Compressing the example in the preceding topic into a recognizable pattern, however, has an interesting side effect: it introduced more subrules than were initially present. To see this, click Expand to compress the Rulesheet as shown:

Figure 1. Expanding Rules following compression

You may be surprised to see a total of 54 subrules (columns) displayed (in the preceding figure) instead of the 26 prior to compression. Look closely at the 54 columns, and you will see several instances of subrule redundancy. Of the 18 sub-rules within the original columns 2, 3 and 4, almost half are redundant (for example, subrules 2.1, 3.1 and 4.1, shown in the preceding figure, are identical). What happened?