Translate the following inference to logic notation: For all x, if x_4 were a server, then x_4 is playing squash. There is at least one x for which x_4 will play squash if and only if x_4 is a server. For all x, x_4 will not play squash. Therefore there is at least one x for which x_4 is not a server.
forall x: P(x) -> Q(x). exists x: Q(x) <-> P(x). forall x: ~Q(x). Therefore exists x: ~P(x).