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 x_4: Q(x_4) -> P_4(x_4). forall x_4: Q(x_4) or Q_4(x_4). forall x_4: P_4(x_4) <-> Q_4(x_4).
forall x_4: P_4(x_4) -> Q_4(x_4) can be inferred via the universal biconditional elimination rule. forall x_4: Q_4(x_4) -> P_4(x_4) can be inferred via the universal biconditional elimination rule.