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_13: U(x_13) -> U_4(x_13). forall x_13: R_1(x_13) -> U(x_13). forall x_13: U_4(x_13) -> Q_13(x_13). forall x_13: Q_13(x_13) -> R_1(x_13). forall x_13: ~R_1(x_13).
forall x_13: ~Q_13(x_13) can be inferred via the universal modus tollens rule. forall x_13: U_4(x_13) -> R_1(x_13) can be inferred via the universal transitivity rule. forall x_13: Q_13(x_13) -> U(x_13) can be inferred via the universal transitivity rule. exists x_13: U(x_13) -> Q_13(x_13) can be inferred via the existential transitivity rule. exists x_13: R_1(x_13) -> U_4(x_13) can be inferred via the existential transitivity rule.