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Algebra i Analiz, 2021 Volume 33, Issue 5, Pages 153–175 (Mi aa1780)

Research Papers

Limit behavior of Weyl coefficients

R. Pruckner, H. Woracek

Institute for Analysis and Scientific Computing, Vienna University of Technology Wiedner Hauptstrasse 8-10/101, 1040 Wien, Austria

Abstract: The sets of radial or nontangential limit points towards $i\infty$ of a Nevanlinna function $q$ are studied. Given a nonempty, closed, and connected subset $\mathcal{L}$ of $\overline{\mathbb C_+}$, a Hamiltonian $H$ is constructed explicitly such that the radial and outer angular cluster sets towards $i\infty$ of the Weyl coefficient $q_H$ are both equal to $\mathcal{L}$. The method is based on a study of the continuous group action of rescaling operators on the set of all Hamiltonians.

Keywords: Weyl coefficient, canonical system, cluster set, Nevanlinna function.

Received: 11.06.2019

Language: English


 English version:
St. Petersburg Mathematical Journal, 2022, 33:5, 849–865


© Steklov Math. Inst. of RAS, 2026