Discrete mathematics : elementary and beyond
L. Lovász, J. Pelikán, K. Vesztergombi
18250152
TABLE DES MATIÈRES
Preface vii
1 Let’s Count!
1
1.1 A Party
1
1.2 Sets and the Like
4
1.3 The Number of Subsets
9
1.4 The Approximate Number of Subsets
14
1.5 Sequences
15
1.6 Permutations
17
1.7 The Number of Ordered Subsets
19
1.8 The Number of Subsets of a Given Size
20
2 Combinatorial Tools
25
2.1 Induction
25
2.2 Comparing and Estimating Numbers
30
2.3 Inclusion-Exclusion
32
2.4 Pigeonholes
34
2.5 The Twin Paradox and the Good Old Logarithm
37
3 Binomial Coefficients and Pascal’s Triangle
43
3.1 The Binomial Theorem
43
3.2 Distributing Presents
45
3.3 Anagrams
46
3.4 Distributing Money
48
3.5 Pascal’s Triangle
49
3.6 Identities in Pascal’s Triangle
50
3.7 A Bird’s-Eye View of Pascal’s Triangle
54
3.8 An Eagle’s-Eye View: Fine Details
57
4 Fibonacci Numbers
65
4.1 Fibonacci’s Exercise
65
4.2 Lots of Identities
68
4.3 A Formula for the Fibonacci Numbers
71
5 Combinatorial Probability
77
5.1 Events and Probabilities
77
5.2 Independent Repetition of an Experiment
79
5.3 The Law of Large Numbers
80
5.4 The Law of Small Numbers and the Law of Very
Large Numbers 83
6 Integers, Divisors, and Primes
87
6.1 Divisibility of Integers
87
6.2 Primes and Their History
88
6.3 Factorization into Primes
90
6.4 On the Set of Primes
93
6.5 Fermat’s « Little » Theorem
97
6.6 The Euclidean Algorithm
99
6.7 Congruences
105
6.8 Strange Numbers
107
6.9 Number Theory and Combinatorics
114
6.10 How to Test Whether a Number is a Prime?
117
7 Graphs 125
7.1 Even and Odd Degrees
125
7.2 Paths, Cycles, and Connectivity
130
7.3 Eulerian Walks and Hamiltonian Cycles
135
8 Trees 141
8.1 How to Define Trees
141
8.2 How to Grow Trees
143
8.3 How to Count Trees?
146
8.4 How to Store Trees
148
8.5 The Number of Unlabeled Trees
153
9 Finding the Optimum
157
9.1 Finding the Best Tree
157
9.2 The Traveling Salesman Problem
161
10 Matchings in Graphs
165
10.1 A Dancing Problem
165
10.2 Another matching problem
167
10.3 The Main Theorem
169
10.4 How to Find a Perfect Matching
171
11 Combinatorics in Geometry
179
11.1 Intersections of Diagonals
179
11.2 Counting regions
181
11.3 Convex Polygons
184
12 Euler’s Formula
189
12.1 A Planet Under Attack
189
12.2 Planar Graphs
192
12.3 Euler’s Formula for Polyhedra
194
13 Coloring Maps and Graphs
197
13.1 Coloring Regions with Two Colors
197
13.2 Coloring Graphs with Two Colors
199
13.3 Coloring graphs with many colors
202
13.4 Map Coloring and the Four Color Theorem
204
14 Finite Geometries, Codes, Latin Squares, and Other Pretty Creatures
211
14.1 Small Exotic Worlds
211
14.2 Finite Affine and Projective Planes
217
14.3 Block Designs
220
14.4 Steiner Systems
224
14.5 Latin Squares
229
14.6 Codes
232
15 A Glimpse of Complexity and Cryptography
239
15.1 A Connecticut Class in King Arthur’s
Court 239
15.2 Classical Cryptography
242
15.3 How to Save the Last Move in Chess
244
15.4 How to Verify a Password—Without Learning
it 246
15.5 How to Find These Primes
246
15.6 Public Key Cryptography
247
16 Answers to Exercises
251
5 février 2005