Missing is a logic engineering tool used to indicate whether any rules are missing in a decision table and then adds the rules to complete the table. The added rules, however, are only in simple form (i.e. no complex rule optimizations are done). This function does not affect the rules that already exist in the table when it is invoked. The Missing rule is of tremendous value in helping to fill out the structure of large logic tables. One approach to logic table design is to start with a few well known rules, and then use the Missing function to help identify all remaining rules. One of the main strengths of LogicGem is that it contains tools like Missing to help you become aware of less well known rules that are required to make the logic table complete. If you use the Missing function on a logically complete table, no action is taken.

 

 

Consider the example table shown above. The logic engineer is building a new table, but can only identify two well known complex rules. The engineer might have developed a case of "logic block" and can't easily think of any other rules. This is where the Missing function comes in handy, and as shown, 4 additional rules are discovered. Figure 20 shows the same decision table, but this time with all missing rules included. From here, the task is to determine the action entries to complete the rules. Along the way of course, the missing rules may be consolidated into fewer complex rules.

 

 

The Logic menu also includes a subset of the Missing function called "…One Rule at a Time" which identifies missing rules, but adds them to the decision table one at a time. You can use this function multiple times in succession to reveal all the missing rules. In larger tables, it may be less overwhelming to present just one missing rule at a time.