2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/132608The automorphism groups of certain factorial complex affine threefolds admitting locally trivial actions of the additive group are determined. As a consequence new counterexamples to a generalized cancellation problem are obtained.To appear in Isr. J. MathAlgebraic GeometryCommutative Algebra13N15,13A50,14R20The Automorphism Group of Certain Factorial Threefolds and a Cancellation Problemtext