Locally nilpotent derivations and automorphism groups of certain Danielewski surfaces

Abstract

We describe the set of all locally nilpotent derivations of the quotient ring K[X,Y, Z]/(f (X)Y - phi(X, Z)) constructed from the defining equation f (X)Y = phi(X, Z) of a generalized Danielewski surface in K-3 for a specific choice of polynomials f and phi, with K an algebraically closed field of characteristic zero. As a consequence of this description we calculate the ML-invariant and the Derksen invariant of this ring. We also determine a set of generators for the group of K-automorphisms of K[X, Y, Z]/(f (X)Y- phi(Z)) also for a specific choice of polynomials f and phi. (C) 2016 Elsevier Inc. All rights reserved.