Translate the following inference to logic notation: There is at least one x for which x_8 is a police officer if and only if x_8 is an artist. For all x, x_8 is a police officer or x_8 is not an artist. Therefore there is at least one x for which x_8 is an artist if and only if x_8 is a police officer.
exists x: P(x) <-> Q(x). forall x: P(x) or ~Q(x). Therefore exists x: Q(x) <-> P(x).