Sufficient condition for boundedness of maximal operator on weighted generalized Orlicz spaces
Vertti Hietanen
TL;DR
The paper establishes a sufficiency condition for the boundedness of the Hardy-Littlewood maximal operator on weighted generalized Orlicz spaces $L^oldsymbol{ extphi}(oldsymbol{ extOmega},oldsymbol{ extomega})$. The result requires the weight to satisfy a Muckenhoupt condition $oldsymbol{ extomega} in A_p$ and the modular to obey the almost-increasing property $(aInc)_p$ in addition to standard $oldsymbol{ extphi}$-conditions, unifying unweighted and weighted theories. The core method treats the weight as a measure and derives a weighted Jensen-type key estimate, extending the classical $A_1$/$A_2$ framework to weighted variants $A1_w$, $A2_w$, which then yields the boundedness via the unit ball property. The findings apply to important special cases, including variable exponent spaces and double-phase functionals, under natural regularity like log-H"older continuity/decay and Nekvinda-type conditions, broadening the applicability of maximal operator bounds in Musielak-Orlicz settings.
Abstract
We prove that the Hardy-Littlewood maximal operator is bounded in the weighted generalized Orlicz space if the weight satisfies the classical Muckenhoupt condition $A_p$ and $t \to \frac{\varphi(x,t)}{t^p}$ is almost increasing in addition to the standard conditions.
