  In this paper it is established that all two-dimensional polynomial
automorphisms over a regular ring R are stably tame. In the case R is a
Dedekind Q-algebra, some stronger results are obtained. A key element in the
proof is a theorem which yields the following corollary: Over an Artinian ring
A all two-dimensional polynomial automorphisms having Jacobian determinant one
are stably tame, and are tame if A is a Q-algebra. Another crucial ingredient,
of interest in itself, is that stable tameness is a local property: If an
automorphism is locally tame, then it is stably tame.
