Appendix A. Introduction to graphs
This appendix covers
- What is a graph and the fundamental mathematical concepts behind graph theory
- How graphs serve as models for representing real-world networks across domains
- Standard methods for representing graphs using adjacency lists and matrices
Even though graphs are simple data structures, it is important to understand how to represent them and to know the main concepts around it. This appendix introduces the key elements of the graph world. If you already know such concepts, or you read Alessandro’s previous book [1] from which the following sections have been extracted, you can skip this appendix.
A.1 What is a graph?
The graph is a simple and quite old mathematical concept. It is a data structure consisting of a set of vertices (or nodes/points) and edges (or relationships/lines) that can be used to model relationships among a collection of objects.