4.1 Graphs and Graph Structures4.1.1 A Glimpse on Graph Theory4.1.2 Graph Traversal and Graph Problems4.2 Graph Data Structures4.2.1 Edge List4.2.2 Adjacency Matrix4.2.3 Incidence Matrix4.2.4 Adjacency List4.2.5 Incidence List4.3 The Property Graph Model4.4 Storing Property Graphs in Relational Tables4.5 Advanced Graph Models4.6 Implementations and Systems4.6.1 Apache TinkerPop4.6.2 Neo4J4.6.3 HyperGraphDB4.7 Bibliographic Notes