Solutions

  1. Answer: Let s = I will study, t  = I will learn. The argument is: ((s → t) ∧ (¬t)) → (¬s) , call the argument a.



    Since a is a tautology, the argument is valid.

  2. Answer: In any true statement S, replace; ∧ with ∨, ∨ with ∧, 0 with 1, 1 with 0, ⇐ with ⇒,  and ⇒ with ⇐.  Leave all other connectives unchanged.