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_1: P_4(x_1) or S(x_1). forall x_1: ~Q_1(x_1). exists x_1: P_4(x_1) -> Q_1(x_1).
exists x_1: ~P_4(x_1) can be inferred via the existential modus tollens rule.