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: exists z: ~R(z). forall z: S_4(z) <-> R(z). forall z: R(z) -> S_4(z).
forall z: S_4(z) -> R(z) can be inferred via the universal biconditional elimination rule. forall z: R(z) -> S_4(z) can be inferred via the universal biconditional elimination rule. exists z: ~S_4(z) can be inferred via the existential biconditional elimination rule.