Translate the following inference to logic notation: Mary is a politician if and only if Susan is an electrician. For all x, z is not an electrician. For all x, x_7 will cook if and only if x_7 is a politician. Therefore Mary is not cooking.
P(a) <-> Q(b). forall x: ~Q(x). forall x: R(x) <-> P(x). Therefore ~R(a).