Abstract.
A theorem by Krein and Langer asserts existence of factorizations of special type for operator functions in a generalized Schur class, i. e., meromorphic operator functions defined on the unit disk and such that their Nevanlinna-Pick kernel has a fixed finite number of negative squares. A different view and proof of this theorem are presented, based on description of pole data of meromorphic operator functions in terms of pole pairs and pole triples. A criterion for existence, and a parametrization, of operator functions in a generalized Schur class with given pole triple is obtained.
Similar content being viewed by others
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Bolotnikov, V., Rodman, L. Krein-Langer Factorizations via Pole Triples. Integr. equ. oper. theory 47, 169–195 (2003). https://doi.org/10.1007/s00020-002-1158-z
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/s00020-002-1158-z