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arXiv · 2607.27799

When do Kernels Admit Characteristic Functions?

Caixing Gu·Shuaibing Luo·Georgios Tsikalas·Min Zhou
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Abstract

A general framework for deriving characteristic functions for reproducing kernels that do not necessarily possess the complete Pick property was recently established by Bhattacharyya and Jindal. We show that, in this setting, the existence of a characteristic function is equivalent to a Beurling-type invariant subspace condition. Combined with recent results characterizing kernels satisfying this condition, our theorem implies that the existence of a characteristic function is equivalent to a concrete Agler-type decomposition of the underlying kernels.

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Caixing Gu, Shuaibing Luo, Georgios Tsikalas, Min Zhou. 2026-07-30. When do Kernels Admit Characteristic Functions?. https://arxiv.org/abs/2607.27799

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