Translate the following inference to logic notation: For all x, if x_13 were a taxi driver, then x_13 is sad. For all x, x_13 is not sad. There is at least one x for which if x_13 were a lawyer, then x_13 is playing a game. For all x, x_13 will play a game if and only if x_13 is a lawyer. For all x, x_13 is a lawyer if and only if x_13 is a taxi driver. Therefore there is at least one x for which x_13 will not play a game.
forall x: P(x) -> Q(x). forall x: ~Q(x). exists x: R(x) -> S(x). forall x: S(x) <-> R(x). forall x: R(x) <-> P(x). Therefore exists x: ~S(x).