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(x_9). Q_9(a_5).
exists x: Q_9(x) can be inferred via the existential generalization rule. forall x_9: P_9(x_9) -> Q_9(x_9) can be inferred via the universal biconditional elimination rule. forall x_9: Q_9(x_9) -> P_9(x_9) can be inferred via the universal biconditional elimination rule.