Translate the following inference to logic notation: For all x, if x_11 plays squash, then x_11 is sleeping. Richard is not sleeping. For all x, x_11 will sleep if and only if x_11 will play squash. Therefore Richard is not playing squash.
forall x: P(x) -> Q(x). ~Q(a). forall x: Q(x) <-> P(x). Therefore ~P(a).