We obtain sharp bounds for the monotonic rearrangement operator from "dyadic-type" classes to "continuous" ones; in particular, for the BMO space and Muckenhoupt classes. The idea is to connect the problem with a simple geometric construction named α-extension.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-sm8326-2-2016, author = {Dmitriy M. Stolyarov and Vasily I. Vasyunin and Pavel B. Zatitskiy}, title = {Monotonic rearrangements of functions with small mean oscillation}, journal = {Studia Mathematica}, volume = {231}, year = {2015}, pages = {257-267}, zbl = {06575016}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm8326-2-2016} }
Dmitriy M. Stolyarov; Vasily I. Vasyunin; Pavel B. Zatitskiy. Monotonic rearrangements of functions with small mean oscillation. Studia Mathematica, Tome 231 (2015) pp. 257-267. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-sm8326-2-2016/