EN
We consider Besov and Lizorkin-Triebel algebras, that is, the real-valued function spaces $B_{p,q}^{s}(ℝⁿ) ∩ L_{∞|(ℝ)$ and ${F_{p,q}^{s}(ℝⁿ)} ∩ L_{∞}(ℝ)$ for all s > 0. To each function f: ℝ → ℝ one can associate the composition operator $T_{f}$ which takes a real-valued function g to the composite function f∘g. We give necessary conditions and sufficient conditions on f for the continuity, local Lipschitz continuity, and differentiability of any order of $T_{f}$ as a map acting in Besov and Lizorkin-Triebel algebras. In some cases, such as for n = 1, such conditions turn out to be necessary and sufficient.