Translate the following inference to logic notation: For all x, x_13 is an electrician or x_13 will make tea. For all x, if x_13 were an electrician, then y_1 is curious. For all x, if y_1 were curious, then y_1 is playing tennis. For all x, x_13 will make tea if and only if y_1 is curious. Therefore Robert is playing tennis.
forall x: P(x) or Q(x). forall x: P(x) -> R(x). forall x: R(x) -> S(x). forall x: Q(x) <-> R(x). Therefore S(a).