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_15: T_1(x_15) -> P_4(x_15). forall x_15: P_15(x_15) or Q_15(x_15). forall x_15: Q_15(x_15) -> R_15(x_15). exists x_15: P_15(x_15) -> R_15(x_15). forall x_15: P_4(x_15) -> ~R_15(x_15).
exists x_15: R_15(x_15) can be inferred via the existential disjunction elimination rule.