The restriction only says not to use "implication". It does NOT say not to use "MATERIAL implication". 1. B > (A > C) 2. (B > C) > F /A > F 3. B > (~A v C) 1, Material implication 4. ~B v (~A v C) 3, Material implication 5. ~B v (C v ~A) 4, Commutation 6. (~B v C) v ~A 5, Association 7. (B > C) v ~A 6, Material implication 8. ~A v (B > C) 7, Commutation 9. A > (B > C) 8, Material implication 10. A > F 9,2, Hypothetical syllogism Edwin