Uniqueness of ${\mathbf{C}}^{\ast }$- and ${\mathbf{C}}_{+}$-actions on Gizatullin surfaces

Hubert Flenner, Shulim Kaliman, Mikhail Zaidenberg

A Gizatullin surface is a normal affine surface $V$ over $\mathbf{C}$, which can be completed by a zigzag; that is, by a linear chain of smooth rational curves. In this paper we deal wi…