A Repeated Filling Scheme for Upcrossings 
Authors: M.A. Akcoglu, J.R. Baxter, S.E. Ferrando. 
Abstract: We develop a Repeated Filling Scheme for Upcrossings in the basic 
case, that is, in the case of the Ratio Ergodic Theorem setting. Our proof will 
be based on a variant of the filling scheme construction used originally by 
Chacon and Ornstein to prove the Maximal Ergodic Lemma. We will also strengthen 
Bishop's result in one direction, since we allow for a more general form of 
upcrossing.