Informally, an edit script gives a sequence of edit operations that
transforms one tree into another. Formally, we say 
when 
is the result of applying
the edit operation 
to 
. Given a sequence 
of edit operations, we say 
if there exist 
such that 
. A sequence E of edit
operations transforms 
into 
if 
and 
is isomorphic to
. (Recall that two trees are isomorphic if they differ only in
the identifiers of their nodes.) We call such a sequence of edit
operations an edit script of 
with respect to 
.
Notice that an edit script does not tell us how the original matching
between 
and 
should be modified to obtain the total
matching between 
and 
. This will be done as the edit
script is generated; see Section 4.
: Applying the edit script of Example 3.1
