What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? q_4 <-> q_15. ~q_15. S_11(a_11) -> q_4. ~R_11(a_11) or u. forall x_11: R_11(x_11) or S_11(x_11).
q_4 -> q_15. q_15 -> q_4. ~q_4.