Consider the following premises. forall z_1: ~W(z_1). w_3 -> W(b_1). W(b_1) -> w_3. Can we infer w_3 from them?
 From forall z_1: ~W(z_1) we can infer ~W(b_1). From w_3 -> W(b_1), W(b_1) -> w_3 we can infer w_3 <-> W(b_1). From w_3 <-> W(b_1) we can infer w_3 -> W(b_1). Finally, from w_3 -> W(b_1), ~W(b_1) we can infer ~w_3, which contradicts w_3. Therefore, the answer is no.