Consider the following premises. forall z: R(z) -> W(z). forall z: W(z) -> T(z). forall z: T(z) -> W(z). forall z: T(z) -> R(z). Can we infer forall z: T(z) <-> W(z) from them? If possible, name the inference rules being used at each step.
We can infer forall z: T(z) <-> W(z) via the universal biconditional introduction rule. Therefore, the answer is yes.