Translate the following inference to logic notation: For all x, x_11 will drink water if and only if x_11 is sad. For all x, x_11 is sad if and only if x_11 will drink water. Therefore if Jessica drinks water, then Jessica is sad.
forall x: P(x) <-> Q(x). forall x: Q(x) <-> P(x). Therefore P(a) -> Q(a).