Translate the following inference to logic notation: There is at least one x for which x_6 is a sailor if and only if x_6 is sad. For all x, if x_6 were an electrician, then x_6 is not a bartender. For all x, x_6 is sad if and only if x_6 is an electrician. For all x, x_6 is a bartender. Therefore there is at least one x for which x_6 is not a sailor.
exists x: P(x) <-> Q(x). forall x: R(x) -> ~S(x). forall x: Q(x) <-> R(x). forall x: S(x). Therefore exists x: ~P(x).