Consider the following premises. forall y: U_4(y) or ~W(y). forall y: U_4(y) <-> W(y). Can we infer forall y: W(y) -> U_4(y) from them? If possible, name the inference rules being used at each step.
 From forall y: U_4(y) <-> W(y) we can infer forall y: U_4(y) -> W(y) via universal biconditional elimination. Finally, from forall y: U_4(y) or ~W(y) we can infer forall y: W(y) -> U_4(y) via universal rewriting. Therefore, the answer is yes.