What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? q_8 -> r_8. w_4 <-> r_8. r_8 -> u. ~w_4. u -> q_8.
q_8 -> u. r_8 -> q_8. u -> r_8. w_4 -> r_8. r_8 -> w_4. ~r_8.