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: Q_4(z) -> R(z). forall z: R(z) -> Q_4(z). exists z: U_2(z) or ~Q_4(z).
exists z: Q_4(z) -> U_2(z) can be inferred via the existential rewriting rule. forall z: Q_4(z) <-> R(z) can be inferred via the universal biconditional introduction rule. forall z: R(z) <-> Q_4(z) can be inferred via the universal biconditional introduction rule.