Abstract
In this paper, we investigate conditionally completely positive definite kernels in the setting of Hilbert \(C^*\)-modules. At first, we present a correspondence between conditionally completely positive definite kernels and completely positive definite kernels. Utilizing this relation, we give the Kolmogorov decomposition for a certain conditionally completely positive definite kernel. We present a characterization of conditionally completely positive definite kernels majorized by a kernel under some mild conditions. Finally, as an application of this decomposition, we find a sufficient condition for the existence of an extreme point of a convex set consisting of some special kernels.
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Ghaemi, M., Moslehian, M.S. & Xu, Q. Kolmogorov decomposition of conditionally completely positive definite kernels. Positivity 25, 515–530 (2021). https://doi.org/10.1007/s11117-020-00777-3
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DOI: https://doi.org/10.1007/s11117-020-00777-3
Keywords
- Kolmogorov decomposition
- Completely positive definite kernel
- Conditionally completely positive definite kernel
- Extreme point