Translate the following inference to logic notation: For all x, x_4 is a carpenter if and only if x_4 is an electrician. For all x, x_4 is not rich. For all x, x_4 is an electrician if and only if x_4 is rich. Therefore for all x, x_4 is not a carpenter.
forall x: P(x) <-> Q(x). forall x: ~R(x). forall x: Q(x) <-> R(x). Therefore forall x: ~P(x).