“…Using the same techniques as the previous authors, Qin et al have studied the controllability and optimal control of fractional dynamical systems of order 1 < q < 2 in Banach spaces [24]. Yan and Jia used stochastic analysis theory and fixed-point theorems with the strongly continuous α-order cosine family to study an optimal control problem for a class of stochastic fractional equations of order α ∈ (1,2] in Hilbert spaces [25]. In 2021, Zhou and He obtained, via the contraction principle and Shauder's fixed-point theorem, a set of sufficient conditions for the exact controllability of a class of fractional systems [26].…”