a1 Department of Mathematics, UNC Chapel Hill, NC 27599, USA (email: firstname.lastname@example.org)
a2 Department of Mathematics, Shippensburg University, PA 17257, USA (email: email@example.com)
This paper is an update and extension of a result the authors first proved in 2003. The goal of this paper is to study factors which are known to be L2-characteristic for certain non-conventional averages and prove that these factors are pointwise characteristic for the multiterm return times averages.
(Received December 14 2010)
(Revised August 29 2011)
(Online publication December 01 2011)
In memory of Dan Rudolph