At a glance
7
Occurrences
questions
6
Years
6
Papers
7
Worked
100%
When this method shows up
Years in which at least one question on this paper triggers the method.
Other top methods in Logic & Proof
- To disprove a 'for all' claim, build a single counterexample that obeys the hypothesis but breaks the conclusion×7
- Treat 'necessary' and 'sufficient' as two separate one-way tests, and break whichever direction can fail×7
- For a 'which of I, II, III must be true' item, confirm the forced ones then kill each survivor with one targeted counterexample×6
- Settle a polynomial's real-root count from its shape, not by solving×6
- Mind the direction of an implication: the contrapositive keeps the truth value, the converse and inverse do not×6
See the worked examples
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