Translate the following inference to logic notation: For all x, x_1 is not a taxi driver. There is at least one x for which if x_1 were a janitor, then x_1 is a taxi driver. For all x, x_1 will climb a mountain if and only if x_1 is a janitor. Therefore there is at least one x for which x_1 will not climb a mountain.
forall x: ~P(x). exists x: Q(x) -> P(x). forall x: R(x) <-> Q(x). Therefore exists x: ~R(x).