On the perfection of schemes
  This is a chiefly expository paper on the subject of the title which, in our view, has not received a detailed treatment in the literature which is commensurate with its importance. We expect the results presented here to be useful in a number of contexts. For example, several of them will be applied in a forthcoming paper by the authors. 
Alessandra Bertapelle and Cristian D. Gonzalez-Aviles
math.AG math.NT