Robustness is the property of being strong and healthy in constitution. When we transpose it to a system, it refers to the ability of tolerating perturbations that might affect the system’s functional body . In the same line Robustness can be defined as "the ability of a system to resist change without adapting its initial stable configuration". When perturbations are small in magnitude we speak about "Robustness in the small", always keeping in mind that the ”small” magnitude hypothesis is hard to be verified since small or large depends on the specific problem. Conversely, we say that we address a "Robustness in the large problem" when no assumptions are made about the magnitude of perturbations, which can either be small or large. It has been discussed that robustness has two dimensions: resistance and avoidance.