1. J ⊃ (K ⊃ L) 2. J ⊃ (M ⊃ L) 3. ~L / J ⊃ ~(K v M) | 4. J Assumption for Conditional Proof | 5. K ⊃ L 1,4, Modus Ponens | 6. ~K 5,3, Modus Tollens | 7. M ⊃ L 2,4, Modus Ponens | 8. ~M 7,3, Modus Tollens | 9. ~K ● ~M 6,8, Conjunction |10. ~(K v M) 9, DeMorgan's Law 11. J ⊃ ~(K v M) Lines 4-10 Conditional Proof Edwin