Decision Logic

After this lesson, the reader should understand:

• 01Construct a complete decision structure for a rule set.
• 02Test for unreachable paths and undefined outcomes.
• 03Produce a reasoning trace alongside an outcome.

The eligibility path with no 'no'

An eligibility policy defines who qualifies but never defines refusal. What does the machine do?

Nothing defensible. An incomplete decision structure produces silent defaults, and silent defaults are unlogged policy. Completeness testing surfaces the omission before deployment and forces the institution to state the refusal path explicitly — which is a policy decision the drafters never made in prose.

• Is a default outcome ever acceptable?
• Should evaluation order be part of the authority or an implementation detail?
• How much of the trace should be disclosed to the subject?

Draw and test a decision structure.

1. 01Map every branch from inputs to outcome.
2. 02Identify paths with no defined terminal.
3. 03Identify branches that can never be reached.
4. 04Write the trace a single case would produce.

• Decision tables and DMN.
• Model checking and coverage analysis.
• Explainability in automated decision systems.