The Riemann Mapping Problem

In this article we investigate the century-old continuous extension problem of the Riemann map. Let $G$ be a simply connected domain. We call $\lambda$ in $\partial G$ a multiple point if there are simply connected subdomains $U$ and $V$ such that $\lambda \in\partial U \cap\partial V$ and $dist (\partial U\cap G , \partial V\cap G )>0$. We show that the Riemann map of $G$ has a continuous extension to $\overline G$ if and only if $\partial G$has no multiple points. All of the results in this paper, together with the Riemann mapping theorem, give a complete and desirable solution to the mapping problem that was originally raised by Riemann in 1851 and intensively investigated by many famous mathematicians throughout history.