Erdős-Szekeres theorem, Ramsey's theorem and upper and lower bounds on Ramsey numbers
10 Graph theory: basic definitions, notation, examples, Handshake lemma, connectedness, Eulerian graphs (statement) We Ch 1
11 Graph theory: proof of Euler's Theorem, Bipartite graphs (examples, basic theorems, characterization), Extremal problems (acyclicity, connectivity, Hamiltonicity, triangle-freeness) We Ch 1.2-3, 7.2
12 Equivalent characterisations of trees, spanning trees and Kruskal's algorithm, counting trees via the Prüfer code
Matchings and augmenting paths
MN 8.4, We Ch 2.1-2
We Ch 3.1
13 Characterization of maximum matchings, Hall's Theorem, Applications, vertex covers, König's Theorem, connectivity, examples, characterization of 2-connected graphs; colourings, chromatic number MN, We
14 Lower and upper bound on the chromatic number, their tightness, Mycielski's Construction; curves, planar drawings, planar graphs, plane graphs, Euler's formula, maximum number of edges in a planar graph, Kuratowski's Theorem (no proof), 5-colour theorem, 4-colour theorem (no proof) MN, We
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