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: P_2(z) -> U(z). ~P_2(a_5). forall z: U(z) -> P_2(z).
forall z: P_2(z) <-> U(z) can be inferred via the universal biconditional introduction rule. forall z: U(z) <-> P_2(z) can be inferred via the universal biconditional introduction rule.