Decision Table Errors

As discussed in the previous section, each rule in a decision table should be different. A decision table is referred to as mechanically perfect when all contradictions and redundancies are removed. In this section we'll review a few examples of common errors occurring in decision tables.

Table 1 itemizes the tools available in LogicGem to automatically uncover common decision table errors.
 
Incompleteness: Not all conditions are covered.
Contradiction: Two rules with the same conditions lead to different actions.
Redundancy: Two rules with the same conditions lead to the same action.
Ambiguity: A reduced table with contradictory and/or redundancy errors.
 
Figure 5 shows a decision table exhibiting examples of redundant, contradictory and ambiguous rules:
 
Figure 5
 
Rule 4 and Rule 5 are redundant since the both contain the same conditions and action.

Rule 4 and Rule 5 are contradictory to Rule 6 since the same conditions map to different actions.

Rule 1 and Rule 7 are ambiguous since their conditions, when considering the "don't cares," overlap with different actions.