decisiontable

A decision table is a tabular representation of decision logic that maps combinations of conditions to actions or outcomes. It is used in business rule management, software engineering, and decision modeling to make rule sets explicit, auditable, and easier to validate. A typical decision table consists of a header that defines condition columns (for example age > 18, has account balance) and action or result columns (for example allow purchase, require verification). The body of the table enumerates rule rows. Each row assigns truth values or value ranges to the condition columns and specifies the corresponding actions or outputs when those conditions are met. Some tables include alternative representations such as decision tables with multiple outputs or with ranges and constraints in the condition entries.

In practice, decision tables aid collaboration between business analysts and developers and are used as a bridge between policy and implementation. They are common in rule engines and in decision modeling approaches such as DMN, where a decision table uses input data, input entries, output entries, and a hit policy to govern evaluation order (for example first-match or all-matches).

Quality considerations include ensuring completeness (every relevant combination is covered), avoiding contradictions, and eliminating redundancies. A simple example: if income > 50,000 and credit score > 700 then approve loan; if income > 50,000 and credit score <= 700 then require manual review; if income <= 50,000 then deny.