Nets where at least two vertices have the same position are called unstable and, similarly to Systre, are generally not handled by our implementation. This is usually not problematic since their probability of occurrence is low . Our implementation can however handle unstable nets where each collision site comprises at most four vertices if there is no edge between two different collision sites and no collision site is bonded to two representatives of the same vertex. This accounts for roughly half of the encountered unstable nets in the databases we explored. We will not detail the case of these unstable nets here but focus on stable ones. We can thus assume that no two vertices have the same position.