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Weighted composition operators in weighted Banach spaces of analytic functions. (English) Zbl 0990.47018

Let \(H({\mathbf D})\) be the set of analytic functions in the unit disk \(\mathbf D\). A weight is a positive nonincreasing on \(|z|\) continuous function \(\nu (z)=\nu (|z|)\). The authors characterize the boundedness and compactness of weighted composition operators \(C_{\varphi, \psi}\) given by \(C_{\varphi, \psi}(f)=\psi(f\circ \varphi)\), where \(\varphi, \psi \in H({\mathbf D})\) and \(\varphi ({\mathbf D}) \subseteq {\mathbf D}\), acting between the spaces \(H^{\infty}_{\nu}= \{f \in H({\mathbf D}): \sup_{z \in {\mathbf D}} \nu(z) |f(z)|< \infty\}\) and \(H^0_{\nu}= \{f \in H({\mathbf D}): \lim_{|z|\rightarrow 1} \nu(z) |f(z)|=0\}\). They estimate the essential norm of the operator \(C_{\varphi, \psi}\) and compute it for the spaces \(H^0_{\nu}\) which are isomorphic to \(c_0\). It shown as well that being non compact a weighted composition operator is an isomorphism on a subspace isomorphic to \(c_0\) or \(\ell_{\infty}\). In the final section the authors study boundedness and compactness properties of composition operators acting between Bloch type spaces and little Bloch type spaces.

MSC:

47B33 Linear composition operators
30D45 Normal functions of one complex variable, normal families
46E15 Banach spaces of continuous, differentiable or analytic functions
47B38 Linear operators on function spaces (general)
47B07 Linear operators defined by compactness properties