@@mxlexrd yes I did. That’s what comes of trying to do the negation in your head. Anyway, it makes sense because P and not Q represents a counter example.
Let's say P is false and Q is false. So, ~Q-->~P is true, which means P-->Q is also true. But, Q is false, so P-->~Q is true. So, P-->Q and P-->~Q, but we don't have any contradiction.
