The user starts with an NFA, and then enters the starting recursive formula. A table is then displayed showing all the formulas that must be calculated. Since filling out the formulas is a bit tedious and straight forward, the user can choose to either have the formulas all filled out, or step through the filling out of the formulas. At the bottom of recursion and on the way back out of recursion, the formulas are replaced by regular expressions. The first expressions are fairly simple, and the user can either type them in or have them displayed.
Later formulas can result in rather long regular expressions.
The user is asked to simplify these regular expressions. Here are some of the rules that are used in the simplifications of regular expressions. Not all rules are shown. For example, Figure 4 shows part of the working window of the conversion of the NFA shown in Figure 3 to a regular expression. Since the components of its right-hand side have already been calculated, the line immediately below fills them in with their regular expressions.