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: R(a_2) -> U(a_2). forall y_4: R(y_4) or ~U(y_4). ~R(a_2).
forall y_4: U(y_4) -> R(y_4) can be inferred via the universal rewriting rule.