Affine open subsets in A^3 without the cancellation property
  We give families of examples of principal open subsets of the affine space \mathbb{A}^{3} which do not have the cancellation property. We show as a by-product that the cylinders over Koras-Russell threefolds of the first kind have a trivial Makar-Limanov invariant. 
Adrien Dubouloz (IMB)
math.AG