English

Exact estimates of high-order derivatives in Sobolev spaces

Functional Analysis 2022-08-29 v1

Abstract

The paper describes the splines Qn,k(x,a)Q_{n,k}(x,a), which for an arbitrary point a(0;1)a\in(0;1) and an arbitrary function yW˚pn[0;1]y\in\mathring{W}^n_p[0;1] set the relations y(k)(a)=01y(n)(x)Qn,k(n)(x,a)dxy^{(k)}(a)=\int_0^1 y^{(n)}(x)Q^{(n)}_{n,k}(x,a)dx. The relation of the Lp[0;1]L_{p'}[0;1] norm minimization for Qn,k(n)Q^{(n)}_{n,k} (1/p+1/p=11/ p+1/p'=1) with the problem of the best estimates of derivatives of y(k)(a)An,k,p(a)y(n)Lp[0;1]y^{(k)}(a)\leqslant A_{n,k,p}(a)\|y^{(n)}\|_{L_p[0;1]}, and also with the problem of finding the exact embedding constants of the Sobolev space W˚pn[0;1]\mathring{W}^n_p[0;1] into the space W˚k[0;1]\mathring{W}^k_\infty[0;1], nNn\in\mathbb{N}, k=0,1,,n1k=0,1,\ldots, n-1. Exact embedding constants are found for k=n1k=n-1 and p=p=\infty, as well as for all nNn\in\mathbb{N}, k=0,1,,n1k=0,1,\ldots, n-1 and p=1p=1.

Keywords

Cite

@article{arxiv.2208.12791,
  title  = {Exact estimates of high-order derivatives in Sobolev spaces},
  author = {T. A. Garmanova and I. A. Sheipak},
  journal= {arXiv preprint arXiv:2208.12791},
  year   = {2022}
}

Comments

2 figures, in Russian language