Abstract
In this study, we partially answer a question left open in Rudin’s book “Function Theory in Polydisks” on the structure of invariant subspaces of the Hardy space H 2(U n) on the polydisk U n. We completely describe all invariant subspaces generated by a single function in the polydisk. Then, using our results, we prove the unitary equivalence of this type of invariant subspace and a characterization of outer functions in H 2(U n).
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References
O. P. Agrawal, D. N. Clark, and R. G. Douglas, “Invariant subspaces in the polydisk,” Pacific J. Math. 121 (1), 1–11 (1986).
A. Beurling, “On two problems concerning linear transformations in Hilbert space,” Acta Math 81, 239–255 (1948).
C. A. Jacewicz, “A nonprincipal invariant subspace of the Hardy space on the torus,” Proc. Amer. Math. Soc. 31, 127–129 (1972).
V. Mandrekar, “The validity of Beurling theorems in polydisks,” Proc. Amer. Math. Soc. 103, 145–148 (1988).
H. Radjavi and P. Rosenthal, Invariant Subspaces, in Ergebnisse der Mathematik und ihrer Grenzgebiete (Springer-Verlag, New York–Heidelberg, 1973), Band 77.
W. Rudin, Function Theory in Polydisks (W. A. Benjamin, Inc., New York–Amsterdam 1969).
N. M. Sadikov, “Invariant subspaces in the Hardy space on a polydisk that are generated by inner functions,” Akad. Nauk Azerbaidzhan. SSR Dokl. 39 (3), 8–11 (1983) [in Russian].
J. Sarkar, A. Sasane, and B. D. Wick, “Doubly commuting submodules of the Hardy module over polydisks,” Studia Math. 217 (2), 179–192 (2013).
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Koca, B.B., Sadik, N. Invariant subspaces generated by a single function in the Polydisk. Math Notes 102, 193–197 (2017). https://doi.org/10.1134/S0001434617070215
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DOI: https://doi.org/10.1134/S0001434617070215