Evolution window

It was observed in evolution strategies that significant progress toward the fitness/objective function's optimum, generally, only can happen in a narrow band of the mutation step size σ. That narrow band is called evolution window.

There are three well-known methods to adapt the mutation step size σ in evolution strategies:


 * (1/5-th) success rule
 * self-adaptation
 * cumulative step size adaptation

On simple functions all of them have been empirically shown to keep the step size within the evolution window.