How do you handle complex or conflicting rules in decision tables and trees?

1 What are decision tables and trees?

Decision tables and trees are graphical representations of the conditions and actions that make up a business rule or a use case scenario. A decision table consists of rows and columns that show the combinations of conditions and the corresponding actions. A decision tree is a diagram that shows the branching paths of conditions and actions. Both tools can help you to simplify and organize the requirements, as well as to test and verify them.

3 How to handle complex rules or scenarios?

Sometimes, you may encounter rules or scenarios that are too complex or ambiguous to fit into a single row or node of a decision table or tree. For example, you might have multiple actions for the same condition, or multiple conditions for the same action, or nested conditions that depend on each other. To handle these cases, you can use techniques like splitting the rule or scenario into sub-rules or sub-scenarios and creating separate decision tables or trees. Additionally, you can use extended entries or connectors to indicate that there are more conditions or actions that are not shown in the table or tree. Conditional expressions and operators such as AND, OR, NOT, IF, THEN, and ELSE can also be used to combine or modify conditions and actions. Finally, variables and parameters can be used to represent values and states of conditions and actions; these should be defined clearly in the table or tree.

4 How to handle conflicting rules or scenarios?

When using decision tables or trees, you may come across conflicting rules or scenarios. These involve different rules or scenarios that have the same or overlapping conditions, but different or contradictory actions. For instance, a rule may state that a 10% discount should be given to VIP customers, while another rule may say that a 15% discount should be given to VIP customers who have orders over $1000. To resolve these cases, you can prioritize the rules or scenarios based on their importance, urgency, frequency, or specificity and apply them in that order. Additionally, exceptions or exclusions can be used to specify the conditions or actions that override or cancel out the other rules or scenarios. Default or fallback actions can also be employed to handle cases where none of the rules or scenarios match. Lastly, feedback or confirmation can be requested from the user or system to choose or verify the actions in case of conflict.

5 How to test and validate decision tables and trees?

Once you have created your decision tables or trees, it is essential to test and validate them to guarantee they are complete, correct, consistent, and clear. You can review the tables or trees with stakeholders, users, developers, testers, and other relevant parties to get their feedback and approval. Additionally, it is important to check for any errors, gaps, redundancies, ambiguities, or contradictions and revise them accordingly. You can also use test cases or scenarios based on the rules or scenarios in the tables or trees to compare the expected and actual outcomes. Additionally, you can use tools or software that can generate, execute, or automate the tests based on the tables or trees.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?