Graphs and Applications

1 Introduction.- 1.1 Graphs, Digraphs and Networks.- 1.2 Classifying Problems.- 1.3 Seeking Solutions.- 2 Graphs.- 2.1 Graphs and Subgraphs.- 2.2 Vertex Degrees.- 2.3 Paths and Cycles.- 2.4 Regular and Bipartite Graphs.- 2.5 Case Studies.- Exercises 2.- 3 Eulerian and Hamiltonian Graphs.- 3.1 Exploring and Travelling.- 3.2 Eulerian Graphs.- 3.3 Hamiltonian Graphs.- 3.4 Case Studies.- Exercises 3.- 4 Digraphs.- 4.1 Digraphs and Subdigraphs.- 4.2 Vertex Degrees.- 4.3 Paths and Cycles.- 4.4 Eulerian and Hamiltonian Digraphs.- 4.5 Case Studies.- Exercises 4.- 5 Matrix Representations.- 5.1 Adjacency Matrices.- 5.2 Walks in Graphs and Digraphs.- 5.3 Incidence Matrices.- 5.4 Case Studies.- Exercises 5.- 6 Tree Structures.- 6.1 Mathematical Properties of Trees.- 6.2 Spanning Trees.- 6.3 Rooted Trees.- 6.4 Case Study.- Exercises 6.- 7 Counting Trees.- 7.1 Counting Labelled Trees.- 7.2 Counting Binary Trees.- 7.3 Counting Chemical Trees.- Exercises 7.- 8 Greedy Algorithms.- 8.1 Minimum Connector Problem.- 8.2 Travelling Salesman Problem.- Exercises 8.- 9 Path Algorithms.- 9.1 Fleury’s Algorithm.- 9.2 Shortest Path Algorithm.- 9.3 Case Study.- Exercises 9.- 10 Paths and Connectivity.- 10.1 Connected Graphs and Digraphs.- 10.2 Menger’s Theorem for Graphs.- 10.3 Some Analogues of Menger’s Theorem.- 10.4 Case Study.- Exercises 10.- 11 Planarity.- 11.1 Planar Graphs.- 11.2 Euler’s Formula.- 11.3 Cycle Method for Planarity Testing.- 11.4 Kuratowski’s Theorem.- 11.5 Duality.- 11.6 Convex Polyhedra.- Exercises 11.- 12 Vertex Colourings and Decompositions.- 12.1 Vertex Colourings.- 12.2 Algorithm for Vertex Colouring.- 12.3 Vertex Decompositions.- Exercises 12.- 13 Edge Colourings and Decompositions.- 13.1 Edge Colourings.- 13.2 Algorithm for Edge Colouring.- 13.3 EdgeDecompositions.- Exercises 13.- 14 Conclusion.- 14.1 Classification of Problems.- 14.2 Efficiency of Algorithms.- 14.3 Another Classification of Problems.- Suggestions for Further Reading.- Appendix: Methods of Proof.- Computing Notes.- Solutions to Computer Activities.- Solutions to Problems in the Text.