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) or R(z). forall z: U_2(z) <-> R_4(z). forall z: P_3(z) -> U_2(z). forall z: R_4(z) -> P_3(z). exists z: R(z) -> U_2(z).
forall z: R_4(z) -> U_2(z) can be inferred via the universal transitivity rule. forall z: U_2(z) -> R_4(z) can be inferred via the universal biconditional elimination rule. forall z: R_4(z) -> U_2(z) can be inferred via the universal biconditional elimination rule.