Consider the following premises. forall z: W(z) or ~R_4(z). forall z: R_4(z) <-> W(z). Can we infer forall z: W(z) -> R_4(z) from them? If possible, name the inference rules being used at each step.
 From forall z: W(z) or ~R_4(z) we can infer forall z: R_4(z) -> W(z) via universal rewriting. Finally, from forall z: R_4(z) <-> W(z) we can infer forall z: W(z) -> R_4(z) via universal biconditional elimination. Therefore, the answer is yes.