Study guide: Compose and Test Boolean Rules
Use truth tables, grouping and counterexamples to check fictional decision policies.
Ideas to explain in your own words
- Translate a stated access rule into Boolean logic using fictional roles.
- Evaluate an explicitly parenthesized combination of AND, OR and NOT.
- Use every Boolean input combination to compare two expressions.
- Translate a stated fictional policy and prioritize its explicit blocking condition.
Watch your reasoning
- False AND true is false. Both inputs are supplied, and the rule requires both. “One is enough” would describe OR, which is a different rule.
- The key/pass OR is true, and NOT paused is also true, so their AND is true.
- At false,true, NOT OR is false while NOT AND is true. The all-false and all-true pairs give matching outputs and would miss the difference.
- The policy requires false when blocked is true. Only the supplied token-true blocked case makes the faulty token OR expression return true instead.
A worked review example
Trace an AND condition: Case A gives true AND false = false, so the door stays closed. Case B gives true AND true = true. A running timer alone also fails the AND rule. Group a Boolean Expression: (true, false, false): true OR false = true; NOT false = true; true AND true = true. (false, true, true): first group true, NOT paused false, result false. (false, false, false): first group false, result false. Check Whether Two Rules Are Equivalent: R outputs true, false, false, false. S outputs true, false, false, false, so they are equivalent for all four Boolean pairs. NOT (A AND B) outputs true, true, true, false and is different. Trace a Rule with a Blocking Flag: For (blocked,token,pass) = (true,true,false), correct rule returns false immediately. Faulty rule gives true OR (false AND false) = true. Unblocked with token false/pass true returns true; unblocked with both false returns false.
Make a practice plan
- Try the supplied lesson problems without looking at the answers.
- Compare your method with the worked examples and explain any correction.
- Use the new review cases, then complete the transfer task on paper or in your own document.