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: P_13(x_13) or Q_13(x_13). forall x_13: Q_13(x_13) -> S_2(x_13). U(a_5) or r_2. forall x_13: P_13(x_13) -> S_2(x_13). forall x_13: U(x_13) -> ~S_2(x_13).
forall x_13: S_2(x_13) can be inferred via the universal disjunction elimination rule.