Math

Five ways to prove P=>Q

  1. P => Q (direct proof)
  2. -Q =>-P (proof by contrapositive)
  3. (P ^ -Q) => Q (proof by contradicting the conclusion)
  4. (P ^ -Q) => -P (proof by contradicting the hypothesis)
  5. (P ^ -Q) => (R ^ -R) (proof by reductio ad absurdum)