1. C → ( D → H) 2. D ∙ ~H 3. H v T ∴ ~C ∙ T ------------------- 4. ~~D ∙ ~H 2 Double Negation 5. ~(~D v H) 4 De Morgan's Law 6. ~(D → H) 5 Material Implication 7. ~C 1,6 Modus Tollens 8. ~H ∙ D 2 Commutation 9. ~H 8 Simplification 10. T 3,9 Disjunctive Syllogism 11. ~C ∙ T 7,10 Conjunction