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_9: P_9(x_9). Q_9(a_8) -> w_2. w_2 <-> P_9(a_8).
w_2 -> P_9(a_8) can be inferred via the biconditional elimination rule. P_9(a_8) -> w_2 can be inferred via the biconditional elimination rule.