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: exists x_4: Q_4(x_4). forall x_4: P_4(x_4) -> ~Q_4(x_4). forall x_4: S(x_4) -> P_4(x_4).
exists x_4: ~P_4(x_4) can be inferred via the existential modus tollens rule.