Strong nonuniform behaviour: A Datko type characterization

We obtain a Datko-type characterization of several classes of a strong nonuniform exponential behaviour. We consider separately the case of exponential contractions, expansions and dichotomies. In addition, we consider both discrete and continuous time. As a nontrivial application of our work, we study the robustness property of strong nonuniform exponential contractions, expansions and dichotomies.