What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? forall y_4: R(y_4) -> U_2(y_4). forall y_4: R(y_4) -> R_3(y_4). exists y_4: U_2(y_4) <-> R(y_4). forall y_4: ~R_3(y_4).
forall y_4: ~R(y_4). exists y_4: U_2(y_4) -> R(y_4). exists y_4: R(y_4) -> U_2(y_4).