Bounded Point Evaluations For Certain Polynomial And Rational Modules
Functional Analysis
2019-03-21 v1
Abstract
Let K be a compact subset of the complex plane C. Let P(K) and R(K) be the closures in C(K) of analytic polynomials and rational functions with poles off K, respectively. Let A(K)⊂C(K) be the algebra of functions that are analytic in the interior of K. For 1≤t<∞, let Pt(1,ϕ1,...,ϕN,K) be the closure of P(K)+P(K)ϕ1+...+P(K)ϕN in Lt(dA∣K), where dA∣K is the area measure restricted to K and ϕ1,...,ϕN∈Lt(dA∣K). Let HP(ϕ1,...,ϕN,K) be the closure of P(K)ϕ1+...+P(K)ϕN+R(K) in C(K), where ϕ1,...,ϕN∈C(K). In this paper, we prove if R(K)=C(K), then there exists an analytic bounded point evaluation for both Pt(1,ϕ1,...,ϕN,K) and HP(ϕ1,...,ϕN,K) for certain smooth functions ϕ1,...,ϕN, in particular, for zˉ,zˉ2,...,zˉN. We show that A(K)⊂HP(zˉ,zˉ2,...,zˉN,K) if and only if R(K)=A(K). In particular, C(K)=HP(zˉ,zˉ2,...,zˉN,K) unless R(K)=C(K). We also give an example of K showing the results are not valid if we replace zˉn by certain ϕn, that is, there exist K and a function ϕ∈A(K) such that R(K)=A(K), but A(K)=HP(ϕ,K).
Cite
@article{arxiv.1711.03715,
title = {Bounded Point Evaluations For Certain Polynomial And Rational Modules},
author = {Liming Yang},
journal= {arXiv preprint arXiv:1711.03715},
year = {2019}
}