On the automorphism groups of algebraic bounded domains

Abstract

Let $D$ be a bounded domain in $C^n$. By the theorem of H.~Cartan, the group $Aut(D)$ of all biholomorphic automorphisms of $D$ has a unique structure of a real Lie group such that the action $Aut(D)\times D\to D$ is real analytic. This structure is defined by the embedding $C_v:Aut(D)\hookrightarrow D\times G{l}_n(C)$, $f\mapsto (f(v),f_{\ast v})$, where $v\in D$ is arbitrary. Here we restrict our attention to the class of domains $D$ defined by finitely many polynomial inequalities. The appropriate category for studying automorphism of such domains is the Nash category. Therefore we consider the subgroup $Au{t}_a(D)\subset Aut(D)$ of all algebraic biholomorphic automorphisms which in many cases coincides with $Aut(D)$. Assume that $n>1$ and $D$ has a boundary point where the Levi form is non-degenerate. Our main result is theat the group $Au{t}_a(D)$ carries a unique structure of an affine Nash group such that the action $Au{t}_a(D)\times D\to D$ is Nash. This structure is defined by the embedding $C_v:Au{t}_a(D)\hookrightarrow D\times G{l}_n(C)$ and is independent of the choice of $v\in D$.

29 pages, LaTeX, Mathematischen Annalen, to appear