Logic Puzzles — Revision Notes

⚡ 30-Second Revision

Preserve the direction of an implication. Exactly means an exact count. One supporting case proves possibility; one valid counterexample defeats necessity. Test uniqueness before choosing a single candidate.

2-Minute Revision

Classify the question before solving it. Conditional statements, truth counts and arrangements need different records, but each uses the same standard: an allowed case must satisfy the stated premises. Avoid reversing an implication or treating the first successful assignment as unique. Enumerate small candidate sets systematically, and state the surviving set when the clues leave more than one answer.

5-Minute Revision

For the key puzzle, assume A, B and C hold the key in turn. Record the truth values of “B holds it”, “B does not hold it” and “A does not hold it”. The vectors are false/true/false, true/false/true and false/true/true. Identify which satisfy exactly two truths. Then alter the required count to exactly one and solve again. This isolates the effect of one changed premise without inventing another clue.

Vyyuha Quick Recall

Premises, cases, claim: preserve the rules, test valid cases, and match the strength of the conclusion to the evidence.