Smoothness and jet schemes
  This paper shows some criteria for a scheme of finite type over an algebraically closed field to be non-singular in terms of jet schemes.   For the base field of characteristic zero, the scheme is non-singular if and only if one of the truncation morphisms of its jet schemes is flat. For the positive characteristic case, we obtain a similar characterization under the reducedness condition on the scheme. We also obtain by a simple discussion that the scheme is non-singular if and only if one of its jet schemes is non-singular. 
Shihoko Ishii