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_18: P_14(x_18) or Q_14(x_18). forall x_18: S_1(x_18) <-> Q_18(x_18). forall x_18: ~R_14(x_18) or R_2(x_18). exists x_18: Q_14(x_18) -> R_14(x_18). forall x_18: R_2(x_18) -> Q_18(x_18). forall x_18: P_14(x_18) -> R_14(x_18).
exists x_18: R_14(x_18) can be inferred via the existential disjunction elimination rule. forall x_18: S_1(x_18) -> Q_18(x_18) can be inferred via the universal biconditional elimination rule. forall x_18: Q_18(x_18) -> S_1(x_18) can be inferred via the universal biconditional elimination rule.