Showing the process of propagation and pruning, assuming τ = 15. All edges shown have an edge length of 10. Initially, we have the graph in (a), in which the edges (6,7) and (5,7) have no reference markers. The marker attached to edge (7,8) is propagated along incoming edges up to a distance of τ, resulting in the graph shown in (b). Note that the marker has been added to edges on both the top and bottom branch. Finally, in the pruning phase, each marker is checked for connectedness. On the top branch, the newly added marker is connected, while on the bottom branch, no adjacent marker connects, so the marker is pruned.