What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? q_2 <-> R_23(a_23). u <-> q_7. forall x_23: ~R_23(x_23). ~u.
q_2 -> R_23(a_23). u -> q_7. R_23(a_23) -> q_2. q_7 -> u. ~q_7.