There looks to be an error in the first worked tutorial example - see below Given 1. (p⊃q)·(q⊃~p) 2. p∨q 3. ~q / s·t The proof as given in the tutorial 1. (p⊃q)·(q⊃~p) 2. p∨q ⇒ (q∨~p) ... (4) 4. (q∨~p) 3. ~q ⇒ ~p ... (5) 5. ~p 2. p∨q ⇒ q ... (6) ⇒ q ∨ (s·t) ... (7) 3. ~q 7. q∨(s·t) ⇒ s.t =========================== Now, from (3) and (6) above we have 3. ~q is true 6. q is true ⇒ ~q = q How can this be possible?
Thanks! I'll go back and double check when I get a chance. It's entirely possible that there's a mistake. Super busy with the end of the semester, but I'll definitely get to it.
