Page 247, Exercise 1
The transformation of a tree into a forest can be defined as follows:
If T is a Tree with Root R, then the Forest F corresponding to this tree is denoted by T1 .. Tn+1:
(1) is empty, if R is null.
(2) T1  has root equal to R, and children equal to C1 .. Cn, where C1 .. Cn are the children of R in T.
(3) T2 .. Tn+1 are trees consisting of the descendants of C1 .. Cn  in T.  Tk is empty if Ck has no descendants in T.
The transformation is unique only in that T2 must match the descendants of C1, and so on.  The initial ordering of the children in T is irrelevant.