New characterization of Hardy-Fofana spaces and temperature equation
Martial Agbly Dakoury, Justin Feuto
TL;DR
The paper addresses characterizing Hardy-Fofana spaces $\\mathcal{H}^{(p,q,\alpha)}(\\mathbb{R}^d)$ through Riesz transforms and by viewing their elements as boundary values of bounded solutions to generalized Cauchy-Riemann (temperature) equations. It develops a Riesz-transform framework and a temperature-CR PDE approach, establishing equivalences between maximal-function criteria, harmonic extensions, and boundary data in $$(L^p,\\ell^q)^{\\alpha}$$-type spaces, including a topological isomorphism with a temperature Hardy-type space. The main contributions are (i) a complete CR/Riesz characterization for Hardy-Fofana spaces and (ii) a robust dilation-invariant temperature-CR description via an explicit heat-kernel mapping that links $\\mathcal{H}^{(p,q,\alpha)}(\\mathbb{R}^d)$ with $\\mathbb{H}^{(p,q,\alpha)}(\\mathbb{R}^{d+1}_+)$. This framework clarifies boundary behavior, operator mappings, and provides a PDE-analytic perspective that extends known results from Hardy-Amalgam spaces to the Hardy-Fofana setting, potentially aiding applications requiring precise function-space control under dilations and transforms.
Abstract
The aim of this paper is to give a characterization of Hardy-Fofana spaces via Riesz trasforms. This characterization allow us to describ the distributions belonging to these spaces as a bounded solutions of Cauchy-Riemann's general temperature equations.
