We extend the classical theorems of I. I. Privalov and A. Zygmund from single to multiple conjugate functions in terms of the multiplicative modulus of continuity. A remarkable corollary is that if a function f belongs to the multiplicative Lipschitz class for some and its marginal functions satisfy for some uniformly in the indicated variables , 1 ≤ l ≤ N, then for each choice of with or 1 for 1 ≤ l ≤ N.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-cm115-1-3,
author = {Ferenc M\'oricz},
title = {Multiple conjugate functions and multiplicative Lipschitz classes},
journal = {Colloquium Mathematicae},
volume = {116},
year = {2009},
pages = {21-32},
zbl = {1160.42004},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm115-1-3}
}
Ferenc Móricz. Multiple conjugate functions and multiplicative Lipschitz classes. Colloquium Mathematicae, Tome 116 (2009) pp. 21-32. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm115-1-3/