Figure 4
From: Public communication can facilitate low-risk coordination under surveillance
Visited and reached nodes in the sample of the Facebook social graph. We give an example of how our simulations treat differently the visited and reached nodes, as defined by the Breadth-First-Search (BFS) crawling on the Facebook social graph28,29. In the example, the visited nodes, that is, the nodes completely explored by the BFS are \(v_{1}\), \(v_{2}\), \(v_{3}\), and \(v_{4}\) (green squares), while the reached nodes, that is, the nodes only reached by the BFS are \(r_{1}\), \(r_{2}\), and \(r_{3}\) (gray circles). All edges are unweighted and denote the fact that the two endpoints of an edge are friends in the Facebook social graph. However, while the edges incident to visited nodes (solid lines) are included in the network used in our simulations, the edges between two reached nodes (dashed lines) are not considered (even if the corresponding two Facebook users are friends). On the right, we show the adjacency lists that would be used in our simulations with regards to the aforementioned example: As it can be seen, there is no adjacency list for the reached nodes, since the neighborhood of these nodes has not been fully explored.
