On approximation numbers of composition operators

We show that the approximation numbers of a compact composition operator on the weighted Bergman spaces Bα of the unit disk can tend to 0 arbitrarily slowly, but that they never tend quickly to 0: they grow at least exponentially, and this speed of convergence is only obtained for symbols which do n...

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Detalles Bibliográficos
Autores: Li, Daniel, Queffélec, Hervé, Rodríguez Piazza, Luis
Tipo de recurso: artículo
Estado:Versión enviada para evaluación y publicación
Fecha de publicación:2012
País:España
Institución:Universidad de Sevilla (US)
Repositorio:idUS. Depósito de Investigación de la Universidad de Sevilla
OAI Identifier:oai:idus.us.es:11441/46366
Acceso en línea:http://hdl.handle.net/11441/46366
https://doi.org/10.1016/j.jat.2011.12.003
Access Level:acceso abierto
Palabra clave:Approximation number
Bergman space
Carleson measure
Composition operator
Hardy space
Interpolation sequence
Reproducing kernel
Weighted Bergman space
Weighted shift
Descripción
Sumario:We show that the approximation numbers of a compact composition operator on the weighted Bergman spaces Bα of the unit disk can tend to 0 arbitrarily slowly, but that they never tend quickly to 0: they grow at least exponentially, and this speed of convergence is only obtained for symbols which do not approach the unit circle. We also give an upper bounds and explicit an example.