Translate the following inference to logic notation: For all x, x_6 is a writer. For all x, if x_6 were a writer, then x_6 is a police officer. There is at least one x for which x_6 is a sailor if and only if x_6 is a police officer. Therefore there is at least one x for which x_6 is a sailor.
forall x: P(x). forall x: P(x) -> Q(x). exists x: R(x) <-> Q(x). Therefore exists x: R(x).