Zum Beweis einer Jackson-Typ-Ungleichung mit Hilfe spezieller Kommutatoren

Abstract

We study the commutators of some differential operators and operators connected with the error of approximation for proving an inequality of Jackson-type for trigonometrical polynomials in a scale of (anisotropic) Sobolev spaces (with weight). The results are applicable to construct systems of functions with high degree approximation satisfying given boundary conditions.