Betrachte

${\displaystyle \varphi \colon \mathbb {C} ^{3}\longrightarrow \mathbb {C} ^{3},\,(x,y,z)\longmapsto (x-2(xz+y^{2})y-(xz+y^{2})^{2}z,y+(xz+y^{2})z,z).}$

${\displaystyle {}\varphi }$

${\displaystyle {}y^{2}+xz}$