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Construct derivations that establish a. {A B, C A, D B} C D b. '[A (B C)] [(A amp; B) C]' is a theorem in SD c.
2. Construct derivations that establish
a. {∼A ∨∼B, ∼C ⊃A, ∼D ⊃B} ├C ∨D
b. ‘[A ⊃(B ⊃C)] ⊃[(A & B) ⊃C]’ is a theorem in SD
c. {A ≡B, ∼(A ∨∼B} is inconsistent in SD