Dou Xie

A Hardy-Littlewood type Theorem and a Heinz type inequality

The main aim of this paper is to investigate the Hardy-Littlewood type Theorem and the Heinz type inequality on functions induced by a differential operator. We first prove a more general Hardy-Littlewood type theorem for the Dirichlet solution of a differential operator which depends on $α>0$ over the unit ball $\mathbb{B}^n$ of $\mathbb{R}^n$ with $n\geq 2$, related to the Lipschitz type space defined by a fast majorant. We find that the case $α>0$ is completely different from the case $α=0$. Then a more general Heinz type inequality for the Dirichlet solution of a differential operator will also be established in the case $α>n-2$.