Essentially normal composition operators on H-2

摘要

We prove a simple criterion for essential normality of composition operators on the Hardy space induced by maps in a reasonably large class S of analytic self-maps of the unit disk. By combining this criterion with boundary Caratheodory-Fejer interpolation theory, we exhibit a parametrization for all rational self-maps of the unit disk which induce essentially normal composition operators. (C) 2018 Elsevier Inc. All rights reserved.