Berisha, M. Q.; Berisha, F. M. A note on the inverse theorem for a generalised modulus of smoothness. (English) Zbl 1274.42001 Mat. Bilt. 25, 91-96 (2001). Summary: We prove the converse to Jackson’s theorem for a modulus of smoothness of first order generalised by means of an asymmetric operator of generalised translation. MSC: 42A05 Trigonometric polynomials, inequalities, extremal problems 42A10 Trigonometric approximation Keywords:generalised modulus of smoothness; asymmetric operator of generalised translation; converse Jackson theorem; best approximation by algebraic polynomials PDF BibTeX XML Cite \textit{M. Q. Berisha} and \textit{F. M. Berisha}, Mat. Bilt. 25, 91--96 (2001; Zbl 1274.42001) Full Text: arXiv OpenURL