Estimates for Kolmogorov and Gelfand n-widths of multiplier operators of multiple Walsh series are obtained. Upper and lower bounds are established for n-widths of general multiplier operators. These results are applied to get upper and lower bounds for n-widths of specific multiplier operators, which generate sets of finitely and infinitely differentiable functions in the dyadic sense. It is shown that these estimates have order sharp in various important cases.
Sergio A. Córdoba
Sérgio A. Tozoni
n-widths, multipliers operators, multiple Walsh series, approximation th