Factorization and approximation problems for matrix functions

Peller, V.

doi:10.1090/S0894-0347-98-00274-4

Factorization and approximation problems for matrix functions
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by V. V. Peller

J. Amer. Math. Soc. 11 (1998), 751-770

DOI: https://doi.org/10.1090/S0894-0347-98-00274-4

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Abstract:

We study maximizing vectors of Hankel operators with matrix-valued symbols. This study leads to a solution of the so-called recovery problem for unitary-valued functions and to a new approach to Wiener–Hopf factorizations for functions in a function space $X$ satisfying natural conditions. Finally, we improve earlier results of Peller and Young on hereditary properties of the operator of superoptimal approximation by analytic matrix functions.

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