What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? r_4 -> p_11. p_11 -> r_4. u_3 -> r_4. p_11 -> u_3.
r_4 -> u_3. u_3 -> p_11. p_11 -> r_4. r_4 <-> p_11. p_11 <-> r_4.