What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: forall z: W_4(z). exists z: S(z) <-> W_4(z). forall z: S(z) -> T(z).
exists z: S(z) -> W_4(z) can be inferred via the existential biconditional elimination rule. exists z: W_4(z) -> S(z) can be inferred via the existential biconditional elimination rule.