Bipartite subgraph, explained in text before the figure. This figure shows three vertices (ID values 99 and 333 on the left, and ID 128 on the right). The vertices on the left have the isLeft value of true. The vertex on the right has the isLeft value of false. ID 128 is connected to ID 99 with an edge that has a cost value of 8.51, and ID 333 is connected to ID 128 with an edge that has a cost value of 51.09.