Interaction graph and logical model of the EGF/NRG1 network example. Both models were set up and visualized in Promot . (A) Interaction graph of the EGF/NRG1 example model. Black arrows indicate positive (activating) edges, red blunt-ended lines negative (inhibiting) edges. (B) Hypergraph representation of a Boolean model with underlying interaction graph given in (A). Blue circles denote AND operations, that is, a hyperedge with n inputs is represented as n arrows pointing into a blue circle and one arrow pointing out of it. Red blunt-ended lines indicate that the respective input value is negated. Several arrows pointing into one node are OR connected.