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_2(x_9) or W(x_9). forall x_9: ~Q_9(x_9). exists x_9: P_4(x_9) <-> Q_9(x_9). forall x_9: P_2(x_9) or P_4(x_9).
forall x_9: P_4(x_9) or W(x_9) can be inferred via the universal resolution rule. exists x_9: P_4(x_9) -> Q_9(x_9) can be inferred via the existential biconditional elimination rule. exists x_9: Q_9(x_9) -> P_4(x_9) can be inferred via the existential biconditional elimination rule. exists x_9: ~P_4(x_9) can be inferred via the existential biconditional elimination rule.