Translate the following inference to logic notation: There is at least one x for which x_4 is not a police officer. For all x, x_4 is a police officer if and only if x_4 will climb a mountain. Therefore there is at least one x for which x_4 will not climb a mountain.
exists x: ~P(x). forall x: P(x) <-> Q(x). Therefore exists x: ~Q(x).