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Outer factorizations in one and several variables

Michael A. Dritschel·Hugo J. Woerdeman
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Abstract

A multivariate version of Rosenblum's Fejer-Riesz theorem on outer factorization of trigonometric polynomials with operator coefficients is considered. Due to a simplification of the proof of the single variable case, new necessary and sufficient conditions for the multivariable outer factorization problem are formulated and proved.

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Michael A. Dritschel, Hugo J. Woerdeman. 2004-03-04. Outer factorizations in one and several variables. https://arxiv.org/abs/math/0403099

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