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