Translate the following inference to logic notation: For all x, x_8 is an artist if and only if x_8 is a doctor. For all x, x_8 is a taxi driver if and only if x_8 is an artist. For all x, x_8 is not a taxi driver. Therefore for all x, x_8 is not a doctor.
forall x: P(x) <-> Q(x). forall x: R(x) <-> P(x). forall x: ~R(x). Therefore forall x: ~Q(x).