Model spaces invariant under composition operators

Abstract Given a holomorphic self-map $\varphi $ of $\mathbb {D}$ (the open unit disc in {C}$ ), the composition operator $C_{\varphi } f = \circ \varphi , $f \in H^2(\mathbb {\mathbb {D}})$ defines bounded linear on Hardy space $H^2(\mathbb . The model spaces are backward shift-invariant closed subspaces which canonically associated with inner functions. In this paper, we study that invariant under operators. Emphasis is put finite-dimensional spaces, affine transformations, and fractional transformations.