Translate the following inference to logic notation: For all x, x_7 is a lawyer if and only if x_7 is an artist. For all x, x_7 is a lawyer or x_7 is not an artist. Therefore for all x, x_7 is a lawyer if and only if x_7 is an artist.
forall x: P(x) <-> Q(x). forall x: P(x) or ~Q(x). Therefore forall x: P(x) <-> Q(x).