Study Guide 
Tucker: Applied Combinatorics 
§App.4 - The Pigeonhole Principle
Dr. Lee Eimers

Introduction: In this section you become acquainted with one of the most useful principles for proofs in mathematics. In its simplest form it is very straightforward, but its application can involve great subtilty.


Concepts and Vocabulary: The following boldfaced (or italic) terms and phrases introduced in this section. (These are just 3 names for the same thing.)
Dirichlet's Box Principle
Dirichlet drawer principle
Pigeonhole principle

Points of Interest:

1.  Study the examples closely. They will give you some idea of the variety of situations that the pigeonhole principle applies to.

2.  Pay close attention to the examples studied in class. We will do some rather sophisticated reasoning to be able to apply this principle.


Homework Assignment:
Go to Pigeonhole Principle.
Study the examples. Try some examples from the list of 32 at the end of the page.

From Tucker, Appendix A.4: Do these to see how well you understand: #3, 5, 6, 8, 11
Enrichment problems: Anything after #8 not already covered in class.

Web Sites Related to Appendix 4
The Pigeon Hole Principle
    Good discussion of the P.H.P. and many good examples.
The Pigeon Hole Principle
    A series of web pages with theory and problems
    involving the P.H.P. by Ludmil Katzarkov, UC Irvine.
The Pigeon Hole Principle
   Very good collection of problems
The Pigeon Hole Principle
   Has an interesting birthday problem.
The Pigeon Hole Principle
  Application problems: some good examples. (Don't peek at solutions  until you try them.)
Pigeon-hole principle originator
  Picture and brief bio of DIRICHLET-LEJEUNE, Johann Peter Gustav

Thought for the Day
Wisdom is the principal thing;
Therefore get wisdom:
And with all thy getting get understanding.
Prov. 4:7