On Hardy-Littlewood-P�lya and Taikov type inequalities for multiple operators in Hilbert spaces

V Babenko, Y Babenko, N Kriachko…�- Analysis Mathematica, 2021 - Springer
V Babenko, Y Babenko, N Kriachko, D Skorokhodov
Analysis Mathematica, 2021Springer
We present a unified approach to obtain sharp mean-squared and multiplicative inequalities
of Hardy-Littlewood-P�lya and Taikov types for multiple closed operators acting on Hilbert
space. We apply our results to establish new sharp inequalities for the norms of powers of
the Laplace-Beltrami operators on compact Riemannian manifolds and derive the well-
known Taikov and Hardy-Littlewood-P�lya inequalities for functions defined on the d-
dimensional space in the limit case. Other applications include the best approximation of�…
Abstract
We present a unified approach to obtain sharp mean-squared and multiplicative inequalities of Hardy-Littlewood-P�lya and Taikov types for multiple closed operators acting on Hilbert space. We apply our results to establish new sharp inequalities for the norms of powers of the Laplace-Beltrami operators on compact Riemannian manifolds and derive the well-known Taikov and Hardy-Littlewood-P�lya inequalities for functions defined on the d-dimensional space in the limit case. Other applications include the best approximation of unbounded operators by linear bounded ones and the best approximation of one class by elements of another class. In addition, we establish sharp Solyar type inequalities for unbounded closed operators with closed range.
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