Translate the following inference to logic notation: For all x, if x_12 drinks water, then x_12 is an electrician. If Richard were an electrician, then Richard is drinking water. If Richard drinks water, then Richard is an electrician. Therefore Richard is an electrician if and only if Richard is drinking water.
forall x: P(x) -> Q(x). Q(a) -> P(a). P(a) -> Q(a). Therefore Q(a) <-> P(a).