\documentclass{article}
\input tmp.inputs
\pagestyle{empty}
\usepackage{amssymb,amsbsy}
\begin{document}
$ \IR^3 = \left\{ {\psframebox*[fillcolor=darkyellow,  linestyle=none]{{\left( {a_1 , \ldots \rnode[t]{ae},a_n } \right)}}}
{|a_1 , \ldots a_n  \in \IR} \right\} $\\[5mm] %
\rnode{a}{n-Tupel}%
\nccurve[angleA=-45]{->}{a}{ae}
\end{document}
