Figure 1. Overview of networks. Each network consists of two pathways S1 → X1 (Left) and S2 → X2 (Right).

The pathways may interact via regulatory interactions and a shared component. Solid arrows are either activating or repressive, while dashed arrows can be activating, repressive or absent. a) 6 node topology. b) 6 different possible incoherent feed-forward loops marked by colored arrows (magenta activating, light blue repressing) c) 5 node topology. d) example of an incoherent and coherent feed-forward loop for a 5 node topology (+ activating, − repressing).