Constructing almost rigid rings and a UFD having infinitely generated Derksen and Makar-Limanov invariant - Mathematics > Algebraic Geometry

Abstract: An example is given of a UFD which has infinitely generated Derkseninvariant. The ring is \textquotedblleft almost rigid\textquotedblright\meaning that the Derksen invariant is equal to the Makar-Limanov invariant.Techniques to show that a ring is almost rigid are discussed, among which isa generalization of Mason-s abc-theorem.

Author: David Finston, Stefan Maubach

Source: https://arxiv.org/