Proper $G_a$-actions on $\C^4$ preserving a coordinate

Abstract

We prove that the actions mentioned in the title are translations. We show also that for certain $G_a$-actions on affine fourfolds the quotient of the action is automatically affine and describe the geometric structure of such quotients.

34 page

References in corpus (2)

• Birational splitting and algebraic group actions
• Proper triangular Ga-actions on A^4 are translations