Translate the following inference to logic notation: For all x, if z were a politician, then z is playing squash. For all x, z is a politician if and only if z will play squash. Therefore for all x, if z plays squash, then z is a politician.
forall x: P(x) -> Q(x). forall x: P(x) <-> Q(x). Therefore forall x: Q(x) -> P(x).