Translate the following inference to logic notation: For all x, if x_13 were excited, then x_13 is playing squash. For all x, x_13 will play squash if and only if x_13 will sleep. There is at least one x for which x_13 will not sleep. For all x, if x_13 plays squash, then x_13 is excited. Therefore there is at least one x for which x_13 is not excited.
forall x: P(x) -> Q(x). forall x: Q(x) <-> R(x). exists x: ~R(x). forall x: Q(x) -> P(x). Therefore exists x: ~P(x).