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 y_2: U_1(y_2) -> P_4(y_2). forall y_2: P_4(y_2) -> U_1(y_2). forall z: P_4(z).
forall y_2: U_1(y_2) <-> P_4(y_2) can be inferred via the universal biconditional introduction rule. forall y_2: P_4(y_2) <-> U_1(y_2) can be inferred via the universal biconditional introduction rule.