On \(N\)-widths of holomorphic functions of several variables
The author calculates linear and Gel'fand \(N\)-widths of certain classes of holomorphic functions by considering them as subsets of the normed linear spaces \(C(S_\rho)\), \(C(T^n_\rho)\) or \(C(\Delta_\rho)\), where \(S_\rho\), \(T^n_\rho\) and \(\Delta_\rho\) are the following sets: \[ \begin{aligned} S_\rho &:= \{z\in \mathbb{C}^n:\;|z|= \rho\},\\ T^n_\rho &:= \{z:= (z_1, \dots, z_n)\in \mathbb{C}^n:\;|z_1|= \rho_1, \dots, |z_n|= \rho_n\},\\ \Delta_\rho &:= \{z\in \mathbb{C}:\;\rho^{-1}< |z|< \rho\}. \end{aligned} \] {}.
scientific article; zbMATH DE number 782148