New moduli of smoothness on the unit ball, applications and computability

JOURNAL OF APPROXIMATION THEORY

卷:180

Article

Ditzian, Z.

关键词: Moduli of smoothness;    Orthogonal expansion;    Nikolski and Ul'yanov type inequality;    Best approximation;    Sharp Jackson inequality;    Besov spaces;   

DOI  :  10.1016/j.jat.2013.12.002

来源: Elsevier

【 摘 要 】

In a previous article I introduced new moduli of smoothness on the unit ball and derived their main properties. The usefulness of these moduli is demonstrated here by some applications. Ul'yanov-type inequalities are derived via new Nikolski-type inequalities. Sharp Jackson inequalities are given for some Banach spaces whose unit ball satisfies a certain convexity condition. Connections with appropriate Besov spaces are discussed. Computations of the moduli for some functions are exhibited. This will illustrate the situations and the optimality of the conditions in some theorems as well as demonstrate the computability of the moduli. (C) 2014 Elsevier Inc. All rights reserved.

【 授权许可】

Free