!- Converted with LaTeX2HTML 0.6.4 (Tues Aug 30 1994) by Nikos Drakos (firstname.lastname@example.org), CBLU, University of Leeds ->
The following illustrate the effect of applying variable substitution.
The above expression has been annotated with underbraces to indicate the variable substitution that is performed. Notice that applying variable substitution reveals the recursive nature of the expression. It is interesting to note that if we now run our algorithm on this annotated expression, the subexpressions marked by underbraces are chosen for substitution.