Schematic representation of ASTDWand ASTDL. The four bold-line blocks of z19, z20, z10 and z11 on the left side show the corresponding temporal subnets that are the minimal element sets at respective time points. Dashed-line block shows the state transitions of "z19→z20→z10↔z11" in the ASTD and corresponding detailed regulation variations of HFPNe elements. For example, in the structural transformation from z19 to z20, two inhibitory arcs a(p13, t10) and a(p13, t14) are enabled due to the increase in the concentration of PER/TIM, resulting in the deletion of four arcs a(p5, t10), a(p5, t14), a'(t10, p6) and a'(t14, p8). Note that the transformation from z11 to z10 is omitted.