Abstract
Let $\varphi$ be an elliptic automorphism of the open unit disc of order~$k$ and rotation parameter $w$, and let $C_{\varphi}$ be the composition operator on the Hardy space $H^2$ induced by $\varphi$. Then there are orthogonal projections $P_{s}$, $s=0, 1,\ldots, k-1$ with identical norm such that $C_{\varphi}=\sum_{s=0}^{k-1} w^s P_{s}$.
Citation
M.T. Heydari. "Decomposition for a composition operator." Rocky Mountain J. Math. 44 (2) 531 - 538, 2014. https://doi.org/10.1216/RMJ-2014-44-2-531
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