Consider the following premises. exists x_18: P_12(x_18). forall x_18: W(x_18) <-> Q_18(x_18). forall x_18: P_12(x_18) -> W(x_18). forall x_18: S(x_18). Can we infer forall x_18: ~S(x_18) from them? If possible, name the inference rules being used at each step.
That contradicts the premises. Therefore the answer is no.