Motivated by multiresolution decomposition methods such as the discret
e wavelet transformation, me introduce reciprocal processes on truncat
ed N-ary trees. We discuss the relationship between such processes and
nearest neighbor models. We show that we can derive a recursive descr
iption of the process, and that all reciprocal processes on N-ary tree
s reduce to autoregressive processes in the case of zero-valued bounda
ry values at the bottom of the tree, corresponding to truncation of th
e tree. We then study the smoothing equations associated with such mod
els.