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_13: S_4(x_13) -> P(x_13). forall x_13: ~P_13(x_13). exists x_13: P_13(x_13) or S_4(x_13).
exists x_13: S_4(x_13) can be inferred via the existential disjunctive syllogism rule.