Function spaces and embeddings

Function spaces of Besov or Triebel-Lizorkin type, Bsp,q and F s p,q, respectively,

will serve as outstanding examples in the sequel. Thus we recall briefly the basic ingredients needed for their introduction. In addition, we collect wellknown characterisations and embedding results. Note that all spaces are defined on Rn unless otherwise stated; so we shall omit the “Rn” in the sequel.