1. (UvD)vK 2. ~D&(~KvM) 3. (KvU)>~M /~(DvM) 4. Uv(DvK) 1, Association 5. Uv(KvD) 4, Commutation 6. (UvK)vD 5, Association 7. (KvU)vD 6, Commutation 8. Dv(KvU) 7, Commutation 9. ~D 2, Simplification 10. KvU 8,9, Disjunctive syllogism 11. ~M 3,10, Modus ponens 12. ~D&~M 9,11, Conjunction 13. ~(DvM) 12, DeMorgan Edwin