Expand is a logic engineering tool used to create the simple rules to represent all possible true/false combinations of conditions in the table.  If action entries exist, then they will be expanded as well. The Expand function is useful when starting to fill out condition entries as it provides a big picture of the extent of the logic. Of course, a decision table with many conditions may yield a very large expanded table. One approach towards rule determination is to start with a fully expanded table, and then incrementally identify candidate rules for consolidation into few complex rules. After a series of iterations, a table of 64 expanded rules, for example, could be narrowed down to less than 10 rules.

NOTE: Invoking the Expand function may delete and replace previously entered rules.

Figure 18 shows an expanded version of our sample logic table which has only 4 complex rules in optimized form. The expanded table has 8 rules or 23 based on three conditions.