Higher order ${\mathcal{S}}^p$-differentiability: The unitary case

Arup Chattopadhyay, Clément Coine, Saikat Giri +1

Consider the set of unitary operators on a complex separable Hilbert space $\hilh$, denoted as $\mathcal{U}(\hilh)$. Consider $1<p<\infty$. We establish that a function $f$ defined…