What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? s_3 <-> p_18. s_3 or ~q_18. p_18 <-> q_18.
q_18 -> s_3. s_3 -> p_18. p_18 -> q_18. p_18 -> s_3. q_18 -> p_18.