Distance-Weighted Norm Equivalences for Analytic Functions on John Domains

Abstract

Let $Ω\subset\mathbb C$ be a bounded John domain and set $δ(z)=\text{dist}(z,\partialΩ)$. For $1<p<\infty$ and $α>\text{dim}_A(\partialΩ)-2$, we establish a norm equivalence between $\int_Ω|g|^pδ^α\,dA$ and $\int_Ω|g&#39;|^pδ^{α+p}\,dA$ for analytic functions $g$ on $Ω$, with a point-evaluation term fixing the additive constant. The estimate of the derivative term is local and holds on every proper planar domain, whereas the converse follows from a distance-weighted Poincaré inequality on John domains. Taking $α=mp-2$ yields the corresponding comparison between the $m$-th and $(m+1)$-st derivatives. For $m\ge2$ the boundary-dimension condition is automatic, so the only dimension-sensitive case is the comparison between $\int_Ω|f&#39;|^pδ^{p-2}\,dA$ and $\int_Ω|f&#39;&#39;|^pδ^{2p-2}\,dA$ when $1<p<2$. We show that this restriction is sharp within the class of quasidisks by using self-similar Rohde snowflakes. We also construct, for every $s>1$, an inward-cusp $s$-John domain on which the comparison fails, showing that the ordinary John condition cannot in general be weakened.