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_20: ~P_11(x_20). forall x_20: P_20(x_20) or ~U_2(x_20). exists x_20: P_20(x_20) -> P(x_20). forall x_20: P_11(x_20) or U_2(x_20).
forall x_20: U_2(x_20) can be inferred via the universal disjunctive syllogism rule. forall x_20: U_2(x_20) -> P_20(x_20) can be inferred via the universal rewriting rule.