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This article is cited in 4 scientific papers (total in 4 papers)
Compact Operators and Uniform Structures in Hilbert $C^*$-Modules
E. V. Troitskiiab, D. V. Fufaevab a Moscow Center for Fundamental and Applied Mathematics, Moscow, Russia
b Department of Mechanics and Mathematics, Lomonosov Moscow State University, Moscow, Russia
Abstract:
Quite recently a criterion for the $\mathcal{A}$-compactness of an ajointable operator $F\colon\M\to\mathcal{N}$ between Hilbert $C^*$-modules, where $\mathcal{N}$ is countably generated, was obtained. Namely, a uniform structure (a system of pseudometrics) in $\mathcal{N}$ was discovered such that $F$ is $\mathcal{A}$-compact if and only if $F(B)$ is totally bounded, where $B\subset\M$ is the unit ball.
We prove that (1) for a general $\mathcal{N}$, $\mathcal{A}$-compactness implies total boundedness, (2) for $\mathcal{N}$ with $\mathcal{N}\oplus K\cong L$, where $L$ is an uncountably generated $\ell_2$-type module, total boundedness implies compactness, and (3) for $\mathcal{N}$ close to be countably generated, it suffices to use only pseudometrics of “frame-like origin” to obtain a criterion for $\mathcal{A}$-compactness.
Keywords:
Hilbert $C^*$-Module, uniform structure, totally bounded set, compact operator, $\mathcal{A}$-compact operator, frame.
Received: 15.06.2020 Revised: 15.07.2020 Accepted: 21.07.2020
Citation:
E. V. Troitskii, D. V. Fufaev, “Compact Operators and Uniform Structures in Hilbert $C^*$-Modules”, Funktsional. Anal. i Prilozhen., 54:4 (2020), 74–84; Funct. Anal. Appl., 54:4 (2020), 287–294
Linking options:
https://www.mathnet.ru/eng/faa3809https://doi.org/10.4213/faa3809 https://www.mathnet.ru/eng/faa/v54/i4/p74
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