On Continuously Differentiable Vector-Valued Functions of Non-Integer Order

Abstract: The function spaces of continuously differentiable functions are extensively studied and appear in various mathematical settings. In this context, we investigate the spaces of continuously fractional differentiable functions of order $\alpha>0$, considering both the Riemann-Liouville and Caputo fractional derivatives. We explore several fundamental properties of these spaces and, inspired by a result of Hardy and Littlewood, we compare them with the space of H\"older continuous functions. Our main objective is to establish a rigorous theoretical framework to support the study and further advancement of this subject.