Holomorphic mappings preserving Minkowski functionals

Abstract

We show that the equality $m_1(f(x))=m_2(g(x))$ for $x$ in a neighborhood of a point $a$ remains valid for all $x$ provided that $f$ and $g$ are open holomorphic maps, $f(a)=g(a)=0$ and $m_1,$ $m_2$ are Minkowski functionals of bounded balanced domains. Moreover, a polynomial relation between $f$ and $g$ is obtained. Next we generalize these results to bounded quasi-balanced domains. Moreover, the main results of \cite{Ber-Piz} and \cite{Bou} are significantly extended and their proofs are essentially simplified.