Translate the following inference to logic notation: For all x, if z were a sailor, then z is drinking water. If Thomas reads a book, then Karen is a sailor. If Karen drinks water, then Thomas is reading a book. Therefore Karen is drinking water if and only if Karen is a sailor.
forall x: P(x) -> Q(x). p -> P(a). Q(a) -> p. Therefore Q(a) <-> P(a).