Decision Modeling with Decision Table Systems

19 important questions on Decision Modeling with Decision Table Systems

Mention some ways in which you can represent rule sets.

- Just plain text
- Decision tables
- Decision trees 
- (Binary) decision diagrams
- Action diagrams
- Nested-If-Then-Else
- Text
- Spreadsheets

What is a decision table?

A decision table is a table representing the complete set of mutually exclusive conditional expressions in a predefined area.

Other: decision rules in a tabular format

Which two criteria does a decision table have?

- Completeness criteria: all combinations should be present
- Exclusivity criteria: columns should not overlap
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What is the difference between horizontal, vertical, and crosstabl decision tables?

Horizontal decision tables have the rules in rows.
Vertical decision tables have the rules in column.
Crosstab decision tables have the rules in a combination of both ways.

Why would you use decision tables?

- Powerful visualisation: compact and structured representation
- Preventing errors is easier: avoid incompleteness and inconsistency
- Modular knowledge organization: group related rules into single table
- Decision Performance if necessary: fast decision tree execution

What types of tables exist?

- Unique single hit tables: no overlapping rows
- Tables with redundancy/Any tables: Overlapping rows but with the same conclusion
- First-hit tables: overlapping rows but with different conclusions
- Multiple-hit tables/All hits tables: overlapping rows but with different conclusions

What is the difference between multiple and single hit tables?

In multiple hit you want multiple rules to succeed.
In single hit you want one rule as a result.

What are optimization features for tables?

- Table contraction: merge adjacent columns or column groups with identical action parts (leads to a contracted table)
- Row order optimization: less columns by changing order of condition rows

What is execution time optimization?

This determines the optimal test sequences (output is an execution tree). It takes (if available) the test times and column frequencies into account. If these are not available they are assumed equal.

What is Decision table methodology (DTM)?

It mentions how to use a constrained form of decision tables in order to model decisions. It is goal-oriented decision modeling network. It is a good decision table design. It is meant for single hit tabes, relations between tables, table notation, contraction, optimization, and normalization.

What is Decision Modeling & Notation (DMN) standard?

It is a standard syntax and notation for exchange. It recognizes other forms of tables. You can combine tables with other concepts in decision modeling with this DMN. It is a standard expression language.

What is the difference between the global model and the detailed model?

The global model gives an hierarchy of the decision tables. The detailed model is a decision table of the global model, but them zoomed in, such that you can see the details of the table.

In which three ways can you model the overall structure?

Top-down, bottum-up, and factoring (you can use normalization for decision tables in factoring).

What three methods exist for modeling the tables? Explain them.

- The interactive method: decision elicitation, interview sessions
- The direct (construction) method: completeness and consistency by design
- Decision logic mining: rule mining and representation

What are the different steps in the direct constuction method for a decision table?

1. Define the conditions, the condition values (exclusive and complete) and the actions
2. Construct the empty table: list the conditions and the actions, then fill out the condition entries of the table --> completeness and consistency by design
3. Describe the problem using (logical) expressions, where actions and (combinations of) condition states are related
4. Fill out the action entries (column by column or action by action), based on the logical expressions
5. Check the table for correctness and consistency
6. Simplify the decision table

What are the different purposes for using decision tables?

- Specification: description and modeling
- Verification and validation: there exists inter-tabular verification in which you verify each table. And there exists inter-tabular verification in which you verify different (sub)tables with respect to each other
- Execution: implementation

In what different areas are decision tables applied?

- Regulation, legislation, compliance
- Business rules, corporate policy
- Business Process Management
- Knowledge and expertise
- Classification knowledge
- System analysis and implementation

There are two structures of tables: condition subtables and action subtables. Can you explain the difference?

Condition subtables determine the state of a condition
Action subtables elaborate further on what additional knowledge holds for certain cases

What is the cleanroom approach?

Look at redundancy (which you can avoid by single-hit table mechanism), look at inconsistency or contraditions (which you can avoid by modeling single-hit tables), look at incompleteness (which you can avoid by automatic generation of all combinations) and look at the correctness (it is easy to visualize the decision logic)

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