1. D 2. ~C 3. (A v B) -> C 4. [(~A • D) • ~B] -> (P -> Q) :. ~P v Q ------------------------------------------------------- 6. ~(A v B) 3,2 Modus Tollens 7. ~A • ~B 6 De Morgan's Law 8. (~A • ~B) • D 7,1 Conjunction 9. ~A • (~B • D) 8 Association 10. ~A • (D • ~B) 9 Commutation 11. (~A • D) • ~B 10 Association 12. P -> Q 4,11 Modus Ponens 13. ~P v Q 12 Material Implication