Figure 2.

Stability region and robust stability region in S complex domain. All the eigenvalues on the left-hand side of jw axis (i.e. σ = 0) ensure that the network is stable. All the eigenvalues on the left-hand side of axis σ = −σ₀ mean the network with stability margin (or robustness) σ₀ If the eigenvalues are all on the left-hand side of axis σ = −σ₁ it means the network is with robustness σ₁ A genetic network with larger robustness means it can tolerate larger intrinsic genetic variations and filter larger extrinsic disturbances.