Superposition operators, Hardy spaces, and Dirichlet type spaces

Petros Galanopoulos, Daniel Girela, María Auxiliadora Márquez

For $0<p<\infty$ and $\alpha >-1$ the space of Dirichlet type ${\mathcal{D}}_{\alpha }^p$ consists of those functions $f$ which are analytic in the unit disc $\mathbb{D}$ and satisfy $\int_{\mathbb…