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: W(x) -> ~U(x). forall x: ~S_1(x). forall x: S_1(x) or U(x).
forall x: U(x) can be inferred via the universal disjunctive syllogism rule.