Inverse Jackson theorems in spaces with integral metric

  • S. A. Pichugov Днепропетр. нац. ун-т ж.-д. трансп.


In the spaces $L_{\Psi}(T)$ of periodic functions with metric $\rho(f, 0)_{\Psi} = \int_T \Psi(|f(x)|)dx$, where $\Psi$ is a function of the modulus-of-continuity type, we investigate the inverse Jackson theorems in the case of approximation by trigonometric polynomials. It is proved that the inverse Jackson theorem is true if and only if the lower dilation exponent of the function $\Psi$ is not equal to zero.
How to Cite
Pichugov, S. A. “Inverse Jackson Theorems in Spaces With Integral Metric”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 64, no. 3, Mar. 2012, pp. 351-62,
Research articles