Translate the following inference to logic notation: For all x, if x_13 were a sailor, then x_13 is an electrician. For all x, if x_13 were a lawyer, then x_13 is a sailor. For all x, if x_13 were a writer, then x_13 is a lawyer. There is at least one x for which x_13 is an electrician if and only if x_13 is a writer. Therefore there is at least one x for which x_13 is a sailor if and only if x_13 is a writer.
forall x: P(x) -> Q(x). forall x: R(x) -> P(x). forall x: S(x) -> R(x). exists x: Q(x) <-> S(x). Therefore exists x: P(x) <-> S(x).