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: ~R_4(z). exists z: R_4(z) <-> R(z).
exists z: R_4(z) -> R(z) can be inferred via the existential biconditional elimination rule. exists z: R(z) -> R_4(z) can be inferred via the existential biconditional elimination rule. exists z: ~R(z) can be inferred via the existential biconditional elimination rule.