logic pset3

Final version released: Feb 9

You may use any of the rules of inference, including reductio ad absurdum, to prove the following sequents.

1. (P∧Q) → ¬Q ⊢ P → ¬Q

2. ¬(P→Q) ⊢ P

3. ¬(P→Q) ⊢ Q → R

4. P → Q ⊢ ¬P ∨ Q

5. (P∧¬P) ∨ Q ⊢ Q

6. P → (Q∨R) ⊢ ¬R → (P→Q)