1 What Is Combinatorics?
1.1 Example��Perfect Covers of Chessboards
1.2 Example��Magic Squares
1.3 Example��The Fou r-CoIor Problem
1.4 Example��The Problem of the 36 C)fficers
1.5 Example��Shortest-Route Problem
1.6 Example��Mutually Overlapping Circles
1.7 Example��The Game of Nim
1.8 Exercises

2 Permutations and Combinations
2.1 Four Basic Counting Principles
2.2 Permutations of Sets
2.3 Combinations(Subsets)of Sets
2.4 Permutations ofMUltisets
2.5 Cornblnations of Multisets
2.6 Finite Probability
2.7 Exercises

3 The Pigeonhole Principle
3.1 Pigeonhole Principle��Simple Form
3.2 Pigeon hole Principle��Strong Form
3.3 A Theorem of Ramsey
3.4 Exercises

4 Generating Permutations and Cornbinations
4.1 Generating Permutations
4.2 Inversions in Permutations
4.3 Generating Combinations
4.4 Generating r-Subsets
4.5 PortiaI Orders and Equivalence Relations
4.6 Exercises

5 The Binomiaf Coefficients
5.1 Pascals Triangle
5.2 The BinomiaI Theorem
5.3 Ueimodality of BinomiaI Coefficients
5.4 The Multinomial Theorem
5.5 Newtons Binomial Theorem
5.6 More on Pa rtially Ordered Sets
5.7 Exercises

6 The Inclusion-Exclusion P rinciple and Applications
6.1 The In Clusion-ExclusiOn Principle
6.2 Combinations with Repetition
6.3 Derangements+
6.4 Permutations with Forbidden Positions
6.5 Another Forbidden Position Problem
6.6 M6bius lnverslon
6.7 Exe rcises

7 Recurrence Relations and Generating Functions
7.1 Some Number Sequences
7.2 Gene rating Functions
7.3 Exponential Generating Functions
7.4 Solving Linear Homogeneous Recurrence Relations
7.5 Nonhomogeneous Recurrence Relations
7.6 A Geometry Example
7.7 Exercises

8 Special Counting Sequences
8.1 Catalan Numbers
8.2 Difference Sequences and Sti rling Numbers
8.3 Partition Numbers
8.4 A Geometric Problem
8.5 Lattice Paths and Sch rSder Numbers
8.6 Exercises Systems of Distinct ReDresentatives

9.1 GeneraI Problem Formulation
9.2 Existence of SDRs
9.3 Stable Marriages
9.4 Exercises

10 CombinatoriaI Designs
10.1 Modular Arithmetic
10.2 Block Designs
10.3 SteinerTriple Systems
10.4 Latin Squares
10.5 Exercises

11 fntroduction to Graph Theory
11.1 Basic Properties
11.2 Eulerian Trails
11.3 Hamilton Paths and Cycles
11.4 Bipartite Multigraphs
11.5 Trees
11.6 The Shannon Switching Game
11.7 More on Trees
11.8 Exercises

12 More on Graph Theory
12.1 Chromatic Number
12.2 Plane and Planar Graphs
12.3 A Five-Color Theorem
12.4 Independence Number and Clique Number
12.5 Matching Number
12.6 Connectivity
12.7 Exercises

13 Digraphs and Networks
13.1 Digraphs
13.2 Networks
13.3 Matchings in Bipartite Graphs Revisited
13.4 Exercises

14 Polya Counting
14.1 Permutation and Symmetry Groups
14.2 Bu rnsides Theorem
14.3 Polas Counting Formula
14.4 Exercises
Answers and Hints to Exercises