Let p be the proposition “pigs can fly,” c be the proposition“cows can whistle,” and s be the proposition “the sun rises in thewest.” (Should not consider whether these propositions are truewhen solving the problem.)
(a) Give a formal proof that (p ∧ c) ↔ (p ∧ s) follows from p →(c ↔ s).
(b) [ Use a truth table to show that (p ∧ c) ↔ (p ∧ s) ≡ p → (c↔ s).
(c) What else would we need to do, beyond what the work of part(a), in order to establish the equivalence of part (b) using aformal proof rather than
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