Predual Spaces of Banach Completions of Orlicz-Hardy Spaces Associated with Operators

TL;DR

This paper investigates dual spaces related to Orlicz-Hardy spaces associated with operators, introducing new function spaces and characterizations, and generalizing recent results by considering more general Orlicz functions.

Contribution

The authors define VMO-type and tent spaces linked to operators, characterize these spaces, and identify dual spaces of Orlicz-Hardy spaces, extending prior work to broader Orlicz functions.

Findings

Characterization of VMO-type space via tent space

Identification of dual space of VMO as a Banach completion

Generalization of known results for specific Orlicz functions

Abstract

Let $L$ be a linear operator in $L^2({{\mathbb R}^n})$ and generate an analytic semigroup $\{e^{-tL}\}_{t\ge 0}$ with kernels satisfying an upper bound of Poisson type, whose decay is measured by $\theta(L)\in (0,\infty].$ Let $\omega$ on $(0,\infty)$ be of upper type 1 and of critical lower type $\widetilde p_0(\omega)\in (n/(n+\theta(L)), 1]$ and $\rho(t)={t^{-1}}/\omega^{-1}(t^{-1})$ for $t\in (0,\infty)$. In this paper, the authors first introduce the VMO-type space $\mathrm{VMO}_{\rho,L}({\mathbb R}^n)$ and the tent space $T^{\infty}_{\omega,\mathrm v}({\mathbb R}^{n+1}_+)$ and characterize the space $\mathrm{VMO}_{\rho,L}({\mathbb R}^n)$ via the space $T^{\infty}_{\omega,\mathrm v}({{\mathbb R}}^{n+1}_+)$. Let $\widetilde{T}_{\omega} ({{\mathbb R}}^{n+1}_+)$ be the Banach completion of the tent space $T_{\omega}({\mathbb R}^{n+1}_+)$. The authors then prove that $\widetilde{T}_{\omega}({\mathbb R}^{n+1}_+)$ is the dual space of $T^{\infty}_{\omega,\mathrm v}({\mathbb R}^{n+1}_+)$. As an application of this, the authors finally show that the dual space of $\mathrm{VMO}_{\rho,L^\ast}({\mathbb R}^n)$ is the space $B_{\omega,L}({\mathbb R}^n)$, where $L^\ast$ denotes the adjoint operator of $L$ in $L^2({\mathbb R}^n)$ and $B_{\omega,L}({\mathbb R}^n)$ the Banach completion of the Orlicz-Hardy space $H_{\omega,L}({\mathbb R}^n)$. These results generalize the known recent results by particularly taking $\omega(t)=t$ for $t\in (0,\infty)$.