The Complex Sobolev Space and Holder continuous solutions to Monge-Amp`ere equations

Let $X$ be a compact Kahler manifold of dimension $n$ and $omega$ a Kahler form on $X$. We consider the complex Monge-Amp`ere equation $(dd^c u+omega)^n=mu$, where $mu$ is a given positive measure on $X$ of suitable mass and $u$ is an $omega$-plurisubharmonic function. We show that the equation admits a Holder continuous solution {it if and only if} the measure $mu$, seen as a functional on a complex Sobolev space $W^*(X)$, is Holder continuous. A similar result is also obtained for the complex Monge-Amp`ere equations on domains of $mathbb{C}^n$.