Consider the following premises. p -> W(a_20). ~S_20(a_20). forall x_20: W(x_20) <-> S_20(x_20). Can we infer p from them?
 From forall x_20: W(x_20) <-> S_20(x_20) we can infer W(a_20) <-> S_20(a_20). From W(a_20) <-> S_20(a_20), ~S_20(a_20) we can infer ~W(a_20). Finally, from p -> W(a_20), ~W(a_20) we can infer ~p, which contradicts p. Therefore, the answer is no.