Translate the following inference to logic notation: For all x, if y were an electrician, then y is sad. For all x, y is sad if and only if y is an electrician. Therefore for all x, y is an electrician if and only if y is sad.
forall x: P(x) -> Q(x). forall x: Q(x) <-> P(x). Therefore forall x: P(x) <-> Q(x).