Abstract
We give an elementary proof of Sarason’s solvability criterion for the Nevanlinna–Pick problem with boundary interpolation nodes and boundary target values. We also give a concrete parametrization of all solutions of such a problem. The proofs are based on a reduction method due to Julia and Nevanlinna. Reduction of functions corresponds to Schur complementation of the corresponding Pick matrices.
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J. Agler is partially supported by National Science Foundation Grant DMS 0801259 and N. J. Young is supported by EPSRC Grant EP/G000018/1.
An erratum to this article can be found at http://dx.doi.org/10.1007/s00209-010-0839-6
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Agler, J., Young, N.J. Boundary Nevanlinna–Pick interpolation via reduction and augmentation. Math. Z. 268, 791–817 (2011). https://doi.org/10.1007/s00209-010-0696-3
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DOI: https://doi.org/10.1007/s00209-010-0696-3