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Article
A spectral radius type formula for approximation numbers of composition operators
(Elsevier, 2014-12-15)
For approximation numbers an(Cφ) of composition operators Cφ on weighted analytic Hilbert spaces, including the Hardy, Bergman and Dirichlet cases, with symbol φ of uniform norm <1, we prove that limn→∞[an(Cφ)]1/n=e−1 ...
Article
Some new properties of composition operators associated with lens maps
(Springer, 2013-05)
We give examples of results on composition operators connected with lens maps. The first two concern the approximation numbers of those operators acting on the usual Hardy space H2. The last ones are connected with ...
Article
Approximation numbers of composition operators on Hp
(De Gruyter Open, 2015-01)
We give estimates for the approximation numbers of composition operators on the Hp spaces, 1 ≤ p < ∞.
Article
Two results on composition operators on the Dirichlet space
(Elsevier, 2015-06-15)
We show that the decay of approximation numbers of compact composition operators on the Dirichlet space D can be as slow as we wish. We also prove the optimality of a result of O. El-Fallah, K. Kellay, M. Shabankhah ...
Article
Approximation numbers of composition operators on the Dirichlet space
(Springer, 2015-04)
We study the decay of approximation numbers of compact composition operators on the Dirichlet space. We give upper and lower bounds for these numbers. In particular, we improve on a result of O. El-Fallah, K. Kellay, M. ...