Advanced Search

The present paper is devoted to the study of the “quality” of the compactness of the trace operator. More precisely, we characterize the asymptotic behaviour of entropy numbers of the compact map $t{r}_{\Gamma }:B_{p₁,q}^s(ℝⁿ,w_{\varkappa }^{\Gamma })\to L_{p₂}\left(\Gamma \right)$, where Γ is a d-set with 0 < d < n and $w_{\varkappa }^{\Gamma }$ a weight of type $w_{\varkappa }^{\Gamma }\left(x\right)dist{(x,\Gamma )}^{\varkappa }$ near Γ with ϰ > -(n-d). There are parallel results for approximation numbers.

The main purpose of the present paper is to extend the theory of non-smooth atomic decompositions to anisotropic function spaces of Besov and Triebel-Lizorkin type. Moreover, the detailed analysis of the anisotropic homogeneity property is carried out. We also present some results on pointwise multipliers in special anisotropic function spaces.