English

Lower bounds for Kolmogorov widths of classes of convolutions with Neumann kernel

Classical Analysis and ODEs 2013-12-24 v1

Abstract

We obtain exact lower bounds for Kolmogorov nn-widths in spaces CC and LL of classes of convolutions with Neumann kernel Nq,β(t)=k=1qkkcos(ktβπ2)N_{q,\beta}(t)=\sum\limits_{k=1}^{\infty}\dfrac{q^k}{k}\cos\left(kt-\dfrac{\beta\pi}{2}\right), q(0,1){q\in(0,1)}, βR{\beta\in\mathbb{R}}, for all natural nn greater some number which depend only on qq. The obtained estimates coincide with the best uniform approximations by trigonometric polynomials of mentioned classes. It made possible to obtain exact values for widths of these classes.

Keywords

Cite

@article{arxiv.1312.6175,
  title  = {Lower bounds for Kolmogorov widths of classes of convolutions with Neumann kernel},
  author = {V. V. Bodenchuk},
  journal= {arXiv preprint arXiv:1312.6175},
  year   = {2013}
}

Comments

21 pages, in Ukrainian