Fig. 1

(a) The asynchronous state-transition graph of the Boolean network in Example 1. Each state specifies the values of the network variables in the lexicographic order. The highlighted states show an oscillating attractor of the network. (b) The regulatory graph and update functions of the Boolean network in Example 1. Green and red arrows represent activating and inhibiting regulations, respectively. A solid arrow implies that the regulation is essential in the corresponding update function