Table of Contents
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Contents
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The Beginning
Modeling problems with graphs
Coloring Switzerland
The seven dwarfs
The Towers of Hanoi
A tiling puzzle
Taking photos efficiently
Match the cars and drivers
Practice problems
Isomorphisms and subgraphs
Circulant graphs
Are these the same?
The isomorphism game
Graph invariants
Subgraphs and some common graphs
Practice problems
Walks, paths, and cycles
Walks and paths
Connected graphs
Equivalence relations
Closed walks and cycles
Lengths of walks
Practice problems
The degree of a vertex
Hypercube graphs
The handshake lemma
Degrees and connectedness
Degrees and cycles
Average degree
Practice problems
Vertex Degrees
Regular graphs
Degree sequences
Regular graphs
How many regular graphs are there?
The Petersen graph
The degree/diameter problem
Practice problems
Graphic sequences
An unusual party
A graphic sequence algorithm
Two examples
The Havel–Hakimi theorem
More on degree sequences
Practice problems
Multigraphs and digraphs
Multigraphs
Degrees in multigraphs
Directed graphs
Directed walks, paths, and cycles
Practice problems
Euler tours
Don't lift your pencil!
First steps
Cycle decompositions
Gluing cycles together
Variations on Euler tours
Practice problems
Trees
Trees and spanning trees
Spanning trees
Bridges
Properties of trees
Minimum-cost spanning trees
Practice problems
Properties of trees
A square garden
Counting edges in trees
From trees to forests
Leaves in trees
Induction on trees
Practice problems
Cayley's formula
How to count graphs
Trees and deletion sequences
Prüfer codes
Working with Prüfer codes
Unlabeled trees
Practice problems
Directed acyclic graphs
Directed acyclic graphs
Topological orders
Strongly connected
Condensations
Practice problems
Matchings
Bipartite graphs
Two chess puzzles
Bipartite graphs
Odd cycles
Matching problems
Maximum and maximal
Vertex covers
Practice problems
Kőnig's theorem
Kőnig's theorem
Augmenting paths
The augmenting path algorithm
Analyzing the algorithm
Using the algorithm
Practice problems
Hall's theorem
Hall's theorem
Regular bipartite graphs
A three-card magic trick
Generalized tic-tac-toe
Incomparable sets
Practice problems
Matchings in general graphs
Tutte sets
Saturated graphs
Proof of Tutte's theorem
1-factorizations
Increasing walks
Practice problems
Hard Problems
Hamilton cycles
Knight's tours
Two examples
Tough graphs
Sufficient conditions
Practice problems
Cliques and independent sets
Two problems about queens
Redundancies and relationships
Greedy algorithms
An indecisive algorithm
Ramsey numbers
Lower bounds
Practice problems
Graph coloring
Graph coloring and Sudoku
Greedy coloring
Two lower bounds
Coloring interval graphs
Mycielski graphs
Practice problems
Line graphs
Line graphs
Euler tours and Hamilton cycles
De Bruijn sequences
Edge coloring
Vizing's theorem
Practice problems
Planar Graphs
Planar graphs
Three utilities
Planar graphs
Faces
Euler's formula
Barycentric subdivisions
Technical details
Practice problems
Planarity testing
Counting edges in planar graphs
Triangulations
Girth and planarity
Subdivisions
Graph minors
Overlap graphs
Practice problems
Polyhedra
The Platonic solids
Classifying the Platonic solids
Dual graphs
Archimedean solids
Practice problems
Coloring maps
Coloring maps
The four color theorem
Greedy coloring
Five colors
Hamilton cycles
Coloring empires
Practice problems
Connectivity
Cut vertices
Counting paths
Cut vertices
2-connected graphs
Ear decompositions
Induction on ears
Finding common cycles
Practice problems
Connectivity
Vertex and edge cuts
Some examples
Local connectivity
Duality
Practice problems
Menger's theorem
Menger's theorem
Kőnig-type graphs
Reducing all other cases
Extensions
Cuts and long cycles
Practice problems
Maximum flows
Shipping oranges
Maximum flow problems
Network cuts
The Ford–Fulkerson algorithm
Counting iterations
Consequences
Practice problems
Appendix
Review of proof-writing
Conditional statements
Quantifiers
Unpacking definitions
Optimization problems
Algorithms
The extremal principle
Practice problems
Proof by induction
The logic of induction
Induction on graphs
Inductive definitions
Recursive constructions
Practice problems
Bibliography