  This is a truncated version of the paper "Degenerate diffusion with a drift
potential: a viscosity solutions approach", co-authored with I. C. Kim. The
purpose of this version is to withdraw the claim of quantitative rate of
convergence of the free boundary on the part of H. K. Lei. The difference from
the previous version lies in Section 3 where 1) the quantitative version of the
convergence of the free boundary statement has been removed and 2) the more
basic version of some convergence of the free boundary given uniform
convergence of the function has been rewritten.
  It is emphasized that while some effort has been made towards better
exposition and clarity with regard to showing some convergence of the free
boundary given uniform convergence of the function (see Section 3) there is no
new result here. Quite on the contrary, as the title indicates, what is
contained here is a strict subset of the original.
  We introduce a notion of viscosity solution for a nonlinear degenerate
diffusion equation with a drift potential. We show that our notion of solution
coincides with that of the weak solu- tion defined via integration by parts. As
an application of the viscosity solutions theory, we show that in the case of a
strictly convex potential, the free boundary uniformly converges to equilibrium
as $t$ grows.
