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JOURNALS // Zapiski Nauchnykh Seminarov POMI // Archive

Zap. Nauchn. Sem. POMI, 2019 Volume 480, Pages 148–161 (Mi znsl6768)

This article is cited in 1 paper

Nearly invariant subspaces and rational interpolation

V. V. Kapustin

St. Petersburg Department of Steklov Mathematical Institute of Russian Academy of Sciences

Abstract: Given an inner function $\theta$ in the upper half-plane, consider the subspace $H^2\ominus\theta H^2$ of the Hardy space $H^2$. For a finite collection $\Lambda$ of points on the complex plane, the subspace of functions from $K_\theta$ that vanish on $\Lambda$ can be represented in the form $g\cdot K_\omega$, where $\omega$ is an inner function and $g$ is an isometric multiplier on $K_\omega$. We obtain a description of the functions $\omega$ and $g$ in terms of $\theta$ and $\Lambda$.

Key words and phrases: Hardy class, model spaces, Schur algorithm.

UDC: 517.58

Received: 26.08.2019



© Steklov Math. Inst. of RAS, 2024